BACKGROUND Processes for producing aromatic substituted aliphatic acids and their derivatives via palladium catalyzed carbonylation reactions are of great interest. Several palladium catalyzed processes for producing aromatic substituted aliphatic acids from olefins have been described, including those disclosed in GB 1 565 235 (1980), U. S. 5,315,026 (1994), U. S. 5,315,028 (1994), U. S. 5,482,596 (1996), U. S. 5,536,870 (1996), and WO 98/30529 (1998). Another convenient route to aromatic substituted aliphatic acids and their derivatives is a palladium catalyzed carbonylation utilizing aromatic substituted alcohols or aromatic substituted alkyl halides. Such processes have been the subject of previous studies, including those reported in JP Kokoku 56-35659 (1981), JP Kokai 59-95238 (1984), JP Kokai 59-95239 (1984), E. P. 338852A1 (1989), U. S. 4,981,995 (1991), and U. S. 5,322,959 (1994).

Two possible isomers may result from the palladium catalyzed carbonylation reaction, one in which the carboxyl group is bound to the alpha carbon, and one in which the carboxyl group is bound to the beta carbon. When the desired carbonylation product is one isomer, formation of mixtures containing both isomers becomes a problem because they are difficult to separate.

THE INVENTION The processes provided by this invention convert aromatic substituted alcohols and/or aromatic substituted alkyl halides to carboxylic acids and their derivatives, including esters, salts, racemates, and individual optical isomers. In the processes described herein, formation of the beta-substituted isomer is reduced, such that the product is essentially pure after the initial reaction workup. This exceptionally high reaction regioselectivity is brought about by use as the carbonylation catalyst of a palladium catalyst comprising a cycloalkyldiarylphosphine ligand.

Accordingly, an embodiment of this invention entails forming a mixture from ingredients comprising (i) an aromatic substituted alcohol and/or an aromatic substituted alkyl halide, (ii) a copper-free palladium catalyst comprising a palladium compound in which palladium has a valence of zero to two and a phosphine ligand wherein the ligand is a cycloalkyldiarylphosphine, and (iii) an optional halogen acid. The mixture is heated with CO at a pressure of at least about 1 atmosphere and a temperature from 25 °C to 300°C to form an aromatic substituted aliphatic acid or ester. In other words, this embodiment comprises carbonylating with carbon monoxide a mixture formed from an aromatic substituted alcohol and/or an aromatic substituted alkyl halide, and a palladium catalyst comprising a palladium compound in which palladium has a valence of zero to two and a phosphine ligand wherein the ligand is a cycloalkyldiarylphosphine, optionally with a halogen acid such as aqueous hydrochloric acid or aqueous hydrobromic acid. When an aromatic substituted alcohol is used, the halogen acid is necessary, and at least a major portion of the aromatic substituted alcohol is rapidly converted in situ into an aromatic substituted alkyl halide by reaction with the halogen acid. The resultant aromatic substituted alkyl halide is then carbonylated. The product of the reaction is a carboxylic ester or a mixture of a carboxylic acid and its ester when an alcohol is incorporated in the reaction; the ester can be hydrolyzed to give the desired carboxylic acid.

A feature of this invention is that the palladium catalyst used is either a single component (i. e., a cycloalkyldiarylphosphine-ligated palladium compound), or is a composition made from two components, viz. (a) one or a mixture of palladium compounds with a valence from zero to two and (b) cycloalkyldiarylphosphine ligand. The catalyst is thus copper-free. Further, when conducted under aqueous conditions, the product of the reaction is a carboxylic acid, which thus can be produced directly in the process when the desired product is a high purity, alpha-substituted carboxylic acid. In short, the acid can be produced directly without need for further reactions.

Another feature of this invention is that it makes possible the formation of the alpha- substituted isomer in extremely high yields, even though the amount of catalyst can be, and preferably is, extremely small. For example, it is possible to achieve yields of the alpha- substituted isomer of at least about ninety percent in reactions periods of six hours or less, using the foregoing palladium catalyst in amounts corresponding to a ratio of 0.01 mole of palladium compound per mole of aromatic substituted alcohol and/or aromatic substituted halide, or less. Moreover, this invention makes it possible to obtain the product with very

high ratios of the alpha-substituted isomer, generally with ratios of alpha to beta isomer of at least 100: 1, and, in preferred cases, in ratios of 500: 1, or more.

The aromatic substituted alcohols and/or aromatic substituted halides in this invention are alkyl halides and alcohols substituted with an aromatic group; preferably, the aromatic group is bound to the 1-position of the alcohol. Typically these compounds have a general formula (I), in which X is a halogen atom or preferably a hydroxy group. When X is a halogen atom, it is an iodine, a bromine, or most preferably, a chlorine atom. The carboxylic compounds produced by the practice of this invention have the formula (II).

