(19)
(11)EP 3 212 601 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
04.12.2019 Bulletin 2019/49

(21)Application number: 15794108.9

(22)Date of filing:  30.10.2015
(51)International Patent Classification (IPC): 
C07C 29/145(2006.01)
C07C 41/26(2006.01)
C07C 209/68(2006.01)
C07C 1/24(2006.01)
C10G 3/00(2006.01)
C07C 43/23(2006.01)
C07C 15/073(2006.01)
C07C 41/18(2006.01)
C07C 209/32(2006.01)
C07C 45/30(2006.01)
C07C 45/51(2006.01)
C07C 211/45(2006.01)
C07C 15/06(2006.01)
C07C 43/205(2006.01)
(86)International application number:
PCT/EP2015/075333
(87)International publication number:
WO 2016/066835 (06.05.2016 Gazette  2016/18)

(54)

A MILD CATALYTIC REDUCTION OF C-O BONDS AND C=O BONDS USING A RECYCLABLE CATALYST SYSTEM

MILDE KATALYTISCHE REDUKTION VON C-O- UND C=O-BINDUNGEN MITHILFE EINES RECYCLINGFÄHIGEN KATALYSATORSYSTEMS

RÉDUCTION CATALYTIQUE MODÉRÉE DE LIAISONS C-O ET LIAISONS C=O À L'AIDE D'UN SYSTÈME CATALYSEUR RECYCLABLE


(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

(30)Priority: 30.10.2014 US 201462072774 P

(43)Date of publication of application:
06.09.2017 Bulletin 2017/36

(73)Proprietor: Organofuel Sweden AB
852 30 Sundsvall (SE)

(72)Inventors:
  • CÓRDOVA, Armando
    113 46 Stockholm (SE)
  • AFEWERKI, Samson
    756 49 Uppsala (SE)
  • PALO-NIETO, Carlos
    Bristol, Bristol BS8 2QA (GB)

(74)Representative: Swea IP Law AB 
P.O. Box 44
151 21 Södertälje
151 21 Södertälje (SE)


(56)References cited: : 
US-A- 4 421 938
  
  • FENG J ET AL: "Catalytic transfer hydrogenolysis of alpha-methylbenzyl alcohol using palladium catalysts and formic acid", APPLIED CATALYSIS A: GENERAL, ELSEVIER SCIENCE, AMSTERDAM, NL, vol. 354, no. 1-2, 15 February 2009 (2009-02-15), pages 38-43, XP025879686, ISSN: 0926-860X, DOI: 10.1016/J.APCATA.2008.11.008 [retrieved on 2008-11-21]
  • OKAMOTO M ET AL: "Polymers as novel modifiers for supported metal catalyst in hydrogenation of benzaldehydes", JOURNAL OF CATALYSIS, ACADEMIC PRESS, DULUTH, MN, US, vol. 276, no. 2, 15 December 2010 (2010-12-15), pages 423-428, XP027493850, ISSN: 0021-9517, DOI: 10.1016/J.JCAT.2010.10.008 [retrieved on 2010-11-13]
  • L. B. BELYKH ET AL: "Hydrogenation catalysts based on palladium bisacetylacetonate and lithium tetrahydroaluminate: Formation mechanism and reasons for modified effect of water", RUSSIAN JOURNAL OF APPLIED CHEMISTRY., vol. 81, no. 6, 1 June 2008 (2008-06-01), pages 956-964, XP055244945, US ISSN: 1070-4272, DOI: 10.1134/S1070427208060062
  • CHO RIM LEE ET AL: "Catalytic roles of metals and supports on hydrodeoxygenation of lignin monomer guaiacol", CATALYSIS COMMUNICATIONS, ELSEVIER SCIENCE, AMSTERDAM, NL, vol. 17, 11 October 2011 (2011-10-11), pages 54-58, XP028393973, ISSN: 1566-7367, DOI: 10.1016/J.CATCOM.2011.10.011 [retrieved on 2011-10-17]
  • SHELDON G SHORE, DING ERRUN, PARK COLIN, KEANE MARK A: "Vapor phase hydrogenation of phenol over silica supported Pd and PdAYb catalysts", CATALYSIS COMMUNICATIONS, vol. 3, 1 February 2002 (2002-02-01), pages 77-84, XP055245365,
  • THAKAR ET AL: "Deuteration study to elucidate hydrogenolysis of benzylic alcohols over supported palladium catalysts", JOURNAL OF CATALYSIS, ACADEMIC PRESS, DULUTH, MN, US, vol. 246, no. 2, 15 February 2007 (2007-02-15), pages 344-350, XP005887966, ISSN: 0021-9517, DOI: 10.1016/J.JCAT.2006.12.016
  • OSCAR VERHO ET AL: "Mild and Selective Hydrogenation of Nitro Compounds using Palladium Nanoparticles Supported on Amino-Functionalized Mesocellular Foam", CHEMCATCHEM, vol. 6, no. 11, 18 September 2014 (2014-09-18), pages 3153-3159, XP055245388, DE ISSN: 1867-3880, DOI: 10.1002/cctc.201402488
  
Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


Description

FIELD OF INVENTION



[0001] The present invention relates to eco-friendly methodology for the conversion of alcohols to hydrocarbons as well as conversion of carbonyls such as aldehydes and ketones to alcohols and then hydrocarbons

BACKGROUND



[0002] Alcohols are versatile organic compounds reagents and can be used as precursors for other classes of organic molecules in synthetic chemistry. Catalytic hydrogenolysis of C-OH bonds is a very important synthetic technique; it is widely used in organic synthesis [1-3], pharmaceutical production [4,5] and biomass conversion [6-8]. Reduction of alcohols to the corresponding hydrocarbon is usually accomplished sequence of steps. Conventionally, hydrogenolysis of C-OH bond is achieved with molecular hydrogen using noble metals as catalysts. In some cases, stoichiometric reducing agents such as metal hydrides are used. Nevertheless, these traditional hydrogenolysis methods have some drawbacks. One drawback is the use of molecular hydrogen or stoichiometric reducing agents that often causes safety and environmental problems, because molecular hydrogen and metal hydrides are flammable, explosive and hazardous. Another drawback is the use of high temperature and high-pressure that will necessitate expensive high-pressure equipment, thereby increasing the cost of the process and resulting in many troubles in manipulation. An additional drawback is its low selectivity due to the hash reaction conditions employed. In contrast to the traditional hydrogenolysis methods, catalytic transfer hydrogenolysis (CTH) uses hydrogen donors to provide hydrogen species in situ; hence it offers the possibility to overcome the drawbacks of the traditional hydrogenolysis methods.

[0003] CTH is an important synthetic technique in organic chemistry. As neither hydrogen containment nor a pressure vessel is required; the mild reaction conditions offer considerable advantages over the conventional method of catalytic hydrogenolysis. For the transfer hydrogenolysis or hydrogenation, it is necessary to select an efficient catalyst and suitable hydrogen donors. Recently, formic acid has been employed as the source of hydrogen and has many advantages in regards to handling, transport, and storage and can easily be generated form hydrogen gas and carbon dioxide.

[0004] Generally, metal (VIII group elements) such as palladium ruthenium and Raney nickel are employed as the catalysts for the transfer hydrogenolysis. Palladium is arguably one of the most powerful and versatile transition-metal catalysts which can be immobilized on various heterogeneous supports and be used for a variety of organic transformations. Palladium heterogeneous catalyst can be recycled by simple filtration and reused in several cycles without the loss of efficiency with the consequently advantages such as economic and environmental. Recently, we developed asymmetric carbocyclizations implementing a heterogeneous palladium catalyst with a simple chiral amine co-catalyst. However, it is not sure whether the Palladium heterogeneous catalyst could be reused for the CTH of alcohols.

[0005] Feng Et Al., Catalytic transfer hydrogenolysis of alpha-methylbenzyl alcohol using palladium catalysts ans formic acid, Applied Catalysis A: General, Elsevier Science, Amsterdam, NL, Vol 354, No 1-2, February 2009, pages 38-43, discloses the reduction of the C-OH bond to C-H in alpha-methylbenzyl alcohol using palladium catalysts and formic acid.

[0006] Okamoto Et Al., Polymers as novel modifiers for supported metal catalyst in hydrogenation of benzalhydes., J of Catalysis, Academic Press, Duluth, MN, US, vol 276, No 2, 15 Dec 2010, pages 423-428, discloses hydrogenation of benzaldehydes to toluene using Pd/SiO2 as catalyst.

[0007] Belykh L., Et Al, Hydrogenation catalysts based on palladium biacetylacetonate and lithium tetrahydroaluminate:Formation mechanism and reasons for modified effect of water., Russian J of Applied Chemistry, vol 81, no 6, June 2008, pages 956-964, discloses hydrogenation catalysts based on palladium bisacetylacetonate and lithium tetrahydroaluminate for the reduction of benzaldehydes to toluene.

[0008] Cho Rim Lee, Et Al., Catalytic roles of metals and supports on hydrodeoxygenation of lignin monomer guaiacol, Catalysis communications, Elsevier Science, Amsterdam, NL, Vol 17, 11 October 2011, pages 54-58, discloses hydrodeoxygenation of lignin monomer guaiacol to cyclohexane using Pd/SiO2Al2O3 for use in fuels.

