WO2019199459A1

WO2019199459A1 - Preparation and use of biphenyl carboxylic acids, alcohols, and esters

Info

Publication number: WO2019199459A1
Application number: PCT/US2019/024303
Authority: WO
Inventors: Kapil KANDEL; Michael Salciccioli; Alex E. CARPENTER
Original assignee: ExxonMobil Chemical Patents Inc
Current assignee: ExxonMobil Chemical Patents Inc
Priority date: 2018-04-12
Filing date: 2019-03-27
Publication date: 2019-10-17
Anticipated expiration: 2020-10-12

Abstract

In a process for producing a biphenyl carboxylic acid, alcohol, and/or ester, benzene or toluene is reacted with a furanyl compound having the formula (I) where R1 is -H, -CH3, -CHO, -CH2OH, -COOH or -COOR2 and R2 is an alkyl group having from 1 to 20 carbon atoms in the presence of a first catalyst under conditions effective to produce a 2-R1, 5 -phenyl-substituted furan compound. The latter is then reacted with a dienophile under cycloaddition reaction conditions and in the presence of a second catalyst to produce a bicyclic ether and the bicyclic ether is dehydrated to a biphenyl compound.

Description

PREPARATION AND USE OF BIPHENYL CARBOXYLIC ACIDS.

ALCOHOLS. AND ESTERS

INVENTOR! S) : Kapil Kandel, Michael Salciccioli, and Alex E. Carpenter. CROSS-REFERENCE OF RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 62/656,388, filed April 12, 2018, the disclosure of which is incorporated herein by reference.

FIELD

[0002] This disclosure relates to the preparation and use of biphenyl carboxylic acids, alcohols, and esters.

BACKGROUND

[0003] Biphenyl carboxylic acids, alcohols, and esters are useful intermediates in the production of a variety of commercially valuable products, including polyesters and plasticizers for PVC and other polymer compositions. For example, biphenyl mono- and dicarboxylic acids can be converted to plasticizers by esterification with long chain alcohols. In addition, diphenyl dicarboxylic acids are potential precursors, either alone or as a modifier for polyethylene terephthalate (PET), in the production of polyester fibers, engineering plastics, liquid crystal polymers for electronic and mechanical devices, and films with high heat resistance and strength. The 4-monocarboxylic acid and the 4,4’-dicarboxylic acid isomers are the most desired due to the properties of the resulting products and hence have the broadest application.

[0004] As disclosed in US 9,580,572 and US 9,663,417, the entire disclosures of which are incorporated herein by reference in their entirety, biphenyl carboxylic acids can be prepared by oxidation of dimethylbiphenyl (DMBP) compounds, which in turn may be produced by hydroalkylation of toluene followed by dehydrogenation of the resulting (methylcyclohexyl)toluene (MCHT). However, the DMBP product comprises a mixture of all six DMBP isomers, namely 2,2’, 2,3’ 2,4’, 3,3’, 3,4’, and 4,4’ DMBP, in which the 3,4’ isomer is usually the most abundant and the 4,4’ isomer normally comprises less than 20% of the overall isomer mixture. Thus, to maximize the production of the preferred 4,4’ isomer, most of the product must be recycled to an isomerization reactor, which increases the cost and complexity of the process.

[0005] Alternative routes to DMBP compounds via benzene are described in US 9,085,669, in which the benzene is initially converted to biphenyl, either by oxidative coupling or by hydroalkylation to cyclohexyl benzene (CHB) followed by dehydrogenation of the CHB, and then the biphenyl is alkylated with methanol. Again, the alkylated product comprises a mixture of DMBP isomers, in which the 4,4’ isomer is a minor component.

[0006] There is, therefore, interest in developing alternative processes for producing biphenyl carboxylic acids, alcohols and esters, in which the concentration of the 4- and 4,4’- isomers is increased.

[0007] Recently, in 8 Energy Environ. Sci. 317 (2015), Corma et al. reported the synthesis of high quality alkyl naphthenic kerosene from 5-hydroxymethylfurfural (HMF) and toluene in two steps. The first step involved alkylation of toluene with HMF followed by hydrodeoxygenation of alkylated product. ITQ-2 was shown to perform best for the first step alkylation reaction yielding 98% alkylated product with high para-selectivity (o:p:m = 22:76:2).

[0008] In addition, a palladium-catalyzed regioselective oxidative arylation of furan-2- carbonyl compounds with simple arenes to 5-arylfuran-2-carbonyls is described by Seayad et al. in 2(8) ACS Catal. 1787-1791 (2012).

