NO841860L - PROCEDURE FOR THE PREPARATION OF CARBOXYL ACID ESTERS AND / OR CARBOXYLIC ACIDS - Google Patents

Description

The present invention generally relates to a process

method for producing carboxylic acid esters and/or carboxylic acids and in particular a method for producing

lation of carboxylic acid esters and/or carboxylic acids by catalyzed reaction of an unsaturated hydrocarbon, carbon monoxide and either water or an alcohol, possibly in the vicinity of

be of oxygen.

Processes for the production of esters by reaction of

an olefin with carbon monoxide and an alcohol in the presence of a catalyst and in the presence or absence of oxygen is known. Representative of the published technique is the US patent

No. 4,303,589, Belgian Patent No. 877,770, Japanese Patent Publication No. 53040709 and US Patent No. 3,780,074.

US Patent No. 4,303,589 (Monsanto) describes a progress

method for the preparation of carboxylate esters by (a) reacting internal olefins with carbon monoxide and an alcohol at 170-200°C and 84.4-126.5 kg/cm<2> gauge pressure in the presence of a cobalt catalyst and a pyridine promoter,

(b) diluting the reaction mixture with a large amount of hydrocarbon to effect phase separation, (c) separating the ester from the second phase containing more than 90%

of the cobalt catalyst, and (d) recycling of catalys-

tor to step (a).

Belgian Patent No. 877,770 describes the preparation of polycarboxylic esters by reacting an olefin containing at least two conjugated double bonds with carbon monoxide and an alcohol in the presence of a base and a palladium/copper catalyst.

Japanese Patent Publication No. 53040709 describes the preparation of dicarboxylic acid diesters by reacting an olefin, carbon monoxide, oxygen and an alcohol in the presence of a catalyst containing (a) a palladium group metal or a compound thereof, (b) a copper salt

and (c) is tertiary amine.

Finally, US Patent No. 3,780,074 describes the preparation of alkadiene esters by reacting a C4-12 acyclic conjugated aliphatic diolefin with a ^1-20 raonohydroxy alcohol and carbon monoxide in the presence of 0-valence palladium and a phosphine activator at 80-160 °C in the absence of oxygen.

There are also known methods for the hydrophoreesterification of acetylene for the production of isomeric esters. E.g. reports G.P. Chiusli et al. in Chem. Ind., 977, (1968) reaction of acetylene with carbon monoxide in the presence of 4% oxygen and thiourea and a palladium (II) chloride catalyst.

A disadvantage of this process is that the selectivity of isomeric esters (cis- and trans-diesters) is significantly reduced.

characterized by the accompanying formation of polymeric materials and isomeric muconate esters.

It has now been found that carboxylic acid esters and/or carboxylic acids can be produced by reacting an unsaturated hydrocarbon with carbon monoxide and either water or an alcohol in the presence of a protonic acid and as catalyst (a) at least one of the metals palladium, rhodium, ruthenium, yuridium and cobalt, and (b) copper, both in the presence and absence of oxygen. In contrast to most of the previously known methods which use a base as an essential reactant, the present method uses an acid. The method according to the invention, in contrast to previously known processes, can be carried out under relatively mild conditions and exhibits a high regiospecificity for desired products.

Accordingly, according to a feature of the present invention, a method for the production of a carboxylic acid ester is provided and this method comprises the reaction of an unsaturated hydrocarbon with carbon monoxide and

an alcohol in the presence of a protonic acid and as catalysis-

tor (a) at least one of the metals palladium, rhodium, ruthenium, iridium and cobalt, and (b) copper.