[0009] Sheldon G Shore, Et Al, Vapor phase hydrogenation of phenol over silica supported Pd and PdAYb catalysts, Catalysis Communication, 1 February 2002, pages 77-84, discloses hydrogenation of phenol to cyclohexanone and cyclohexanol using H2 as a hydrogen donor.

[0010] US4 421 938, discloses the convertion of alcohol to aldehydes by treating the alcohols with an oxygen-containing gas in the presence of a catalyst comprising at least two oxides of metals selected from molybdenum, tungsten, cobalt, nickel, manganese, iron and chromium.

[0011] Thakar Et Al., Deuteration study to elucidate hydrogenolysis of benzylic alcohols over supported palladium catalysts, J of Catalysis, Academic Press, Suluth, MN, US, vol 246, no 2, 15 February 2007, pages 344-350, discloses hydrogenolysis of 4-isobutylacetophenone over palladium catalysts supported on SiO2.

[0012] Verho O., Et Al., Mild and selective hydrogenation of nitro compounds using palladium nanoparticles supported on amino-functionalized mesocellular foam. Chemcatchem, vol 6, no 11, 18 September 2014, pages 3153-3159, discloses reduction of nitro groups to amino groups using Pd(0)-AmP-MCF as a catalyst and H2 gas as a hydrogen donor.

OBJECT OF THE INVENTION



[0013] It is an objective of the invention to synthesize hydrocarbons from alcohols using a heterogeneous metal catalyst system.

[0014] Another objective of the invention is to depolymerize lignin followed by the above conversion of carbonyls or alcohols to hydrocarbons, respectively.

[0015] Another objective of the invention is to link it to selective catalytic oxidations of arylpolydiols such as lignin followed depolymerization and then conversion of carbonyls or alcohols to hydrocarbons, respectively.

[0016] A still further objective of the invention is to provide a method of the aforementioned kind that is advantageous from an environmental and health standpoint.

[0017] Even more objectives will become evident from a study of the summary of the invention, a number of preferred embodiments illustrated in a drawing, and the appended claims.

SUMMARY OF THE INVENTION



[0018] Described herein is the use of a heterogeneous metal catalyst that can convert alcohols to hydrocarbons using a suitable reducing agent (Scheme 1).



[0019] Described herein is the use of a heterogeneous metal catalyst that can convert an ether bond beta to a hydroxyl group or alpha to a carbonyl group to hydrocarbons, respectively, using suitable reducing agents.

[0020] Described herein is the use of a heterogeneous metal catalyst that can convert aldehydes or



[0021] An aspect of the invention is the catalytic selective oxidation of primary or secondary alcohols of "lignin-type" structure to the corresponding carbonyl, respectively. Followed by one-pot depolymerization and then reduction by a heterogeneous metal catalyst to the corresponding hydrocarbon using a suitable reducing agent (Scheme 3).



[0022] Another aspect is the synthesis of hydrocarbons and similar compounds starting from lignin and its derivatives using a combination of selective oxidations followed by depolymerization.

[0023] The method described herein is composed of key steps in which lignin is converted under environmentally benign conditions.

[0024] The method comprises the steps of:
  1. i. Providing an alcohol
  2. ii. Chemically converting the said alcohol to a carbonyl by a suitable modification method, i.e. oxidation
  3. iii. Convert the carbonyl to another carbonyl compound using a suitable depolymerization system
  4. iv. Conversion of the carbonyl to the corresponding alcohol by using a suitable heterogeneous metal catalyst and reducing agent,
  5. v. Conversion of the said alcohol to the corresponding hydrocarbon by using a suitable heterogeneous metal catalyst and reducing agent.


[0025] The oxidations can be performed in water or organic solvents. Suitable catalysts, depending on the nature of the reactive molecule, may be a heterogeneous metal catalyst, homogeneous metal catalyst, a metal-free catalyst, or an enzyme. Suitable oxidants, depending on the nature of the reactive molecule, may be oxygen, air, hydrogen peroxide.

[0026] The oxidized oligomer or polymer with a lignin-type structure is directly depolymerized to a smaller size carbonyl compound by using basic, oxidative, radical or organocatalytic conditions.

[0027] The carbonyl groups from the previous step are reduced to the corresponding alcohol by the heterogeneous catalyst using a suitable reducing agent. Suitable reducing agents, depending on the nature of the reactive molecule, may be hydrogen, formic acid, ammonium formiate.

[0028] The alcohol groups from the previous step are reduced to the corresponding hydrocarbons by the heterogeneous catalyst using a suitable reducing agent. Suitable reducing agents, depending on the nature of the reactive molecule, may be hydrogen, formic acid, ammonium formiate.

[0029] The method comprises the steps of:

ii. Providing an aldehyde or ketone

iii. Convert the carbonyl to another carbonyl compound using a suitable depolymerization system.

iv. Conversion of the carbonyl from step iii to the corresponding alcohol by using a suitable heterogeneous metal catalyst and reducing agent

v. Conversion of the said alcohol to the corresponding hydrocarbon by using a suitable heterogeneous metal catalyst and reducing agent.



[0030] The carbonyl groups are reduced to the corresponding alcohol by the heterogeneous catalyst using a suitable reducing agent. Suitable reducing agents, depending on the nature of the reactive molecule, may be hydrogen, formic acid, ammonium formiate.

[0031] The alcohol groups from the previous step are reduced to the corresponding alcohol by the heterogeneous catalyst using a suitable reducing agent. Suitable reducing agents, depending on the nature of the reactive molecule, may be hydrogen, formic acid, ammonium formiate.

[0032] Hence, in view of the above, the objects of the present invention is attained by a method of conversion of a C=O bond to a C-H bond, comprising the steps of:
  1. i. Providing an alcohol and converting the alcohol to a compound comprising a C=O bond, wherein the compound comprising a C=O is selected from an aldehyde and a ketone, wherein the conversion of the alcohol to a compound comprising a C=O bond comprises the step of:
    1. a. Oxidation with an oxidant and catalyst, wherein the oxidant is selected from H2O2, O2 and NaOCI, and wherein the catalyst is selected from heterogeneous supported metal catalyst, homogeneous organometallic complex,a metal-free catalyst (mediator), and enzyme (EC 1:10:3:2), and
  2. ii. Providing the compound comprising a C=O bond from the previous step, and
  3. iii. Reducing said compound comprising a C=O bond in a solvent comprising reducing agent and a catalyst, wherein the reducing agent is selected from ammonium formate, formic acid and H2 gas, and wherein the catalyst is selected from a heterogeneous metal catalyst, wherein the heterogeneous metal catalyst is a Pd(0)-nanocatalyst which is heterogeneously supported on silica containing material.


[0033] In the present invention, the catalyst is a Pd-catalyst selected from Pd(0)-amino functionalized silica support, preferably Pd(0)-AmP-silica support.

[0034] In a further preferred embodiment, the catalyst is a Pd-catalyst selected from Pd(0)-AmP-MCF and Pd(0)-AmP-CPG, preferably the Pd-catalyst is recyclable.

[0035] In a further preferred embodiment, the reducing agents are ammonium formiate and H2 gas, and wherein the solvent is preferably toluene.

[0036] Moreover, the reduction may be carried out at a temperature of 20-80 °C, preferably at ambient temperature or 80 °C.

[0037] In a further preferred embodiment, the alcohol is converted to an aldehyde in step i), wherein the conversion of the alcohol to an aldehyde is conducted in the presence of NaOCI, TEMPO (2,2,6,6-Tetramethylpiperidin-1-yl)oxyl), NaOH, KBr and O2, and wherein step i) may comprise the steps of:
  1. a. Adding a solution of KBr to a solution comprising the alcohol and TEMPO, preferably KBR is in a water solution and TEMPO is in CH2Cl2,
  2. b. Stirring the mixture, preferably at 0 °C,
  3. c. NaOCI solution is added to the reaction mixture, preferably the NaOCI solution has pH 9,
  4. d. Adding NaOH to the reaction mixture in the presence of O2, and
  5. e. Stirring the mixture, preferably at 0 °C, more preferably at 0 ° for 3 hours.


[0038] In a further preferred embodiment, the alcohol is converted to a ketone in step i), wherein the conversion of the alcohol to a ketone is conducted in the presence of O2, TEMPO, HNO3 and HCl, and wherein step i) may comprise the steps of:
  1. a. Adding TEMPO to the alcohol in the presence of O2,
  2. b. Adding a mixture of HNO3 in acetonitrile,
  3. c. Adding a mixture of HCI in acetonitrile, preferably also adding water and acetonitrile, and
  4. d. Optionally heating the mixture.


[0039] In a further preferred embodiment, the alcohol is a diol, and wherein said diol is in step i) converted to an aldol which then undergoes a spontaneous catalytic retro-aldol reaction to the corresponding aldehyde moieties, and wherein the C=O bond of the aldehydes are subsequently reduced to a C-H bond in step iii).