[0009] It is also known from, for example, US 9,302,971 that substituted furan compounds can be converted to terephthalic acid using a Diels Alder cycloaddition reaction with ethylene. In particular, the ‘971 patent discloses that 5-hydroxymethylfurfural (HMF) or 2,5-bis hydroxymethylfuran (BHMF) can be converted to a bicyclic ether which can then dehydrated to a 2,5 substituted phenyl which in turn can be oxidized to terephthalic acid.

SUMMARY

[0010] According to the present disclosure, it has now been found that biphenyl-4- carboxylic acid and biphenyl-4,4’ -dicarboxylic acid and their corresponding alcohols and esters can be formed by a process including (1) reaction of benzene and/or toluene with certain furanyl compounds, particularly 2-substituted furan compounds (2) followed by tandem Diels- Alder/dehydration reaction of the reaction product with a dienophile, particularly ethylene. Since furfural or 2-furaldehyde can be produced from renewable hemi-cellulose, this process provides an attractive route to these biphenyl compounds.

[0011] Thus in one aspect, the present disclosure resides in a process for producing a biphenyl carboxylic acid, alcohol, and/or ester, the process comprising:

(al) reacting benzene with a furanyl compound having the formula (I):

where R¹ is -H, -CH₃, -CHO, -CH₂OH, -COOH or -COOR² and R² is an alkyl group having from 1 to 20 carbon atoms, in the presence of a first catalyst under conditions effective to produce a compound having the formula (II):

(bl) reacting at least part of the compound of formula (II) with a dienophile of formula (III):

where each Rⁿ is independently selected from the group consisting of -R³, -H, -CH3, -CHO, - CH2OH, -COOH or -COOR³, R³ is an alkyl group having from 1 to 20 carbon atoms, and where each Rⁿ can be the same or different, under cycloaddition reaction conditions and in the presence of a second catalyst to produce a bicyclic ether; and

(cl) dehydrating the bicyclic ether from (bl) to produce a compound of formula

(IV):

[0012] In a further aspect, the present disclosure resides in a process for producing a biphenyl carboxylic acid, alcohol, and/or ester, the process comprising:

(a2) reacting toluene with a furanyl compound having the formula (I):

where R¹ is -H, -CH₃, -CHO, CH₂OH, -COOH or -COOR² and R² is an alkyl group having from 1 to 20 carbon atoms, in the presence of a first catalyst under conditions effective to produce a compound having the formula (V):

(b2) reacting at least part of the compound of formula (V) with a dienophile of formula (III):

(III) ,

(c2) dehydrating the bicyclic ether from (b2) to produce a compound of formula

(VI):

[0013] In another aspect, the present disclosure resides in a product composition comprising a mixture of the compound of formula (II) and the compound of formula (IV).

[0014] In yet another aspect, the present disclosure resides in a product composition comprising a mixture of the compound of formula (V) and the compound of formula (VI).

DETAILED DESCRIPTION

[0015] Described herein is a novel process for producing biphenyl-4-carboxylic acid, biphenyl-4,4’ -dicarboxylic acid, and their corresponding alcohols and esters. The process comprises initially reacting a feedstock comprising benzene and/or toluene with a furanyl compound, preferably a 2-substituted furan compound, having the formula (I):

where R¹ is -H, -CH₃, -CHO, -CH₂OH, -COOH or -COOR² and R² is an alkyl group having from 1 to 20 carbon atoms, in the presence of a first catalyst under conditions effective to produce a compound having the formula (II) when the feedstock comprises benzene:

and/or a compound having the formula (V) when the feedstock comprises toluene:

[0016] The compounds (II) and/or (V) are then reacted with a dienophile of formula (III):

(III) ,

where each Rⁿ is independently selected from the group consisting of -R³, -H, -CH3, -CHO, - CH2OH, -COOH or -COOR³, R³ is an alkyl group having from 1 to 20 carbon atoms, and where each Rⁿ can be the same or different, under cycloaddition reaction conditions and in the presence of a second catalyst to produce a bicyclic ether in a combined Diels-Alder addition and dehydration sequence to produce biphenyl compounds having the formula (IV) and/or (VI):

[0017] Compounds (IV) and (VI) can be recovered as the desired acid, alcohol, or ester, where R¹ is -COOH, -CH2OH or -COOR². Alternatively or additionally, compound (IV) may be oxidized to produce the desired compound, e.g. acid, where R¹ is -CH3, -CHO, or -CH2OH, or alkylated and then oxidized to produce the desired compound, e.g. acid, where R¹ is -H. Similarly, compound (VI) may be oxidized to produce the desired compound, e.g. acid, where R¹ is -H, -CH₃, -CHO, or -CH₂OH, or alkylated and then oxidized to produce the desired acid where R¹ is -H.