The unsaturated hydrocarbon may conveniently be an olefin. The olefin can suitably be an acyclic olefin containing 2-30 carbon atoms per molecule or a cyclic olefin containing 5-30 carbon atoms per molecule. The olefin can either have one, two or three olefinic carbon-carbon double bonds per molecule, which double bonds may be internal or terminal and may be conjugated or non-conjugated in olefins containing multiple carbon-carbon double bonds. Suitable olefins can be represented by the general formula RCH = CHR''"where R

and R independently are either hydrogen, alkyl, alkenyl, alkadienyl, cycloalkyl, aryl, alkaryl, cycloalkenyl or cycloalkadienyl groups, or R and R"" together form a cyclic system. Examples of suitable mono-olefins include propylene, 1-butene , 2-butene, 1-pentene, 2-pentene, 1-hexene, 2-hexene, 3-hexene, 1-octene, 1-decene, cyclododecene, 2-methyl-l-undecene, styrene, 4-methylstyrene, 4 -isopropylstyrene and the like. Examples of suitable diolefins include 1,3-butadiene, 1,3-pentadiene, 1,5-hexadiene, 4-vinylcyclohexene, 1,7-octadiene, 1,9-decadiene and the like. Alternatively, diolefins can be allene or an allene homolog, e.g., dimethylallene. Examples of suitable triolefins include 1,5,9-cyclododecatriene, cycloheptatriene, and the like. Mixtures of olefins may also be used. Terminal mono-olefins react to form esters with branched chain Internal mono-olefins, eg 2-decene and 4-methyl-2-pentene, react exclusively at the 2-position, the cis isomer being more reactive than tran the s-isomer.

Alternatively, the unsaturated hydrocarbon may be an alkyne. The alkyne can be either a terminal or internal alkyl. Suitable terminal alkynes include acetylene, 1-pentyne, 1-hexyne, 1-octyne, benzylacetylene, cyclohexylacetylene and 3-methyl-1-pentyne. Suitable internal alkynes include 2-heptyne, 2-nonyne, 4-methyl-2-pentyne and 2,9-dimethyl-5-desyne. Typically, when using acetylene as the unsaturated hydrocarbon, the product comprises mainly dimethyl maleate together with a minor proportion of dimethyl fumarate. Generally, terminal alkynes give the cis-diester as the main product and the trans-diester as a by-product. Internal alkynes give on

on the other hand, usually monoesters, not diesters, and further, the monoesters tend to have cis-stereochemistry.

The carbon monoxide can be provided by any suitable source. The carbon monoxide pressure can conveniently be the autogenous pressure at the reaction temperature used. Alternatively, elevated pressures, suitably in the range of 0.14-17.6 kg/cm<2> manometer pressure above the autogenous pressure at the reaction temperature, can be used,

With regard to the alcohol reactant, monohydric and polyhydric alcohols can be used. Suitable alcohols can be represented by the formula R^CHOH where R is independently hydrogen, alkyl, aryl or hydroxyalkyl, or the two R groups together form a ring. The alcohol is conveniently an alkanol. Examples of suitable alcohols include methanol, ethanol, propanols, butanols, pentanols, hexanols, e.g. 2-ethylhexanol, benzyl alcohol and 1,4-butadiol. The amount of alcohol used can conveniently be at least the stoichiometric amount required to react with the unsaturated hydrocarbon. However, it is preferred to use a significant excess of alcohol above the stoichiometric amount in the spoon, as the alcohol then represents the double role of being reactant and diluent for the reaction.

The protonic acid can either be a mineral acid, preferably hydrochloric or sulfuric acid, or an organic acid which can conveniently be a carboxylic acid•

With regard to the catalyst, one or more of the metals palladium, rhodium, ruthenium, iridium and cobalt are used as component (a). The metal(s) may be in the form of the elemental metal(s), such as a finely divided powder, or in the form of a compound of the metal(s). Suitable compounds of the metal(s) include the chlorides, iodides, acetates and nitrates, preferably the chlorides. The metal is preferably palladium, suitably in the form of palladium (II) chloride.

Copper, which constitutes component (b) in the catalyst, can suitably be added as a cupro- or cupri-compound or as a mixture thereof. A number of different copper compounds can be used in the present method. Examples of suitable copper compounds include copper (I) acetate, copper (II) acetylacetonate, copper (I) bromide, copper (I) chloride, copper (II) chloride, copper (I) iodide, copper (II) nitrate and the like.