[0040] In a further preferred embodiment, the diol is selected from lignin and derivatives thereof, preferably the alcohol is lignin containing benzylic, allylic or aliphatic alcohols including β-O-4 aryl ether linkages, more preferably the lignin is selected from milled wood lignin, cellulolytic lignin, organosolv lignin and technical lignin from pulping processes, wherein the method may comprise the steps of:
  1. i. Providing lignin and oxidizing the lignin to a polymer comprising aldehyde groups,
  2. ii. The polymer comprising aldehyde groups which have been provided in the previous step subsequently undergo spontaneous catalytic retro-aldol reaction which leads to a depolymerization,
  3. iii. Reducing the aldehyde groups.


[0041] In a further preferred embodiment, the alcohol is a primary alcohol, and wherein the primary alcohol is converted to an aldehyde in step i), and wherein the C=O bond of the aldehyde is subsequently reduced to a C-H bond.

[0042] In a further preferred embodiment, the alcohol is selected from vanillyl alcohol, hydroxy-, methoxy- and ethoxybenzyl alcohols, and wherein vanillyl alcohol, hydroxy-, methoxy- and ethoxybenzyl alcohols are converted to their respective aldehydes in step i), and wherein the C=O bond of the aldehyde is subsequently reduced to a C-H bond.

[0043] In a further preferred embodiment, the alcohol is a secondary alcohol, and wherein said secondary alcohol is converted to a ketone in step i), and wherein the C=O bond of the ketone is subsequently reduced to a C-H bond.

[0044] In a further preferred embodiment, the object of the invention is attained by the products obtainable by the above preferred embodiments. Furthermore, the object of the invention is also attained by using said products as fuels.

[0045] Described herein is a method of conversion of a C-O or C=O bond to a C-H bond, comprising the steps of:
  1. i. Providing a compound comprising a C-O bond or a C=O bond, wherein said compound is selected from an aldehyde, a ketone, an alcohol, an aldol, a compound having an ether bond beta to a hydroxyl group, or a compound having an ether bond alpha to a carbonyl group, and
  2. ii. Reducing the C-O or C=O bond to a C-H bond in a solvent comprising reducing agent and a catalyst, wherein the reducing agent is selected from ammonium formate, formic acid and H2 gas, and wherein the catalyst is selected from heterogeneous metal catalyst and homogeneous organometallic complex, wherein the heterogeneous metal catalyst is a Pd(0)-nanocatalyst which is heterogeneously supported on silica containing material, wherein the homogeneous organometallic complex comprises Pd, Ir, Ru, Ni, Co, Cu complexes and
wherein an optional step of providing an alcohol and then converting the alcohol to a compound comprising a C=O bond is provided before step i).

[0046] The catalyst is a Pd-catalyst selected from Pd(0)-amino functionalized silica support, preferably Pd(0)-AmP-silica support.

[0047] The catalyst is a Pd-catalyst selected from Pd(0)-AmP-MCF and Pd(0)-AmP-CPG, preferably the Pd-catalyst is recyclable.

[0048] The reducing agent is selected from hydrogen, formic acid and ammonium formiate.

[0049] The reducing agent is ammonium formiate and formic acid when the compound comprising a C-O bond is an alcohol, and wherein the solvent may be ethanol and/or water, preferably a mixture of ethanol and water, more preferably the mixture of ethanol and water having a ratio of ethanol:water being 4:1. Moreover, ammonium formiate and formic acid may be added
  • in a ratio of 0.25 and 6.6, respectively, in relation to the alcohol, or
  • in a ratio of 0.25 and 3.3, respectively, in relation to the alcohol.


[0050] In a further preferred embodiment, the reducing agents are ammonium formiate and H2 gas when the compound comprising a C=O bond is an aldehyde, ketone, an aldol, a compound having an ether bond beta to a hydroxyl group, or a compound having an ether bond alpha to a carbonyl group, and wherein the solvent is preferably toluene.

[0051] In a further preferred embodiment, the reduction is carried out at a temperature of 20-80 °C, preferably at ambient temperature or 80 °C, most preferably at ambient temperature.

[0052] In a further preferred embodiment, a step of providing an alcohol and then converting the alcohol to a compound comprising a C=O bond is provided before step i), wherein said alcohol is preferably selected from a diol, primary alcohol and secondary alcohol, most preferably said alcohol is lignin.

[0053] In a further preferred embodiment, the object of the invention is attained by the products obtainable by the above preferred embodiments. Furthermore, the object of the invention is also attained by using said products as fuels.

DETAILED DESCRIPTION



[0054] Described herein is a method of conversion of a C-O or C=O bond to a C-H bond. The method, comprises the steps of (i) providing a compound comprising a C-O bond or a C=O bond, and then (ii) reducing the C-O or C=O bond to a C-H bond. A compound comprising a C=O bond is for example an aldehyde molecule and the C=O bond is in the method according to the present invention reduced to a C-H bond, i.e. the aldehyde is reduced to its corresponding hydrocarbon.

[0055] The method of conversion of a C-O or C=O bond to a C-H bond can also be used in a method of converting lignin to fuels. However, the lignin must first undergo oxidization and depolymerization to compounds having aldehyde groups. The resulting C=O moieties of the aldehyde groups are thereafter reduced C-H moieties. The final product may be used as fuels.

[0056] It is important to note that the oxidization reaction is not limited only to lignin. Other alcohols, including primary alcohols, secondary alcohols and diols can all be subjected to the oxidization reaction which yields an aldehyde. Moreover, diols such as lignin can also be oxidized to ketones.

[0057] The oxidization reaction, i.e. conversion of an alcohol to a compound comprising a C=O bond (i.e. aldehyde or ketone), involves oxidation with an oxidant and catalyst. The oxidant may be selected from H2O2, O2 and NaOCl, while the catalyst is selected from heterogeneous supported metal catalyst, homogeneous organometallic complex and a metal-free catalyst (mediator) and enzyme (EC 1:10:3:2). In the next step the compound comprising a C=O is reduced with a reducing agent and heterogeneous metal catalyst.

[0058] As already indicated, the alcohol (such as lignin) can be oxidized to an aldehyde or ketone. The conversion of the alcohol to an aldehyde is conducted in the presence of NaOCl, TEMPO (2,2,6,6-Tetramethylpiperidin-1-yl)oxyl), NaOH, KBr and O2 (see Examples 9-12). First, a solution of KBr is added to a solution comprising the alcohol and TEMPO. The mixture is then stirred and a basic NaOCl solution is added to the reaction mixture followed by adding NaOH to the reaction mixture in the presence of O2.

[0059] The alcohol is converted to a ketone in the presence of O2, TEMPO, HNO3 and HCl (see Example 8). The conversion involves adding TEMPO to the alcohol in the presence of O2. In the next step HNO3 and HCl are added to the mixture followed by heating.

[0060] When the alcohol is a diol, the diol is oxidized with oxidant and catalyst to an aldol which then undergoes a spontaneous catalytic retro-aldol reaction to the corresponding aldehyde moieties (see Examples 6 and 7). The C=O bonds of the aldehydes are subsequently reduced to a C-H bonds by the reducing agent and heterogeneous metal catalyst.

[0061] A preferred diol is lignin and derivatives thereof. The lignin may be selected from milled wood lignin, cellulosic lignin, organosolv lignin and technical lignin from pulping processes. The lignin is oxidized with oxidant and catalyst to a polymer comprising aldehyde groups which undergo spontaneous catalytic retro-aldol reaction which leads to a depolymerization (Example 13). In the subsequent step the aldehyde groups are reduced with reducing agent and heterogeneous metal catalyst. Moreover, the alcohol may be a primary alcohol which is first converted to an aldehyde and then the C=O group is reduced to a C-H bond. Primary alcohols may be selected from vanillyl alcohol, hydroxy-, methoxy- and ethoxybenzyl alcohols, and wherein vanillyl alcohol, hydroxy-, methoxy- and ethoxybenzyl alcohols.

[0062] A further alternative is to use a secondary alcohol which is first oxidized to a ketone wherein the C=O bond of the ketone is subsequently reduced to a C-H bond.

[0063] For the reduction step, the heterogeneous metal catalyst is a Pd(0)-nanocatalyst which is heterogeneously supported on silica containing material. The Pd-catalyst is selected from Pd(0)-amino functionalized silica support such as Pd(0)-AmP-silica support. Specific examples of Pd(0)-nanocatalyst are Pd(0)-AmP-MCF and Pd(0)-AmP-CPG (see Example 1). The Pd-catalyst is preferably recyclable (see Example 3 for recycling process).

[0064] The reducing agents for reducing the aldehyde or a ketone are ammonium formiate and H2 gas. The reduction can be carried in various temperatures such as at 20-80 °C. Although the reduction can be carried out at 80 °C, ambient temperature (i.e. room temperature of about 22 °C) is more convenient than and as effective as higher temperatures (see Example 1).

[0065] Importantly, the products obtained by the above described methods (particularly the method involving lignin) can be used as fuels.

[0066] It should be noted that the method of converting a C-O or C=O bond to a C-H bond does not necessarily have to involve an oxidation reaction. Instead of having an alcohol such as lignin as a starting compound, the starting compound may be a compound having a C-O or C=O bond such as an aldehyde, a ketone, an alcohol, an aldol, a compound having an ether bond beta to a hydroxyl group, or a compound having an ether bond alpha to a carbonyl group. The C-O or C=O bond is reduced to a C-H bond by a reducing agent and heterogeneous metal catalyst (see Examples 1, 2, 4 and 5).