[0018] Preferably, the starting furanyl compound of formula (I) is, or is derived from, furfural and especially furfural produced from renewable sources, such as hemi-cellulose.

[0019] Often, the initial reaction between the benzene and/or toluene and the compound of formula (I) comprises oxidative coupling and the first catalyst comprises at least one metal or compound thereof from Groups 8 to 13 of the Periodic Table, such as at least one of palladium or a palladium compound, zinc or a zinc compound, or a mixture thereof. Suitable reaction conditions for such an oxidative coupling step are described in 2(8) ACS Catal. 1787-1791 (2012), the entire contents of which are incorporated herein by reference, and include a temperature from 30°C to 250°C, such as from 50°C to l50°C. The reaction may be conducted in the presence of an inorganic or organic oxidant. Preferred suitable oxidants include oxygen or an oxygen containing gas, preferably at an oxygen partial pressure up to 5500 kPa-a, as well as copper or silver based oxidants described in 2(8) ACS Catal, (above), e.g., AgOAc.

[0020] Alternatively, the initial reaction between the benzene and/or toluene and the compound of formula (I) comprises alkylation and the first catalyst comprises a bifunctional catalyst comprising a molecular sieve and at least one dehydrogenation metal.

[0021] Suitable molecular sieves for use in the bifunctional alkylation catalyst comprise

BEA, FAU, and MWW structure type molecular sieves and mixtures thereof. BEA structure type molecular sieves include zeolite beta, which is described in US 3,308,069 and Re. No. 28,341. FAU structure type molecular sieves include zeolite Y, ultrastable Y (USY which is described in US 3,293,192 and 3,449,070), dealuminized Y (Deal Y which is described in US 3,442,795 and zeolite UHP-Y which is described in US 4,401,556. MWW structure type molecular sieves include MCM-22 (described in US 4,954,325), PSH-3 (described in US 4,439,409), SSZ-25 (described in US 4,826,667), ERB-l (described in EP 0293032), ITQ-l (described in US 6,077,498), ITQ-2 (described in WO 97/17290), MCM-36 (described in US 5,250,277), MCM-49 (described in US 5,236,575), MCM-56 (described in US 5,362,697), and mixtures thereof.

[0022] Suitable dehydrogenation metals for use in the bifunctional alkylation catalyst comprise include palladium, ruthenium, nickel, zinc, tin, and cobalt, with palladium being particularly advantageous. Preferably, the amount of dehydrogenation metal present in the catalyst is between 0.05 and 10 wt %, such as between 0.1 and 5 wt%, of the catalyst.

[0023] Suitable conditions for the alkylation reaction comprise a temperature from 200°C to 600°C and a pressure from 1,400 kPa-a to 14,000 kPa-a, preferably such that the reaction mixture is predominantly (>50 wt%) in the liquid phase.

[0024] Irrespective of whether the process which is used to react the benzene and/or toluene with the compound of formula (I) is oxidative coupling or alkylation, the high reactivity of the alpha-hydrogen next to the furanic oxygen means that the reaction product will contain a large concentration, typically at least 50%, such as at least 80%, even up to 100%, of the desired furanyl derivative, namely the compound of formula (II) or (V), by weight of the total converted materials. Concentrations of the 2,3- and 2,4-furanyl derivatives are typically less than 20%, such as less than 10%, by weight of the total converted materials.

[0025] After optional removal of some or all of any unreacted species, such as the benzene, toluene and/or furanyl starting materials (e.g., 2-fumayl starting materials), at least part of the compound of formula (II) or (V) is then reacted with the dienophile of formula (III), preferably ethylene, over a second catalyst via a Diels-Alder addition reaction to produce a phenyl- substituted bicyclic ether. The Diels-Alder product is a low-concentration intermediate with unfavorable equilibrium and readily dehydrates in-situ to the biphenyl compound of formula (IV) or (VI) respectively. Often, the dienophile of formula (III) is symmetric, i.e., each Rⁿ in the dienophile of formula (III) and in the produced biphenyl compound of formula (IV) or (VI) are the same. A preferred symmetric dienophile is ethylene. Alternatively, the dienophile of formula (III) may be asymmetric, as shown in formula (Ilia):

(Ilia) ,

where R^p and R^q are independently selected from the group consisting of -R³, -H, -CH₃, -CHO, -CH₂OH, -COOH or -COOR³, where R³ is an alkyl group having from 1 to 20 carbon atoms, and where R^p and R^q are different. In such aspects, the compound of formula (IV) typically comprises one or more of the following compounds as shown in formulas (IVa)-(IVb):

[0026] Likewise, in such aspects, the compound of formula (VI) typically comprises one or more of the following compounds as shown in formulas (Vla)-(VIb):

.