With respect to the ratios of the catalyst components, the molar ratio of copper component (b) to metal component (a) can suitably be in the range from 1:1 to 200:1, preferably from 2:1 to 50:1.

The molar ratio of unsaturated hydrocarbon to metal compo-

ten (a) can suitably be in the range from 5:1

to 1000:1, preferably from 10:1 to 250:1.

Oxygen may or may not be present. However, it is preferred to operate in the presence of oxygen,

because by doing this, the product yield can be improved. Oxygen is added to the reaction either as essential

equal to pure oxygen or mixed with other gases such as

are essentially inert under the reaction conditions. Air can be suitably used as an oxygen source. The oxygen pressure can conveniently be the autogenous pressure at the reaction temperature used. Alternatively, elevated pressures can be used if this is desirable.

An additional solvent can be used if desired. The particular solvent used can form a single phase with the alcohol reactant. Alternatively, a solvent can be used which can form another liquid phase. The particular solvent used,

should be inert under the reaction conditions. Suitable solvents which form a single phase with the alcohol reactant include oxygenated hydrocarbons, e.g. tetrahydrofuran. Suitable solvents which can form a second liquid phase include aliphatic hydrocarbons, cycloaliphatic hydrocarbons, aromatic hydrocarbons, alkyl-substituted aromatic hydrocarbons or halogenated aliphatic or aromatic hydrocarbons. Examples of suitable solvents that can form a

other liquid phase includes benzene, toluene, hexane, cyclohexane, chlorobenzene, bromobenzene, a xylene, dichloromethane, chloroform and 1,2-dichloroethane. It will be understood by those skilled in the art that the organic solvent should be selected taking into account the difference in boiling points between the reaction products and the solvent portion in order to facilitate separation of the reaction mixture into its individual components. The amount of supplementary solvent based on the olef inreactant can vary over a wide range, suitably from 20 to 0.2, preferably from 5 to 1, parts by volume of supplementary solvent per volume fraction ole f inreactant.

If, in a modification of the invention, the alcohol reactant is replaced with water, provided that the amount of water is less than 8 molar equivalents based on the unsaturated hydrocarbon reactant and a solvent other than an alcohol is used, then instead of carboxylic acid ester the corresponding carboxylic acid will be formed.

The amount of water used is preferably less than 5, even more preferably approx. 1 molar equivalent based on the unsaturated hydrocarbon reactant.

Any suitable solvent other than an alcohol may be employed. Suitable solvents include ethers and hydrocarbons, e.g. paraffinic and aromatic hydrocarbons. The solvent is preferably an ether. Examples of suitable ethers include tetrahydrofuran, dioxane, glyme and crown ethers, of which tetrahydrofuran is preferred.

The method can conveniently be carried out at ambient temperature, although elevated temperatures, e.g. in the range 20-150oC or even higher, can be used. The reaction time can vary over a wide range, suitably from approx. 30 min. to 8 hours, although longer reaction times can be used if desired.

The method can be carried out batchwise or continuously, preferably continuously.

The invention will now be described in greater detail with reference to the following examples:

Process carried out 1 presence of oxygen

Example 1

Palladium (II) chloride (0.1 g 0.56 mmol) was added to methanol (50 mL) through which carbon monoxide (1 atmosphere) was bubbled. After 1 min. became conc. hydrochloric acid (0.5 ml) added. When the solution turned yellow (indicating that the palladium chloride had dissolved), copper (II) chloride (0.5 g, 3.7 mmol) was added, and oxygen (1 atmosphere) was bubbled through the solution in addition to the carbon monoxide. 1-Decene (6 mmol) was then added and the reaction mixture was stirred for 4 hours at 25°C. After two hours, a further 0.5 ml of conc. hydrochloric acid added.