[0067] The heterogeneous metal catalyst is a Pd(0)-nanocatalyst which is heterogeneously supported on silica containing material, preferably recyclable. Specific examples of these types of catalyst have already been mentioned above (see also Example 1) and the reducing agent is selected from hydrogen, formic acid and ammonium formiate (See Examples 2, 4 and 5). Alternatively, the catalyst may be a homogeneous organo-metallic complex which may have a complex comprising Pd, Ir, Ru, Ni, Co, Cu complexes (see Example 13).

[0068] The reducing agent is ammonium formiate and formic acid when the compound comprising a C-O bond is an alcohol (Example 2). However, the reducing agents are ammonium formiate and H2 gas when the compound comprising a C=O bond is an aldehyde (Example 5), ketone, an aldol, a compound having an ether bond beta to a hydroxyl group, or a compound having an ether bond alpha to a carbonyl group (Example 4).

[0069] The product obtainable by the above described reduction methods can be used as fuels.

EXAMPLES


General methods



[0070] (IR) spectra were recorded on Thermo Fisher Nicolet 6700 FT-IR spectrometer, nmax in cm-1. Bands are characterized as broad (br), strong (s), medium (m), or weak (w).

[0071] 1H NMR spectra were recorded on a Bruker Avance (500 MHz) spectrometer. Chemical shifts are reported in ppm from tetramethylsilane with the solvent resonance resulting from incomplete deuterium incorporation as the internal standard (CDCl3: δ 7.26 ppm). Data are reported as follows: chemical shift, multiplicity (s = singlet, d = doublet, q = quartet, br = broad, m = multiplet), and coupling constants (Hz), integration.

[0072] 13C NMR spectra were recorded on a Bruker Avance (125.8 MHz or 100 MHz) spectrometer with complete proton decoupling. Chemical shifts are reported in ppm from tetramethylsilane with the solvent resonance as the internal standard (CDCl3: δ 77.16 ppm).

[0073] High-resolution mass spectrometry was performed on Agilent 6520 Accurate-Mass Q-TOF LC/MS (positive mode).

[0074] Chemicals and solvents were either purchased puriss p. A. from commercial suppliers or were purified by standard techniques. Commercial reagents were used as purchased without any further purification.

[0075] Aluminum sheet silica gel plates (Fluka 60 F254) were used for thin-layer chromatography (TLC), and the compounds were visualized by irradiation with UV light (254 nm) or by treatment with a solution of phospho-molybdic acid (25 g), Ce(SO4)2·H2O (10 g), conc. H2SO4 (60 mL), and H2O (940 mL), followed by heating. Purification of the product was carried out by flash column chromatography using silica gel (Fluka 60, particle size 0.040-0.063 mm).

Reference Example 1 - Optimization studies (Table 1)



[0076] A microwave-vial containing a solution of 1a (0.4 mmol, 1.0 equiv.), ammonium formiate and Pd(0)-Nanocatalyst (palladium-aminopropyl-mesocellular foam (Pd(0)-AmP-MCF), 26.8 mg, 0.02 mmol, 8 wt%, 5 mol%) [1] or (palladium-aminopropyl-controlled pore glass (Pd(0)-CPG), 569Å, 148.0 mg, 0.02 mmol, 135 µmol/g) in EtOH (2.4 mL) and H2O (0.6 mL) was stirred for 10 minutes at room temperature. Afterwards was added formic acid and the resulting mixture was stirred at room temperature for the time shown in table. NMR samples for NMR-yield were prepared by removing 0.05 mL aliquots from the reaction mixture, filtration through Celite using CDCl3 (1.5 mL) as eluent and mesitylene was used as an internal standard.
Table 1


EntryPd catalystHCOONH4 (equiv.)HCO2H (equiv.)temp (°C)time (h)Conv.(%)a
1 Pd/C 0.25 3.3 80 1 50[e]
2 Pd(0)-AmP-MCF 0.25 3.3 80 0.5 78
3 Pd(0)-AmP-MCF 0.25 3.3 100 0.5 69
4 Pd(0)-AmP-MCF 0.50 3.3 80 0.5 74
5b Pd(0)-AmP-MCF 0.25 3.3 80 0.5 49
6c Pd(0)-AmP-MCF 0.25 3.3 80 0.5 53
7 Pd(0)-AmP-CPG 0.25 3.3 80 0.5 54
8 Pd(0)-AmP-MCF 0.25 - 80 0.5 <1
9 Pd(0)-AmP-MCF 3.0 - 80 0.5 45
10 Pd(0)-AmP-MCF 0.25 6.6 80 0.5 94
11 Pd(0)-AmP-CPG 0.25 6.6 80 0.5 51
12 Pd(0)-AmP-MCF 0.25 6.6 22 1 >99
13 Pd(0)-AmP-CPG 0.25 6.6 22 1 >99
14 Pd/C 0.25 6.6 22 1 41[e]
15d Pd(0)-AmP-MCF 3.0 - 22 24 8
16d Pd(0)-AmP-MCF 3.0 - 80 9 >99
17 Pd(0)-AmP-MCF - 6.6 22 1 52
18 Pd(0)-AmP-MCF 0.25 6.0 22 1  
19 Pd(0)-AmP-MCF 0.25 5.0 22 1 >99
[a] Determined by analysis of 1H-NMR of unpurified mixtures. [b] 10 mol% MCF-Pd(0). [c] 2.5 mol% MCF-Pd(0). [d] The reaction was performed with toluene. [e]The same conv after 24h.

Reference Example 2 - Examples of converting alcohols to hydrocarbon (Table 2)



[0077] 



[0078] Procedure: A microwave-vial containing a solution of 1 (0.4 mmol, 1.0 equiv.), ammonium formiate (6.0 mg, 0.095 mmol, 25mol%) and Pd(0)-Nanocatalyst (Pd(0)-AmP-MCF, 26.8 mg, 0.02 mmol, 8 wt%, 5 mol%) [2] or (Pd(0)-CPG, 569Å, 148.0 mg, 0.02 mmol, 135 µmol/g) in EtOH (2.4 mL) and H2O (0.6 mL) was stirred for 10 minutes at room temperature. Afterwards was added formic acid (0.09 mL, 2.4 mmol, 6 equiv.) and the resulting mixture was stirred at room temperature for the time shown in table. NMR samples for NMR-yield were prepared by removing 0.05 mL aliquots from the reaction mixture, filtration through Celite using CDCl3 (1.5 mL) as eluent and mesitylene was used as an internal standard. Before the purification of the products, the crude reaction mixture was filtrated through Celite using CHCl3 (10 mL) as eluent and evaporated. The crude material was purified by silica gel flash column chromatography.
Table 2


EntryPd catalystAlcoholProducttime (h)Yield.(%)a
1 Pd(0)-AmP-MCF



1 95
2 Pd(0)-AmP-CPG 1 93b
4 Pd(0)-AmP-MCF



1 93b
5 Pd(0)-AmP-MCF



4 96
6 Pd(0)-AmP-MCF



1 94b
7 Pd(0)-AmP-CPG 1 91b
8 Pd(0)-AmP-MCF



1 96b
9 Pd(0)-AmP-MCF

1 93
10 Pd(0)-AmP-MCF

8 98b
11 Pd(0)-AmP-MCF



1 97
12 Pd(0)-AmP-MCF



1 92
13 Pd(0)-AmP-MCF



3 91b
14 Pd(0)-AmP-CPG 3 90b
[a] Isolated yield of pure 2. [b] H-NMR yield using mesitylene as internal standard.

Characterization of products


Toluene



[0079] 



[0080] Spectra identical to the reported [3]; 1H NMR (500 MHz, CDCl3): d 7.20-7.15 (m, 2H), 7.11-7.05 (m, 3H), 2.28 (s,3H).

p-toluidine



[0081] 



[0082] Spectra identical to the reported [4]; 1H NMR (500 MHz, CDCl3): d 6.93 (d, J = 8.7 Hz, 2H), 6.62 (d, J = 8.6 Hz, 2H), 2.18 (s,3H).