In both formula (I) and formula (II), R'and RI are the same or different and are selected from hydrogen atoms, hydrocarbyl groups, functionally-substituted hydrocarbyl groups, substituted or unsubstituted aryl groups, and halogen atoms. Examples include compounds of formula (I) wherein R'and R'are hydrogen atoms, substituted or unsubstituted phenyl, Cl to C6 alkyl, and/or trifluoromethyl. The preferred compounds of formula (I) are those in which R'and R'are hydrogen atoms and/or C, to C6 alkyl groups. Compounds in which R'is a hydrogen atom are more preferred; compounds in which R'is a hydrogen atom and R2 is a C, to C6 alkyl group are highly preferred. The preferred alkyl halide moiety is ethyl halide, and the preferred alcohol moiety is ethanol, which requires in formula (I) that R' is a hydrogen atom and R2 is a methyl group in the most highly preferred compounds.

Aromatic substituted alcohols are the preferred starting materials for the carbonylation reaction.

In formula (II), Z is an alkali metal atom (preferably Na or K) when the acid is neutralized with a suitable base such as NaOH or KOH, a hydrocarbyl group (preferably C,-C6 alkyl), a functionally-substituted hydrocarbyl group, or, most preferably, a hydrogen atom. By suitable modifications of or additions to the procedures described herein, compounds of formula (II) can be produced in which Z can be any of a wide variety of other groups, non-limiting exemplifications of which include ammonium, quaternary ammonium, one-half equivalent of a divalent metal atom, one-third equivalent of a trivalent

metal cation, and so forth.

The aromatic group [Ar of formula (I) and formula (II)] is aryl, substituted aryl, heteroaryl, substituted heteroaryl, aralkyl, or substituted aralkyl, encompassing phenyl, naphthyl, biphenyl, carbazolyl, or substituted phenyl, naphthyl, biphenyl, or carbazolyl, with at least one substituent which may be benzoyl, naphthoyl, halogen, amino, nitro, hydroxy, alkyl, or alkoxy; the preferred aromatic group depends on the product desired.

Examples of substituted aryl groups include isobutylphenyl, methoxynaphthyl, phenoxyphenyl, fluorobiphenylyl, benzoylphenyl, and chlorocarbazolyl.

In highly preferred embodiments, the aromatic substituted alcohols and/or aromatic substituted alkyl halides of choice are 1- (4-isobutylphenyl) ethanol or 1- (4- isobutylphenyl) ethyl chloride, 1- (3-fluoro-4-biphenylyl) ethanol or 1- (3-fluoro-4- biphenylyl) ethyl bromide, 1- (6-methoxy-2-naphthyl) ethanol or 1- (6-methoxy-2- naphthyl) ethyl chloride, 1- (3-phenoxyphenyl) ethanol or 1- (3-phenoxyphenyl) ethyl bromide, 1- (3-benzoylphenyl) ethanol or 1- (3-benzoylphenyl) ethyl chloride, and 1- (6-chloro-2- carbazolyl) ethyl bromide or 1- (6-chloro-2-carbazolyl) ethanol which yield, respectively, ibuprofen, 2- (4-isobutylphenyl) propionic acid (U. S. Pat. Nos. 3,228,831 and 3,385,886); 2- (3-fluoro-4-biphenylyl)-propionic acid (also known as flurbiprofen) (U. S. Pat. No.

3,755,427); racemic 2- (6-methoxy-2-naphthyl) propionic acid which can be resolved to d-2- (6-methoxy-2-naphthyl) propionic acid (also known as naproxen) (U. S. Pat. No. 3,637,767); a-dl-2- (3-phenoxyphenyl) propionic acid (also known as fenoprofen) (U. S. Pat. No.

3,600,437); 2- (3-benzoylphenyl) propionic acid (also known as ketoprofen) (U. S. Pat. No.

3,641,127); and 2- (6-chloro-2-9H-carbazolyl) propionic acid (also known as carprofen) (U. S.

3,896,145 and U. S. 4,158,007).

The present invention embraces the formation of any racemates and individual optical isomers of the compounds of formula (II) having a chiral carbon atom. For example, when compounds of formula (II) wherein the acid is 2- (6-methoxy-2- naphthyl) propionic acid, are subjected to resolution as taught in U. S. Patent 4,246,164 (incorporated herein by reference), the analgesic compound naproxen is produced.

The palladium catalyst can be (1) a palladium catalyst generated in situ from a mixture of one or more palladium compounds having a valence of zero to two and a cycloalkyldiarylphosphine ligand of the following formula (III), or (2) a preformed ligated palladium catalyst in which the palladium has a valence of zero to two and the ligand has formula (III).