The reaction product was then extracted with hexane and the hexane evaporated to give a pure product which was identified as methyl 2-methyldecanoate. The ester was obtained in 100% yield based on olefin reactant.

Example 2

Example 1 was repeated with the exception that 1-decene was replaced by 1,7-octadiene.

Example 3

Example 1 was repeated with the exception that 1-decene was replaced by 1,9-decadiene, and the reaction time was reduced to 3 hours.

Example 4

Example 1 was repeated with the exception that 1-decene was replaced by cyclododecene.

Example 5

Example 1 was repeated with the exception that 1-decene was replaced by propene.

Example 6

Example 1 was repeated with the exception that 1-decene was replaced by 2-methyl-1-undecene, and the product was separated by distillation after extraction with hexane.

Example 7

Example 6 was repeated with the exception that 2-methyl-1-undesene was replaced by 4-methyl-styrene.

The results from Examples 2-7 together with those from Example 1 are given in Table 1.

Example 8

Example 1 was repeated with the exception that conc. hydrochloric acid was replaced by conc. sulfuric acid (0.33 g).

Methyl 2-methyldecanoate was obtained in a yield of 92%.

Example 9

The procedure in Example 1 was repeated with the exception that 1,4-butanediol (0.7 g) was used instead of methanol, and tetrahydrofuran (30 ml) was used as a supplementary solvent. The amounts of other reactants were as follows:

palladium (II) chloride = 0.7 mmol

copper (II) chloride = 6 mmol

conc. hydrochloric acid = 0.1 ml

1-decene = 1.09 g

Carbon monoxide/oxygen was bubbled through mixture 1 for 16 hours.

After distillation of the crude product, the pure monoester was obtained

with the formula

achieved in a yield of 50%.

Example 10

Pallium (II) chloride (0.1 g, 0.56 mmol) was added to methanol (50 mL), through which carbon monoxide (1 atmosphere) was bubbled. After one minute, conc. hydrochloric acid (0.5 ml) added. When the solution had turned yellow (indicating that the palladium chloride had dissolved), copper (II) chloride (0.5 g, 3.7 mmol) was added, and oxygen (1 atmosphere) was bubbled through the solution in addition to the carbon monoxide. Acetylene (6 mmol) was then bubbled through the solution for 4 hours at 25°C. After two hours, a further 0.5 ml of conc. hydrochloric acid added.

The reaction product was then extracted with hexane and the hexane evaporated. Analysis of the product gave dimethyl maleate (86% yield) and dimethyl fumarate (14% yield).

Example 11

The procedure in Example 1 was repeated with the exception that acetylene was replaced by 1-pentyne. Cis- and trans-C3H7C(CO0CH3)=CHC00CH3 were obtained in yields of 72 and 25%, respectively.

Example 12

The procedure in example 1 was repeated with the exception of

that acetylene was replaced by 1-hexyne. Cis- and trans-C4H9C(COOCH3)=CHCOOC<H>3 were obtained in yields of 76 and 24%, respectively.

Example 13

FThe procedure in example 10 was repeated with an exception

of acetylene being replaced by 1-octyne. Cis- and trans-<C>6<H>13C(C00CH3)=CHC00CH3 were obtained in yields of 80 and

20%, respectively.

Example 14

The procedure in example 10 was repeated with an exception

for acetylene to be replaced by benzylacetylene• Cis- and trans- PhCH2CH2<C>(C00CH3)=CHC00CH3 were obtained in yields of

74 and 26%, respectively.

Example 15

The procedure in example 10 was repeated with an exception

for acetylene to be replaced by cyclohexylacetylene.

Cis- and trans- ^ C(COOCH3)=CHC00CH3 were obtained in yields of 85 and respectively.

Example 16

The procedure in example 10 was repeated with an exception

for acetylene to be replaced by 3-methyl-1-pentyne. Cis-

and trans-C2<H>5<C>H(CH3)C(COOCH3)<=>CHC00CH3 were obtained in yields of 84 and 16%, respectively.