1,2-dimethoxy-3-methylbenzene



[0083] 



[0084] Colorless oil; IR (neat) n 2935 (m), 2834 (w), 1586 (m), 1484 (s), 1425 (m), 1268 (s), 1222 (s), 1174 (m), 1081 (s), 1009 (s), 805 (w), 747 (s), 686 (m); 1H NMR (500 MHz, CDCl3): d 6.95 (t, J = 8.2 Hz, 1H), 6.78-6.75 (m, 2H), 3.85 (s, 3H), 3.80 (s, 3H), 2.28 (s,3H); 13C NMR (125.8 MHz, CDCl3): d 152.9, 147.5, 132.2, 123.8, 123.0, 110.1, 60.2, 55.8, 15.9; HRMS (ESI+) [M+H]+ calcd for C9H13O2: 153.0916, found: 153.0906;

2-methoxy-4-methylphenol



[0085] 



[0086] Colorless oil; IR (neat) n 3511 (b), 2923 (m), 1608 (w), 1514 (s), 1464 (m), 1364 (w), 1271 (s), 1234 (m), 1206 (m), 1150 (m), 1122 (w), 1034 (m), 919 (w), 810 (m), 590 (w), 559 (w) cm-1; 1H NMR (500 MHz, CDCl3): d 6.83 (d, J = 7.9 Hz, 1H), 6.71-6.67 (m, 2H), 5.45 (s, 1H), 3.89 (s, 3H), 2.31 (s,3H); 13C NMR (125.8 MHz, CDCl3): d 146.2, 143.3, 129.6, 121.5, 114.1, 111.6, 55.8, 21.0; HRMS (ESI+) [M+H]+ calcd for C8H11O2: 139.0759, found: 139.0752;

1-ethylbenzene



[0087] 



[0088] Spectra identical to the reported [5]; 1H NMR (500 MHz, CDCl3): d 7.28 (m, 2H). 7.18 (m, 3H), 2.65 (q, 2H, J = 7.5 Hz), 1.24 (t, 3H, J = 7.5 Hz).

4-ethylbenzenamine



[0089] 



[0090] Brown solid; IR (neat) n 3354 (b), 2963 (m), 2929 (m), 2870 (m), 2360 (w), 1686 (s), 1612 (m), 1516 (s), 1455 (w), 1411 (m), 1310 (m), 1180 (w), 1123 (w), 827 (m), 755 (m), 474 (w) cm-1; 1H NMR (500 MHz, CDCl3): d 7.03 (d, J = 8.4 Hz, 2H), 6.69 (d, J = 8.4 Hz, 2H), 5.79 (s, 2H), 2.57 (m, 2H), 1.21 (t, J = 7.6 Hz, 3H); 13C NMR (125.8 MHz, CDCl3): d 128.3, 128.3, 128.2, 120.3, 119.3, 118.0, 28.0, 15.5; HRMS (ESI+) [M+H]+ calcd for C8H12N 122.0969, found: 122.0965.

1-ethyl-4-methoxybenzene



[0091] 



[0092] Spectra identical to the reported [6]; 1H NMR (500 MHz, CDCl3): 7.11 (d, J = 8.5 Hz, 2H), 6.83 (d, J = 8.5 Hz, 2H), 3.78 (s, 3H), 2.59 (q, J = 7.6 Hz, 2H), 1.21 (t, J= 7.6 Hz, 3H).

Diphenylmethane



[0093] 



[0094] White solid; IR (neat) n 3060 (w), 3025 (w), 2907 (w), 2842 (w), 1598 (w), 1492 (m), 1450 (m), 1075 (w), 1028 (w), 729 (s), 715 (s), 606 (m), 551 (w), 456 (m) cm-1; 1H NMR (500 MHz, CDCl3): d 7.34-7.27 (m,4H), 7.24-7.18 (m,6H), 4.00 (s, 2H); 13C NMR (125.8 MHz, CDCl3): d 141.3, 129.1 (4C), 128.6 (4C), 126.2 (3C), 42.1; HRMS (ESI+) [M-H]+ calcd for C13H11 167.0861, found: 167.0854.

Triphenylmethane



[0095] 



[0096] White solid; IR (neat) n 3462 (b), 3060 (w), 1596 (w), 1489 (m), 1443 (m), 1326 (w), 1154 (m), 1068 (w), 1007 (m), 889 (m), 755 (s), 694 (s), 636 (s), 581 (m), 466 (m) cm-1; 1H NMR (500 MHz, CDCl3): d 7.36-7.30 (m,15H), 2.82 (s, 1H); 13C NMR (125.8 MHz, CDCl3): d 146.8, 128.6- 127.23 (m), 82.0; HRMS (ESI+) [M-H]+ calcd for C19H15 243.1174, found: 243.1168.

1-propylbenzene



[0097] 



[0098] Spectra identical to the reported [7]. 1H NMR (500 MHz, CDCl3)[7]: 7.42-7.04 (m, 5H), 2.49 (t, 2H), 2.05-1.82 (m, 2H), 0.9 (t, 3H).

Reference Example 3 - Procedure for the recycling of the Pd nanoparticles (Table 3)



[0099] A microwave-vial containing a solution of 1a (61.7 mg, 0.4 mmol, 1.0 equiv.), ammonium formiate (6.0 mg, 0.095 mmol, 25mol%) and Pd(0)-Nanocatalyst (Pd(0)-AmP-MCF, 26.8 mg, 0.02 mmol, 8 wt%, 5 mol%) [8] or (Pd(0)-CPG, 569Å, 148.0 mg, 0.02 mmol, 135 µmol/g) in EtOH (2.4 mL) and H2O (0.6 mL) was stirred for 10 minutes at room temperature. Afterwards was added formic acid (121.6 mg, 0.1 mL, 2.64 mmol, 6.6 equiv.) and the resulting mixture was stirred at room temperature for 1h. Next, the reaction mixture was transferred to a centrifuge-vial and EtOH (8 mL) was added and after centrifugation, the supernatant liquid was removed and the catalyst washed with EtOH (8 mL) 3 times. Afterwards the catalyst was dried under vacuum and then washed with CH2Cl2 (8 mL) three times and then dried under vacuum.
Table 3.


CycleTime (h)Conv.(%)a
1 1 >99 (95% yield)b
2 1 >99
3 1 >99
4 1 >99
5 1 >99
6 1 98
[a] Determined by analysis of 1H-NMR of unpurified mixtures.
[b] pure isolated 2a

Reference Example 4 - Example of ether cleavage



[0100] 


Example 5 - Example of deoxygenation of aldehydes



[0101] A microwave-vial containing a solution of aldehyde (0.1 mmol, 1.0 equiv.), ammonium formiate (18.9 mg, 0.3 mmol, 3.0 equiv.) and Pd(0)-Nanocatalyst (Pd(0)-AmP-MCF, 6.7 mg, 0.005 mmol, 8 wt%, 5 mol%) in toluene (0.5 mL) under H2 conditions was stirred at 80 °C for 6h.


Example 6 - General procedure for selective oxidation/depolymerization sequence



[0102] 



[0103] A solution of KBr (1.2 mg, 0.01 mmol, 10 mol %) in water (1mL) were added to a solution containing lignin model (0.1 mmol, 1.0 equiv.) and TEMPO (1.6 mg, 0.01 mmol, 10 mol %) in CH2Cl2 (4mL) and stirred at 0 °C. Then, NaOCl (5.3 g, 10 mmol, 100 equiv.) solution with pH 9 was added drop wise to the reaction mixture. Afterwards, was added NaOH (2M, 3mL) to the reaction mixture and connected balloon with O2 and stirred at 0 °C for 3h. After this time, the aqueous layer was extracted two times with CH2Cl2 and the combined organic layers were washed with H2O two times, dried over anhydrous Na2SO4 and concentrated under reduced pressure. The crude material was purified by silica gel flash column chromatography obtaining the major product (Cl product): 1H NMR (500 MHz, CDCl3): d 10.32 (s, 1H), 7.41 (s, 1H), 6.90 (s, 1H), 3.97 (s, 3H), 3.92 (s, 3H). 13C NMR (125.8 MHz, CDCl3): d 188.7, 154.5, 148.4, 132.0, 125.4, 112.4, 109.77, 56.5, 56.2.

Example 7 - Procedure for selective oxidation/depolymerization/deoxygenation sequence



[0104] A solution of KBr (1.2 mg, 0.01 mmol, 10 mol %) in water (1mL) were added to a solution containing "diol lignin model" (0.1 mmol, 1.0 equiv.) and TEMPO (1.6 mg, 0.01 mmol, 10 mol %) in CH2Cl2 (4mL) and stirred at 0 °C. Then, NaOCl (5.3 g, 10 mmol, 100 equiv.) solution with pH 9 was added drop wise to the reaction mixture. Afterwards, was added NaOH (2M, 3mL) to the reaction mixture and connected balloon with O2 and stirred at 0 °C for 3h. After this time, the aqueous layer was extracted two times with CH2Cl2. The solvent was removed. Ammonium formiate (18.9 mg, 0.3 mmol, 3.0 equiv.) and Pd(0)-Nanocatalyst (Pd(0)-AmP-MCF, 6.7 mg, 0.005 mmol, 8 wt%, 5 mol%) and toluene (0.5 mL) were added. The reaction was stirred at 80 °C for 6h under H2 atmosphere.


Example 8 - General procedure for the TEMPO oxidation to ketone



[0105] A microwave vial was loaded with diol 3 (33.4 mg, 0.1 mmol, 1.0 equiv.) and TEMPO (0.8 mg, 0.005 mmol, 5 mol%) and flushed with oxygen using O2-balloon for 5 minutes, followed by addition of 100 µL of a solution from a mixture of 10 µL of HNO3 in 1 mL acetonitrile and then 100 µL of a solution from a mixture of 10 µL HCl in 1 mL acetonitrile. Afterwards acetonitrile (300 µL) and water (30 µL) was added and then the vial was sealed and heated to 45 °C for 20h. Subsequently, the organic phase was separated and water phase was washed with CH2Cl2. The collected organic phases were dried over Na2SO4, and concentrated by reduced pressure. The crude material was further purified by silica chromatography giving pure products 8 in 99% yield.