[0027] In any embodiment, the overall addition/dehydration sequence starting from the compound of formula (II) can be summarized as follows:

For example, the overall addition/dehydration sequence starting from the compound of formula (II) and using ethylene as the dienophile can be summarized as follows:

[0028] Similarly, in any embodiment, the overall addition/dehydration sequence starting from the compound of formula (V) can be summarized as follows:

For example, the overall addition/dehydration sequence starting from the compound of formula (V) and using ethylene as the dienophile can be summarized as follows:

[0029] Apart from ethylene, other preferred dienophiles include propylene and methyl acrylate. Often, two or more dienophiles may be used. [0030] The Diels-Alder reaction is conducted in the presence of an acidic second catalyst, preferably with Lewis acidity. Often, the second catalyst comprises an acidic molecular sieve such as an aluminosilicate molecular sieve having a silica to alumina molar ratio less than 75, for example less than 50, such as less than 30. Suitable molecular sieves may comprise MFI, BEA, FAU, MOR, MTW, MFS, FER, CHA, and MWW structure type molecular sieves, and mixtures thereof. Additionally or alternatively, Brpnsted and/or Lewis acids can be used as the second catalyst. Suitable Brpnsted acid catalysts include acetic acid and its halogenated analogs, e.g., trifluoroacetic acid, trichloroacetic acid, hexachloroanbtimonate ( HSbCL), trifluoromethanesulfonic acid (HSO3CF3), and p-toluenesulfonic acid (HSO3T0S). Suitable Lewis acids include BX_3, AlX₃, RAIX2, R₂AlX, TiX₄, SnX₂, SnX₄, ZnX₂, SbX₃, SbX₅, ScX₃, where X is selected from F, Cl, Br, and where R is an alkyl group having from 1 to 22 carbon atoms. Additional suitable Lewis acids include, but are not limited to, Sc(OTf)3, lanthanide (III) species, Lewis acidic transition metal complexes, and Ti(OR⁴)₄, where R⁴ comprises an alkoxide or phenoxide group having from 1 to 22 carbon atoms.

[0031] Suitable conditions for the cycloaddition/dehydration reaction include a temperature from l00°C to 400°C and a pressure of 25 to 5000 psig (270 to 34600 kPa-a). In any embodiment, the rate of the Diels-Alder reaction may be enhanced by employing strategies described in Pindur et ah, Acceleration Selectivity Enhancement of Diels-Alder Reactions by “Special Catalytic Methods,” 93 Chem. Rev. 741-61 (1993), the entire contents of which are incorporated herein by reference.

[0032] Where the starting phenyl compound is benzene, the product of the cycloaddition/dehydration reaction will generally contain a mixture of the compound of formula (IV) together with some unreacted compound of formula (II), optionally together with unreacted dienophile, such as ethylene, and water by-product. The desired compound of formula (IV) can then be recovered by known separation methods, including distillation and phase separation. Preferably, water may be removed as the cycloaddition/dehydration reaction proceeds.

[0033] Similarly, where the starting phenyl compound is toluene, the product of the cycloaddition/dehydration reaction will generally contain a mixture of the compound of formula (VI) together with some unreacted compound of formula (V), together with unreacted dienophile, such as ethylene, and water by-product. The desired compound of formula (VI) can then be recovered by known separation methods, including distillation and phase separation. Preferably, water may be removed as the cycloaddition/dehydration reaction proceeds.

[0034] In some aspects, where R¹ in the starting furanyl compound (I) is -CHO, -CH2OH, -COOH or -COOR², it may be desirable to reduce compound (II) or (V) to the corresponding 2-methyl derivative prior to Diels-Alder/dehydration reaction to increase the rate of the reaction with the dienophile, such as ethylene. Such reduction can readily be effected using a supported Ni/Fe catalyst.