Example 17

The procedure in example 10 was repeated with an exception

for acetylene to be replaced by 2-heptyne. C<H>3(CH2)3CH=C(CH3)C00CH3 and an ether was obtained in yield

of 90 and 10% respectively.

Example 18

The procedure in example 10 was repeated with an exception

of acetylene being replaced by 2-nonyne.

C<H>3(CH2)5CH=C(CH3)CO0CH3 and an ether were obtained in a ratio of 60 and 40% yield, respectively.

Example 19

The procedure in example 10 was repeated with an exception

for acetylene to be replaced by 4-methyl-2-pentyne (CH3)2CHCH=C(CH3)C00CH3 and an ether was obtained in yields of 75 and 25%, respectively.

Example 20

The procedure in example 10 was repeated with an exception

for acetylene to be replaced by 2,9-dimethyl-5-decene.

Cis-(CH3)2CHCH2CH2CH=C(CH2<C>H2CH(CH3)2COOCH3 and an ether were obtained in yields of 70 and 30%, respectively.

Example 21

Example 15 was repeated with the exception that methanol was replaced by ethanol, cis- and trans-

<C>6<H>11C(C00C2H5)=CHC00C2H5 was obtained in a yield of 86 and

13%, respectively.

Example 22

Example 17 was repeated with the exception that n-propyl alcohol was used instead of methanol.

Cis-CH3(CH2)3CH=C(CH3)C00<C>3<H>7 was obtained in a yield of

76%.

In examples 10-22, the percentage dividends are based

on alkyne reactant•

Example 23

Carbon monoxide was bubbled through a solution containing tetrahydrofuran (30 mL) and water (1 mL). Palladium (II) chloride (0.140 g, 0.78 mmol) was added, followed by conc. hydrochloric acid (1.0 ml), copper (II) chloride (0.84 g,

6.24 mmol), and then oxygen was bubbled through the mixture

the thing. 1-Decene (7.8 mmol) was added and the reaction mixture was stirred at room temperature for 4 hours.

The product was worked up by adding distilled water (50 ml) and extracting three times with hexane (250 ml in total). Extracts were dried using magnesium sulfate and then concentrated. Further purification was accomplished by dissolving the acid in 1M NaOH, extracting with ether, acidifying, and extracting again with ether.

2-Methyldecanoic acid was obtained in 100% yield.

Example 24

The procedure in example 23 was repeated with the exception that 1-benzene was replaced by 1-octene, and the reaction time was increased to 18 hours.

2-Methyloctanoic acid was obtained in 92% yield.

Example 25

The procedure in example 23 was repeated with the exception that 1-decene was replaced with vinylcyclohexene.

C6<H>11CH(C<H>3)COOH was obtained in 53% yield.

Example 2 6

The procedure in example 25 was repeated with the exception that the reaction time was increased to 18 hours.

C6H11CH(CH3)COOH was obtained in 89% yield.

Example 27

The procedure in example 23 was repeated with the exception that 1-decene was replaced by 1,7-octadiene, and the reaction time was increased to 18 hours.

HOCOCH(CH3)(CH2)4CH(CH3)COOH was obtained in 93% yield.

Example 28

The procedure in example 23 was repeated with the exception that 1-decene was replaced by 1,9-decadiene, and the reaction time was increased to 18 hours.

HOCOCH(CH3)(CH2)6CH(CH3)COOH was obtained in 100% yield.

Example 29

The procedure in example 23 was repeated with the exception that 1-decene was replaced by cis-2-decene.

C<H>3(CH2)7CH(CH3)COOH was obtained in 59% yield.

Example 30

The procedure in Example 23 was repeated with the exception that 1-decene was replaced with trans-2-decene.

C<H>3(CH2)7CH(C<H>3)COOH was obtained in 30% yield.

Example 31

The procedure in example 30 was repeated with an exception

so that the time was increased to 18 hours.

C<H>3(CH2)7CH(CH3)COOH was obtained in 77% yield.