Example 9 - Screening TEMPO oxidation of dimethoxy benzyl alcohol



[0106] To a solution of alcohol 1 (16.8 mg, 0.1 mmol, 1.0 equiv.) in 4 mL of CH2Cl2 and TEMPO (1.6 mg, 0.01 mmol, 10 mol%), an aqueous solution of KBr (1.2 mg, 0.01 mmol, 10 mol%, in 1 mL water) was added at 0 °C and the reaction mixture was stirred at 0 °C. The fresh aqueous solution of NaClO (14% aq.) (2.7 g, 5 mmol, 50 equiv. or 0.53 g, 1 mmol, 10 equiv.) by adjusting pH at 9 with saturated NaHCO3. Afterwards 2 M NaOH (3 mL) was added slowly. The reaction mixture was stirred for 1h or 24h in presence of O2 gas at 0 °C. Afterwards the organic phase was separated and water phase was washed with CH2Cl2. The collected organic phases were dried over Na2SO4, and concentrated by reduced pressure. The crude material was further purified by silica chromatography giving pure products 5.


entryNaOCl (equiv.)timeyieldbRatio (5a:5b:5c)c
1d,e 10 24 n.d 86:4:10 (52: 37: 11)f
2d,e 50 1 83 48:52:0
3d,e 50 1 87 19:75:6
4 10 24 n.d 86:4:10
5e 50 1 85 54:30:16 (35: 65:0)f
[a] According to 1H NMR the conversion of all reactions were 100%. [b] Yield of purified product 5 after silica chromatography. [c] Determined by 1H NMR analysis of crude reaction mixture [d] The reaction was run without O2 balloon. [e] The reaction mixture was neutralizied to pH 7 before workup. [f] The ratios of the products changed after work up.

Example 10 - Screening TEMPO oxidation of lignin model



[0107] To a solution of diol 3 (33.4 mg, 0.1 mmol, 1.0 equiv.) in 4 mL of CH2Cl2 and TEMPO (1.6 mg, 0.01 mmol, 10 mol%), an aqueous solution of KBr (1.2 mg, 0.01 mmol, 10 mol%, in 1 mL water) was added at 0 °C and the reaction mixture was stirred at 0 °C. The fresh aqueous solution of NaClO (14% aq.) (2.7 g, 5 mmol, 50 equiv. or 0.53 g, 1 mmol, 10 equiv.) by adjusting pH at 9 with saturated NaHCO3. Afterwards 2 M NaOH (3 mL) was added slowly. The reaction mixture was stirred for 1h or 24h in presence of O2 gas at 0 °C. After-wards the organic phase was separated and water phase was washed with CH2Cl2. The collected organic phases were dried over Na2SO4, and concentrated by reduced pressure. The crude material was further purified by silica chromatography giving pure products 5 and 8.


entryNaOCl (equiv.)timeyieldbRatio (5a:5b:8)c
1d,e 10 24 n.d 100:0:0
2d,f 50 1 52 21:70:9
3d 50 1 50 37:38:25
4 50 1 51 29:51:20
[a] According to 1H NMR the conversion of all reactions were 100%. [b] Yield of purified product 5 and 8 after silica chromatography. [c] Determined by 1H NMR analysis of crude reaction mixture [d] The reaction was run without O2 balloon. [e] the conversion of reaction was 20 %. [f] The reaction mixture was neutralizied to pH 7 before workup.

Example 11 - Screening TEMPO oxidation of two substituted lignin models



[0108] To a solution of alcohol 1 or diol 3 (0.1 mmol, 1.0 equiv.) in 4 mL of CH2Cl2 and TEMPO (1.6 mg, 0.01 mmol, 10 mol%), an aqueous solution of KBr (1.2 mg, 0.01 mmol, 10 mol%, in 1 mL water) was added at 0 °C and the reaction mixture was stirred at 0 °C. The fresh aqueous solution of NaClO (14% aq.) (2.7 g, 5 mmol, 50 equiv.) by adjusting pH at 9 with saturated NaHCO3. Afterwards 2 M NaOH (3 mL) was added slowly. The reaction mixture was stirred for 1h in presence of O2 gas at 0 °C. Afterwards the organic phase was separated and water phase was washed with CH2Cl2. The collected organic phases were dried over Na2SO4, and concentrated by reduced pressure. The crude material was further purified by silica chromatography giving pure products 4.


entrysubstrateNaOCl (equiv.)timeyieldbRatio (4a:4b:4c:4d)c
1 1a

50 1 85 54:30:16
2 1b

50 1 70 38:54:8
3 3a

50 1 51 29:51:0:20
4 3b

50 1 50 60:40: 0:0
[a] According to 1H NMR the conversion of all reactions were 100%. [b] Yield of purified product 4 after silica chromatography. [c] Determined by 1H NMR analysis of crude reaction mixture

Example 12 - TEMPO oxidation of three substituted lignin models



[0109] To a solution of alcohol 1 or diol 3 (0.1 mmol, 1.0 equiv.) in 4 mL of CH2Cl2 and TEMPO (1.6 mg, 0.01 mmol, 10 mol%), an aqueous solution of KBr (1.2 mg, 0.01 mmol, 10 mol%, in 1 mL water) was added at 0 °C and the reaction mixture was stirred at 0 °C. The fresh aqueous solution of NaClO (14% aq.) (2.7 g, 5 mmol, 50 equiv.) by adjusting pH at 9 with saturated NaHCO3. Afterwards 2 M NaOH (3 mL) was added slowly. The reaction mixture was stirred for 1h in presence of O2 gas at 0 °C. Afterwards the organic phase was separated and water phase was washed with CH2Cl2. The collected organic phases were dried over Na2SO4, and concentrated by reduced pressure. The crude material was further purified by silica chromatography giving pure products 7.


entrysubstrateNaOCl (equiv.)timeyieldbRatio (7a:7b:7c)c
1 5a

50 1 74 8:80:12
2 5b

50 1 75 0:51:49
3 6a

50 1 53 0:80:20
4 6b

50 1 52 0:100:0
[a] According to 1H NMR the conversion of all reactions were 100%. [b] Yield of purified product 7 after silica chromatography. [c] Determined by 1H NMR analysis of crude reaction mixture

Example 13 - Procedure for selective oxidation/depolymerization/deoxygenation sequence of lignins (containing benzylic, allylic or aliphatic alcohols including β-O-4 aryl ether linkages):



[0110] A solution of KBr (1.2 mg, 0.01 mmol, 10 mol %) in water (1mL) were added to a solution containing lignin (0.1 mmol, 1.0 equiv.) and TEMPO (1.6 mg, 0.01 mmol, 10 mol %) in CH2Cl2 (4mL) and stirred at 0 °C. Then, NaOCI (5.3 g, 10 mmol, 100 equiv.) solution with pH 9 was added drop a drop to the reaction mixture. Afterwards, was added NaOH (2M, 3mL) to the reaction mixture and connected balloon with O2 and stirred at 0 °C for 3h. After this time, the aqueous layer was extracted two times with CH2Cl2. The solvent was removed. Ammonium formate (18.9 mg, 0.3 mmol, 3.0 equiv.) and Pd(0)-Nanocatalyst (Pd(0)-AmP-MCF, 6.7 mg, 0.005 mmol, 8 wt%, 5 mol%) and toluene (0.5 mL) were added. The reaction was stirred at 80 °C for 6h under H2 atmosphere.

[0111] Lignin (containing benzylic, allylic or aliphatic alcohols including β-O-4 aryl ether linkages) was employed as substrates. The lignin can be milled wood lignin (MWL), cellulolytic enzyme lignin (CEL), organosolv lignin or a technical lignin from the pulping processes.

[0112] The selective oxidation/depolymerization/deoxygenation sequence of lignins can be employed using different transition metal (e.g. Pd, Ir, Ru, Ni, Co, Cu) complexes.