[0035] Compound (IV) can be oxidized to produce the desired compound, e.g. biphenyl-4- carboxylic acid, in aspects where R¹ in the starting furanyl compound (I) is -CH₃, -CHO, or - CH₂OH, or alkylated followed by oxidation produce the desired compound, e.g. biphenyl-4- carboxylic acid and/or biphenyl-4,4’ -carboxylic acid, where R¹ in the starting furanyl compound (I) is -H. Similarly, compound (VI) can be oxidized to the desired compound, e.g. biphenyl-4-carboxylic acid and/or biphenyl-4,4’-carboxylic acid, in aspects where R¹ in the starting furanyl compound (I) is -H, -CH₃, -CHO, or -CH₂OH, or alkylated followed by oxidation to the desired compound, e.g. biphenyl-4-carboxylic acid and/or biphenyl-4,4’ - carboxylic acid, where R¹ in the starting furanyl compound (I) is -H. Such oxidation and, optionally, alkylation may be conducted by methods well known in the art. For example, compound (IV) or compound (VI) may be oxidized by reaction with an oxidant, such as oxygen, ozone or air, or any other oxygen source, such as hydrogen peroxide, in the presence of a catalyst and with or without a promoter, such as Br, at temperatures from 30°C to 300°C, such as from 60°C to 200°C. Suitable catalysts comprise Co or Mn or a combination of both metals. The oxidation is normally conducted in solution, generally in acetic acid as solvent.

[0036] It will be appreciated that the compounds of formula (IV) and (VI), where R¹ is - COOH, can be converted to an ester by reaction with an alcohol. Similarly, the compounds of formula (IV) and (VI), where R¹ is -CH₂OH, can be esterified by reaction with a carboxylic acid.

[0037] While the present invention has been described and illustrated by reference to particular embodiments, those of ordinary skill in the art will appreciate that the invention lends itself to variations not necessarily illustrated herein. For this reason, then, reference should be made solely to the appended claims for purposes of determining the true scope of the present invention.

Claims

1. A process for producing a biphenyl carboxylic acid, alcohol, and/or ester, the process comprising:

(al) reacting benzene with a furanyl compound having the formula (I):

where R¹ is -H, -CH₃, -CHO, -CH₂OH, -COOH, or -COOR² and R² is an alkyl group having from 1 to 20 carbon atoms, in the presence of a first catalyst under conditions effective to produce a compound having the formula (II):

where each Rⁿ is independently selected from the group consisting of -R³, -H, -CH3, - CHO, -CH2OH, -COOH or -COOR³, R³ is an alkyl group having from 1 to 20 carbon atoms, and where each Rⁿ can be the same or different, under cycloaddition reaction conditions and in the presence of a second catalyst to produce a bicyclic ether; and (cl) dehydrating the bicyclic ether from (bl) to produce a compound of formula (IV):

2. The process of claim 1, wherein the reacting (al) comprises oxidative coupling and the first catalyst comprises at least one metal or compound thereof from Groups 8 to 13 of the Periodic Table.

3. The process of claim 2, wherein the first catalyst comprises at least one of palladium, zinc, or a compound thereof.

4. The process of claim 2 or 3, wherein the reacting (al) is conducted in the presence of an oxidant comprising oxygen or an oxygen-containing gas, and wherein the conditions in (al) include a temperature from 30°C to 250°C and an oxygen partial pressure of up to 5500 kPa-a.

5. The process of claim 1, wherein the reacting (al) comprises alkylation and the first catalyst comprises a bifunctional catalyst comprising a molecular sieve and at least one dehydrogenation metal.

6. The process of claim 5, wherein the molecular sieve comprises a molecular sieve of the MFI, BEA, MOR, FAU or MWW structure type or a mixture thereof.

7. The process of claim 5 or 6, wherein the conditions in (al) include a temperature from 200°C to 600°C.

8. The process of any one of claims 1 to 7, wherein the second catalyst comprises an acidic molecular sieve.

9. The process of any one of claims 1 to 8, wherein the second catalyst comprises a Brpnsted acid and/or a Lewis acid.

10. The process of any one of claims 1 to 9, wherein the cycloaddition reaction conditions include a temperature from l00°C to 400°C and/or a pressure of 25 to 5000 psig (270 to 34600 kPa-a).

11. The process of any one of claims 1 to 10, wherein the reacting (bl) and dehydrating (cl) are conducted in the same reaction zone in the presence of the second catalyst.

12. The process of any one of claims 1 to 11, wherein the dienophile is selected from the group consisting of ethylene, propylene, methyl acrylate, and mixtures or combinations thereof.