Example 32

The procedure in example 23 was repeated with an exception

because cyclododecene was used instead of 1-decene. Yield of cyclododecane carboxylic acid was 64%.

Example 33

The procedure in example 23 was repeated with an exception

because cis-4-methyl-2-pentene was used instead of 1-decene. The yield of 2,4-dimethylpentanoic acid was 84%.

Example 34

The procedure in Example 23 was repeated with an exception

because trans-4-methyl 1-2-pentene was used instead of 1-decene. Yield of 2,4-dimethylpentanoic acid was 64%.

Example 35

The procedure in example 23 was used with the exception that instead of 1-decene, 1,7-octadiene (1.15 ml,

7.8 mmol) used. The amounts of the other reactants were as follows:

Tetrahydrofuran = 30 ml

Palladium (II) chloride = 0.130 g (0.7 mmol) Conc. hydrochloric acid = 0.1 ml

Copper (II) chloride = 6 mmol.

Water = 0.14 ml (7.8 mmol)

Carbon monoxide/oxygen was bubbled through the mixture for 16 hours.

An 80% mixture of monoacids with the formula

CH3CH(COOH)(CH2)4CH=CH2

and

CH 3 CH(COOH)(CH 2 ) 3 CH=CH 2 CH 3

was achieved.

Procedure carried out in the absence of oxygen

Example 36

Palladium (II) chloride (0.1 g, 0.56 mmol) was added to methanol (50 mL) through which carbon monoxide (1 atmosphere) was bubbled. Then the lm was conc. hydrochloric acid (1.0 ml) added. The solution turned yellow. 1-Decene (6 mmol) was added and the reaction mixture was stirred at room temperature. When the reaction mixture turned green, a small amount of copper (II) chloride was added (1:1 total ratio of palladium (II) chloride to copper (II) chloride). This operation was repeated until the solution turned green. Finally, the solution remained yellow, at which point it was extracted with hexane. The hexane was then evaporated to give methyl 2-methyl decanoate in 100% yield.

Example 37

Example 36 was repeated with the exception that 1-decene was replaced by 1-pentene.

Example 38

Example 36 was repeated with the exception that 1-decene was replaced by 2-methyl-1-undecene, and the product was separated by distillation after extraction with hexane.

Example 39

Example 36 was repeated with the exception that 1-decene was replaced by 4-methylstyrene, and the product was separated by desilation after extraction with hexane.

The results of Examples 36-39 together with those of Example 36 are set forth in Table 2.

In Examples 23-39, the percentage yields are based on olefin reactant.

Claims (10)

1. Process for the production of a carboxylic acid ester, characterized by reacting an unsaturated hydrocarbon with carbon monoxide and an alcohol in the presence of a protonic acid and as catalyst (a) at least one of the metals palladium, rhodium, ruthenium, iridium and cobalt, and (b) copper. 2. Method according to claim 1, characterized in that the unsaturated hydrocarbon is an olefin. 3. Method according to claim 1, characterized in that the unsaturated hydrocarbon is an alkyne. 4. Method any of the preceding claims, characterized in that the alcohol has the formula I^CHOH where R is independently hydrogen, alkyl, aryl or hydroxyalkyl, or the two R groups together form a ring. 5. Method according to any one of the preceding claims, characterized in that the protonic acid is either hydrochloric acid or sulfuric acid. 6. Method according to any one of the preceding claims, characterized in that component (a) in the catalyst is palladium. 7. Method according to any one of the preceding claims, characterized in that a supplementary solvent is used. 8. Modification of the method according to any one of the preceding claims, characterized in that the unsaturated hydrocarbon is reacted with carbon monoxide and water, provided that the amount of water is less than 8 molar equivalents based on the unsaturated hydrocarbon, in the presence of a solvent other than an alcohol, and the product thereby produced is a carboxylic acid. 9.. Method according to claim 8, characterized in that the solvent is an ether. 10. Method according to claim 9, characterized in that the ether is tetrahydrofuran.