REFERENCES


References for BACKGROUN OF INVENTION



[0113] 
  1. [1] V.S. Ranade, R. Prins, Chem. Eur. J. 2000, 6, 313.
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References for the EXAMPLE section of the DETAILED DESCRIPTION



[0114] 
  1. 1.
    1. a) E. W. Ping, R. Wallace, J. Pierson, T. F. Fuller and C. W. Jones, Micropor. Mesopor. Mater., 2010, 132, 174-180
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    3. c) E. V. Johnston, O. Verho, M. D. Kärkäs, M. Shakeri, C. Tai, P. Palmgren, K. Eriksson, S. Oscarsson and J. Bäckvall, Chem. Eur. J., 2012, 18, 12202-12206
    4. d) L. Deiana, S. Afewerki, C. Palo-Nieto, O. Verho, E. V. Johnston and A. Córdova, Sci. Rep., 2012, 2, 851.; DOI:10.1038/srep00851
  2. 2.
    1. a) E. W. Ping, R. Wallace, J. Pierson, T. F. Fuller and C. W. Jones, Micropor. Mesopor. Mater., 2010, 132, 174-180
    2. b) M. Shakeri, C. Tai, E. Göthelid, S. Oscarsson and J. Bäckvall, Chem. Eur. J., 2011, 17, 13269-13273
    3. c) E. V. Johnston, O. Verho, M. D. Kärkäs, M. Shakeri, C. Tai, P. Palmgren, K. Eriksson, S. Oscarsson and J. Bäckvall, Chem. Eur. J., 2012, 18, 12202-12206
    4. d) L. Deiana, S. Afewerki, C. Palo-Nieto, O. Verho, E. V. Johnston and A. Córdova, Sci. Rep., 2012, 2, 851.; DOI:10.1038/srep00851
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  4. 4. Berger et al., Magnetic Resonance in Chemistry, 2013, 51(12), 815.
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  8. 8.
    1. a) E. W. Ping, R. Wallace, J. Pierson, T. F. Fuller and C. W. Jones, Micropor. Mesopor. Mater., 2010, 132, 174-180
    2. b) M. Shakeri, C. Tai, E. Göthelid, S. Oscarsson and J. Bäckvall, Chem. Eur. J., 2011, 17, 13269-13273
    3. c) E. V. Johnston, O. Verho, M. D. Kärkäs, M. Shakeri, C. Tai, P. Palmgren, K. Eriksson, S. Oscarsson and J. Bäckvall, Chem. Eur. J., 2012, 18, 12202-12206
    4. d) L. Deiana, S. Afewerki, C. Palo-Nieto, O. Verho, E. V. Johnston and A. Córdova, Sci. Rep., 2012, 2, 851.; DOI:10.1038/srep00851



Claims

1. Method of conversion of a C=O bond to a C-H bond, comprising the steps of:

i. Providing an alcohol and converting the alcohol to a compound comprising a C=O bond, wherein the compound comprising a C=O is selected from an aldehyde and a ketone, wherein the conversion of the alcohol to a compound comprising a C=O bond comprises the step of:

- Oxidation with an oxidant and catalyst, wherein the oxidant is selected from H2O2, O2 and NaOCl, and wherein the catalyst is selected from heterogeneous supported metal catalyst, homogeneous organometallic complex, metal-free catalyst (mediator), and enzyme (EC 1:10:3:2) and

ii. Providing the compound comprising a C=O bond from the previous step, and

iii. Reducing said compound comprising a C=O bond in a solvent comprising reducing agent and a catalyst, wherein the reducing agent is selected from ammonium formate, formic acid and H2 gas, and wherein the catalyst is selected from a heterogeneous metal catalyst wherein the heterogeneous metal catalyst is a Pd(0)-nanocatalyst which is heterogeneously supported on silica containing material selected from Pd(0)-amino functionalized silica support.


 
2. Method according to claim 1, wherein the catalyst is a Pd-catalyst is a Pd(0)-AmP-silica support selected from Pd(0)-AmP-MCF and Pd(0)-AmP-CPG, preferably the Pd-catalyst is recyclable.
 
3. Method according to any one of the previous claims, wherein the reducing agents are ammonium formiate and H2 gas, and wherein the solvent is preferably toluene.
 
4. Method according to any one of previous claims, wherein the reduction is carried out at a temperature of 20-80 °C, preferably at ambient temperature or 80 °C.
 
5. Method according to any one of previous claims, wherein the alcohol is converted to an aldehyde in step i), wherein the conversion of the alcohol to an aldehyde is conducted in the presence of NaOCl, TEMPO (2,2,6,6-Tetramethylpiperidin-1-yl)oxyl), NaOH, KBr and O2.
 
6. Method according to the previous claim, wherein step i) comprises the steps of:

a. Adding a solution of KBr to a solution comprising the alcohol and TEMPO, preferably KBR is in a water solution and TEMPO is in CH2Cl2,

b. Stirring the mixture, preferably at 0 °C,

c. NaOCl solution is added to the reaction mixture, preferably the NaOCl solution has pH 9,

d. Adding NaOH to the reaction mixture in the presence of O2, and

e. Stirring the mixture, preferably at 0 °C, more preferably at 0 ° for 3 hours.


 
7. Method according to claims 1-5, wherein the alcohol is converted to a ketone in step i), wherein the conversion of the alcohol to a ketone is conducted in the presence of O2, TEMPO, HNO3 and HCl.
 
8. Method according to any one of the previous claims 1-6, wherein the alcohol is a diol, and wherein said diol is in step i) converted to an aldol which then undergoes a spontaneous catalytic retro-aldol reaction to the corresponding aldehyde moieties, and wherein the C=O bond of the aldehydes are subsequently reduced to a C-H bond in step iii).
 
9. Method according to the previous claim, wherein the diol is selected from lignin and derivatives thereof, preferably the alcohol is lignin containing benzylic, allylic or aliphatic alcohols including β-O-4 aryl ether linkages, more preferably the lignin is selected from milled wood lignin, cellulolytic lignin, organosolv lignin and technical lignin from pulping processes.
 
10. Method according to the previous claim, comprising the steps of:

i. Providing lignin and oxidizing the lignin to a polymer comprising aldehyde groups,

ii. The polymer comprising aldehyde groups which have been provided in the previous step subsequently undergo spontaneous catalytic retra-aldol reaction which leads to a depolymerization,

iii. Reducing the aldehyde groups.


 
11. Method according to anyone of the previous claims 1-6, wherein the alcohol is a primary alcohol, and wherein the primary alcohol is converted to an aldehyde in step i), and wherein the C=O bond of the aldehyde is subsequently reduced to a C-H bond.
 
12. Method according to any one of the previous claims 1-6, wherein the alcohol is selected from vanillyl alcohol, hydroxy-, methoxy- and ethoxybenzyl alcohols, and wherein vanillyl alcohol, hydroxy-, methoxy- and ethoxybenzyl alcohols are converted to their respective aldehydes in step i), and wherein the C=O bond of the aldehyde is subsequently reduced to a C-H bond.
 
13. Method according to any one of the previous claims 1-6, wherein the alcohol is a secondary alcohol, and wherein said secondary alcohol is converted to a ketone in step i), and wherein the C=O bond of the ketone is subsequently reduced to a C-H bond.
 


Ansprüche

1. Verfahren zur Umwandlung einer C=O-Bindung in eine C-H-Bindung, umfassend die Schritte:

i. Bereitstellen eines Alkohols und Umwandeln des Alkohols in eine Verbindung, welche eine C=O-Bindung umfasst, wobei die Verbindung, die ein C=O umfasst, aus einem Aldehyd und einem Keton ausgewählt ist, wobei die Umwandlung des Alkohols in eine Verbindung, die eine C=O-Bindung umfasst, den Schritt umfasst:

- Oxidation mit einem Oxidationsmittel und einem Katalysator, wobei das Oxidationsmittel aus H2O2, O2 und NaOCl ausgewählt ist und wobei der Katalysator aus einem heterogenen geträgerten Metallkatalysator, einem homogenen metallorganischen Komplex, metallfreiem Katalysator (Mediator) und Enzym (EC 1:10:3:2) ausgewählt ist und

ii. Bereitstellen der Verbindung, die eine C=O-Bindung umfasst, aus dem vorhergehenden Schritt und

iii. Reduzieren der Verbindung, die eine C=O-Bindung umfasst, in einem Lösungsmittel, welches Reduktionsmittel und einen Katalysator umfasst, wobei das Reduktionsmittel aus Ammoniumformiat, Ameisensäure und H2-Gas ausgewählt ist und wobei der Katalysator aus einem heterogenen Metallkatalysator ausgewählt ist, wobei der heterogene Metallkatalysator ein Pd(0)-Nanokatalysator ist, der heterogen auf einem Siliciumdioxid-haltigen Material geträgert ist, ausgewählt aus Pd(0)-aminofunktionalisiertem Siliciumdioxid-Träger.


 
2. Verfahren nach Anspruch 1, wobei der Katalysator ein Pd-Katalysator ist, ein Pd(0)-AmP-Siliciumdioxid-Träger, ausgewählt aus Pd(0)-AmP-MCF und Pd(0)-AmP-CPG, wobei der Pd-Katalysator vorzugsweise recyclingfähig ist.
 
3. Verfahren nach einem der vorhergehenden Ansprüche, wobei die Reduktionsmittel Ammoniumformiat und H2-Gas sind und wobei das Lösungsmittel vorzugsweise Toluol ist.
 
4. Verfahren nach einem der vorhergehenden Ansprüche, wobei die Reduktion bei einer Temperatur von 20 °C bis 80 °C durchgeführt wird, vorzugsweise bei Umgebungstemperatur oder 80 °C.
 
5. Verfahren nach einem der vorhergehenden Ansprüche, wobei im Schritt i) der Alkohol in einen Aldehyd umgewandelt wird, wobei die Umwandlung des Alkohols in einen Aldehyd in Gegenwart von NaOCl, TEMPO (2,2,6,6-Tetramethylpiperidin-1-yl)oxyl), NaOH, KBr und O2 durchgeführt wird.
 