13. The process of any one of claims 1 to 12, wherein the furanyl compound having the formula (I) comprises 2-methylfuran or furfural and the process comprises the further step of oxidizing the compound of formula (IV) to produce biphenyl-4-carboxylic acid.

14. The process of any one of claims 1 to 12, wherein the furanyl compound having the formula (I) comprises furan and the process comprises the further steps of alkylating the compound of formula (IV) to produce an alkylated compound and oxidizing the alkylated compound to produce biphenyl-4-carboxylic acid and/or biphenyl-4,4’ - carboxylic acid.

15. A process for producing a biphenyl carboxylic acid, alcohol, and/or ester, the process comprising:

(a2) reacting toluene with a furanyl compound having the formula (I):

where each Rⁿ is independently selected from the group consisting of -R³, -H, -CH₃, - CHO, -CH₂OH, -COOH or -COOR³, R³ is an alkyl group having from 1 to 20 carbon atoms, and where each Rⁿ can be the same or different, under cycloaddition reaction conditions and in the presence of a second catalyst to produce a bicyclic ether; and (c2) dehydrating the bicyclic ether from (b2) to produce a compound of formula

(VI):

(VI).

16. The process of claim 15, wherein the reacting (a2) comprises oxidative coupling and the first catalyst comprises at least one metal or compound thereof from Groups 8 to 13 of the Periodic Table.

17. The process of claim 16, wherein the first catalyst comprises at least one of palladium, zinc or a compound thereof.

18. The process of 16 or 17, wherein the reacting (a2) is conducted in the presence of an oxidant comprising oxygen or an oxygen-containing gas, and wherein the conditions in (a2) include a temperature from 30°C to 250°C and an oxygen partial pressure of up to 5500 kPa-a.

19. The process of claim 15, wherein the reacting (a2) comprises alkylation and the first catalyst comprises a bifunctional catalyst comprising a molecular sieve and at least one dehydrogenation metal.

20. The process of claim 19, wherein the molecular sieve comprises a molecular sieve of the MFI, BEA, MOR, FAU or MWW structure type or a mixture thereof.

21. The process of claim 19 or 20, wherein the conditions in (a2) include a temperature from 200°C to 600°C.

22. The process of any one of claims 15 to 21, wherein the second catalyst comprises an acidic molecular sieve.

23. The process of any one of claims 15 to 22, wherein the second catalyst comprises a Brpnsted acid and/or a Lewis acid.

24. The process of any one of claims 15 to 23, wherein the cycloaddition reaction conditions include a temperature from l00°C to 400°C and/or a pressure of 25 to 5000 psig (270 to 34600 kPa-a).

25. The process of any one of claims 15 to 24, wherein the reacting (b2) and dehydrating (c2) are conducted in the same reaction zone in the presence of the second catalyst.

26. The process of any one of claims 15 to 25, wherein the dienophile is selected from the group consisting of ethylene, propylene, methyl acrylate, and mixtures or combinations thereof.

27. The process of any one of claims 15 to 26, wherein R¹ is -H, -CH₃, -CHO, CH₂OH, or -COOH and the process comprises the further step of oxidizing the compound of formula (VI) to produce biphenyl-4-carboxylic acid and/or biphenyl-4,4’-carboxylic acid.

28. The process of any one of claims 15 to 27, wherein R¹ is -H and the process comprises the further steps of alkylating the compound of formula (VI) to produce an alkylated compound and oxidizing the alkylated compound to produce biphenyl-4-carboxylic acid and/or biphenyl-4,4’ -carboxylic acid.

29. A product composition comprising a mixture including:

(a) a compound having the formula (II):

where R¹ is -H, -CH₃, -CHO, CH₂OH, -COOH or -COOR² and R² is an alkyl group having from 1 to 20 carbon atoms; and

(b) a compound of formula (IV):

where each Rⁿ is independently selected from the group consisting of -R³, -H, -CH3, - CHO, -CH2OH, -COOH or -COOR³, R³ is an alkyl group having from 1 to 20 carbon atoms, and where each Rⁿcan be the same or different.

30. A product composition comprising a mixture including:

(a) a compound having the formula (V):

(b) a compound of formula (VI):

(VI) ;

where each Rⁿ is independently selected from the group consisting of -R³, -H, -CH3, - CHO, -CH2OH, -COOH or -COOR³, R³ is an alkyl group having from 1 to 20 carbon atoms, and where each Rⁿ can be the same or different.