6. Verfahren nach dem vorhergehenden Anspruch, wobei der Schritt i) die Schritte umfasst:

a. Zugeben einer Lösung von KBr zu einer Lösung, welche den Alkohol und TEMPO umfasst, wobei vorzugsweise KBr in einer wässrigen Lösung vorliegt und TEMPO in CH2Cl2 vorliegt,

b. Rühren des Gemisches, vorzugsweise bei 0 °C,

c. NaOCl-Lösung wird zu dem Reaktionsgemisch gegeben, vorzugsweise weist die NaOCl-Lösung einen pH-Wert von 9 auf,

d. Zugeben von NaOH zu dem Reaktionsgemisch in Gegenwart von O2 und

e. Rühren des Gemisches, vorzugsweise bei 0 °C, insbesondere 3 Stunden lang bei 0 °C.


 
7. Verfahren nach Anspruch 1 bis 5, wobei im Schritt i) der Alkohol in ein Keton umgewandelt wird, wobei die Umwandlung des Alkohols in ein Keton in Gegenwart von O2, TEMPO, HNO3 und HCl durchgeführt wird.
 
8. Verfahren nach einem der vorhergehenden Ansprüche 1 bis 6, wobei der Alkohol ein Diol ist und wobei das Diol im Schritt i) in ein Aldol umgewandelt wird, welches dann eine spontane katalytische Retro-Aldol-Reaktion zu den entsprechenden Aldehyd-Einheiten durchläuft, und wobei die C=O-Bindung der Aldehyde anschließend im Schritt iii) zu einer C-H-Bindung reduziert wird.
 
9. Verfahren nach dem vorhergehenden Anspruch, wobei das Diol aus Lignin und Derivaten davon ausgewählt ist, es sich bei dem Alkohol vorzugsweise um Lignin-haltige Benzyl-, Allyl- oder aliphatische Alkohole handelt, die β-O-4-Arylether-Bindungen umfassen, wobei insbesondere das Lignin aus Holzspan-Lignin, cellulolytischem Lignin, Organosolv-Lignin und technischem Lignin aus Aufschlussverfahren ausgewählt ist.
 
10. Verfahren nach dem vorhergehenden Anspruch, umfassend die Schritte:

i. Bereitstellen von Lignin und Oxidieren des Lignins zu einem Polymer, welches Aldehyd-Gruppen umfasst,

ii. das Polymer, das Aldehyd-Gruppen umfasst, welches in dem vorhergehenden Schritt bereitgestellt worden ist, durchläuft anschließend eine spontane katalytische Retro-Aldol-Reaktion, welche zu einer Depolymerisation führt,

iii. Reduzieren der Aldehyd-Gruppen.


 
11. Verfahren nach einem der vorhergehenden Ansprüche 1 bis 6, wobei der Alkohol ein primärer Alkohol ist und wobei der primäre Alkohol im Schritt i) in einen Aldehyd umgewandelt wird und wobei die C=O-Bindung des Aldehyds anschließend zu einer C-H-Bindung reduziert wird.
 
12. Verfahren nach einem der vorhergehenden Ansprüche 1 bis 6, wobei der Alkohol aus Vanillylalkohol, Hydroxy-, Methoxy- und Ethoxybenzylalkoholen ausgewählt ist und wobei im Schritt i) Vanillylalkohol, Hydroxy-, Methoxy- und Ethoxybenzylalkohole in ihre entsprechenden Aldehyde umgewandelt werden und wobei die C=O-Bindung des Aldehyds anschließend zu einer C-H-Bindung reduziert wird.
 
13. Verfahren nach einem der vorhergehenden Ansprüche 1 bis 6, wobei der Alkohol ein sekundärer Alkohol ist und wobei der sekundäre Alkohol im Schritt i) in ein Keton umgewandelt wird und wobei die C=O-Bindung des Ketons anschließend zu einer C-H-Bindung reduziert wird.
 


Revendications

1. Procédé de conversion d'une liaison C=O en une liaison C-H, comprenant les étapes de :

i. fourniture d'un alcool et de conversion de l'alcool en un composé comprenant une liaison C=O, le composé comprenant une liaison C=O étant choisi parmi un aldéhyde ou une cétone, la conversion de l'alcool en un composé comprenant une liaison C=O comprenant l'étape :

- d'oxydation avec un oxydant et un catalyseur, l'oxydant étant choisi parmi H2O2, O2 et NaOCl, et le catalyseur étant choisi parmi un catalyseur métallique à support hétérogène, un complexe organométallique homogène, un catalyseur exempt de métal (médiateur) et une enzyme (EC 1:10:3:2) et

ii. de fourniture du composé comprenant une liaison C=O provenant de l'étape précédente, et

iii. de réduction dudit composé comprenant une liaison C=O dans un solvant comprenant un agent de réduction et un catalyseur, l'agent de réduction étant choisi parmi le formiate d'ammonium, l'acide formique et H2 gazeux,
et le catalyseur étant choisi parmi un catalyseur métallique hétérogène
le catalyseur métallique hétérogène étant un nanocatalyseur à base de Pd(0) qui est supporté de manière hétérogène sur de la silice contenant une matière choisie parmi un support de silice fonctionnalisée Pd(0)-amino.


 
2. Procédé selon la revendication 1, dans lequel le catalyseur est un catalyseur à base de Pd(0) est un support de silice fonctionnalisée Pd(0)-AmP choisi parmi un Pd(0)-AmP-MCF et un Pd(0)-AmP-CPG, de préférence le catalyseur à base de Pd est recyclable.
 
3. Procédé selon l'une quelconque des revendications précédentes, dans lequel les agents de réduction sont le formiate d'ammonium et le H2 gazeux, et dans lequel le solvant est de préférence du toluène.
 
4. Procédé selon l'une quelconque des revendications précédentes, dans lequel la réduction est effectuée à une température de 20 à 80 °C, de préférence à la température ambiante ou à 80 °C.
 
5. Procédé selon l'une quelconque des revendications précédentes, dans lequel l'alcool est converti en aldéhyde dans l'étape i), la conversion de l'alcool en aldéhyde étant réalisée en présence de NaOCl, de TEMPO (2,2,6,6-tétraméthylpipéridin-1-yl)oxyle), de NaOH, de KBr et d'O2.
 
6. Procédé selon l'une quelconque des revendications précédentes, dans lequel l'étape i) comprend les étapes :

a. d'addition d'une solution de KBr à une solution comprenant l'alcool et le TEMPO, de préférence, KBr est en solution aqueuse et le TEMPO est dans du CH2Cl2,

b. d'agitation du mélange, de préférence à 0 °C,

c. une solution de NaOCl est ajoutée au mélange réactionnel, de préférence, la solution de NaOCl a un pH de 9,

d. d'addition de NaOH au mélange réactionnel en présence d'O2, et

e. d'agitation du mélange, de préférence à 0 °C, et plus préférentiellement à 0 °C pendant 3 heures.


 
7. Procédé selon les revendications 1 à 5, dans lequel l'alcool est converti en cétone dans l'étape i), la conversion de l'alcool en cétone étant réalisée en présence d'O2, de TEMPO, de HNO3 et d'HCl.
 
8. Procédé selon l'une quelconque des revendications précédentes 1 à 6, dans lequel l'alcool est un diol, et dans lequel ledit diol est converti dans l'étape i) en aldol qui ensuite est soumis à une réaction de rétro-aldolisation catalytique spontanée pour donner les entités aldéhydes correspondantes, et dans lequel la liaison C=O des aldéhydes est ensuite ultérieurement réduite en une liaison C-H dans l'étape iii).
 
9. Procédé selon la revendication précédente, dans lequel le diol est choisi parmi la lignine et ses dérivés, de préférence, l'alcool est de la lignine contenant des alcools benzyliques, allyliques ou aliphatiques incluant des liaisons β-O-4 aryle éther, plus préférentiellement, la lignine est choisie parmi de la lignine de bois blanchie, de la lignine cellulolytique, de la lignine organosolv et de la lignine technique provenant de procédés de réduction en pâte.
 
10. Procédé selon la revendication précédente, comprenant les étapes de :

i. fourniture de lignine et d'oxydation de la lignine en un polymère comprenant des groupes aldéhydes,

ii. le polymère comprenant des groupes aldéhydes qui ont été fournis dans l'étape précédente subit ensuite une réaction de rétro-aldolisation catalytique spontanée qui mène à une dépolymérisation,

iii. réduction des groupes aldéhydes.


 
11. Procédé selon l'une quelconque des revendications précédentes 1 à 6, dans lequel l'alcool est un alcool primaire, et dans lequel l'alcool primaire est converti en aldéhyde dans l'étape i), et dans lequel la liaison C=O de l'aldéhyde est ensuite réduite en une liaison C-H.
 
12. Procédé selon l'une quelconque des revendications précédentes, dans lequel l'alcool est choisi parmi l'alcool vanillique, des alcools hydroxy-, méthoxy- et éthoxy-benzyliques, et dans lequel l'alcool vanillique, les alcools hydroxy-, méthoxy- et éthoxy-benzyliques sont convertis en leurs aldéhydes respectifs dans l'étape i), et dans lequel la liaison C=O de l'aldéhyde est ensuite réduite en une liaison C-H.
 
13. Procédé selon l'une quelconque des revendications précédentes 1 à 6, dans lequel l'alcool est un alcool secondaire, et dans lequel ledit alcool secondaire est converti en une cétone dans l'étape i), et dans lequel la liaison C=O de la cétone est ensuite réduite en une liaison C-H.
 






Cited references

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