In formula (III), R'and R"are the same or different and are individually hydrogen, alkyl, aryl or substituted aryl; Ar is phenyl, naphthyl, substituted phenyl or substituted naphthyl; and n is an integer from 3 to 6. Preferably, R'and R"are the same or different and are Cl to C6 alkyl, Ar is phenyl or naphthyl, and n is 3 or 4. Most preferably, R'is methyl or ethyl, R"is C3 to C6 branched alkyl, Ar is phenyl, and n is 4. Especially preferred as the phosphine ligand is neomenthyldiphenylphosphine.

Active catalytic species are preferably formed in situ by the addition to the reaction mixture of the individual components. One or more palladium compounds and the cycloalkyldiarylphosphine ligand can be added to or included in the reaction vessel separately from each other. In such a case, the palladium compound (s) and the cycloalkyldiarylphosphine ligand can be introduced into the reaction vessel concurrently or sequentially in any order. However, the catalyst can be preformed externally to the reaction mixture and charged to the reactor as a preformed catalyst composition.

The use of salts of palladium in forming the catalysts is preferable because catalyst compositions formed from palladium salts appear to have greater activity than those made from palladium metal itself. Inorganic salts may be the palladium salts, and include the chlorides, bromides, nitrates, and sulfates. Organic palladium salts may also be used, and include complexes and salts such as the carboxylates. Examples of palladium compounds include PdCl2, Pd (OAc) 2, Pd (CH3CN) 2CI2, PdBr2, Pd (NH3) 2CI2, Pd (CH3CN) 4 (BF4) 2, tris (dibenzylideneacetone) dipalladium (0) chloroform adduct, and bis (dibenzylideneacetone) palladium (0). Of the salts, Pd (II) halides (chloride, bromide, iodide) and Pd (II) carboxylates (e. g., acetate or propionate) are most preferred. Thus, for example, palladium (II) chloride or palladium (II) acetate and might be used in the carboxylation; in the most preferred case, PdCI, and neomenthyldiphenylphosphine are in fact used. Examples of preformed ligated palladium catalysts include tetrakis (neomenthyldiphenylphosphine) palladium (0), tetrakis (neomenthyldiphenylphosphine)- palladium (II) perchlorate, bis (neomenthyldiphenylphosphine) palladium (II) chloride, and bis (neomenthyldiphenylphosphine) palladium (II) acetate.

Mixing one or more palladium compounds and cycloalkyldiarylphosphine ligand forms a catalyst. The molar ratio of cycloalkyldiarylphosphine ligand to palladium compound ranges from at least 1: 1 to 20: 1; preferred ratios range from 2: 1 to 15: 1. While it is possible to carry out the reaction using a mole ratio of aromatic substituted alcohol and/or aromatic substituted alkyl halide to palladium compound in the range of 25: 1 to 50: 1, it is distinctly preferred to employ molar ratios of aromatic substituted alcohol and/or aromatic substituted alkyl halide to palladium compound of at least 100: 1, and more preferably at least to 500: 1. Typically, this ratio can be as high as 10000: 1, but preferably, the ratio does not exceed 5000: 1. Highly preferred as a carbonylation catalyst is the species formed in situ from the mixture of Pd (II) and/or Pd (0) compound (s) and neomenthyldiphenylphosphine. The use of an aromatic substituted alcohol with the catalyst species formed from the mixture of a Pd (II) salt and neomenthyldiphenylphosphine is a particularly preferred embodiment of this invention.

Addition of a halogen acid is necessary when an aromatic substituted alcohol is used.

The carbonylation reaction may be performed under initially neutral conditions (i. e., without the added acid) when the starting material is an aromatic substituted alkyl halide.

However, the reaction is preferably conducted under acidic conditions with an added halogen acid. A hydrohalide acid is preferred; more preferred is an aqueous hydrohalide acid that may have a concentration up to about 30 weight percent, but preferably has a concentration in the range of 2 to 20 weight percent, and more preferably is in the range of 5 to 15 weight percent. Suitable halogen acids include aqueous HCI, HBr, or HI. The preferred halogen acid is hydrochloric acid; it is especially preferred to use approximately 10 weight percent aqueous hydrochloric acid.

In the reaction vessel, the partial pressure of carbon monoxide is at least about one atmosphere (0 psig) at ambient temperature or the temperature at which the reaction vessel is charged. Higher pressures of CO may be used, up to the limits of said reaction vessel.

A pressure up to 3000 psig is convenient in this process. CO pressures that are preferred range from 100 psig to 2500 psig at the reaction temperature, and most preferred is a pressure from 250 psig to 2000 psig. It should be noted that the presence of oxygen is undesirable in the carbonylation reaction of this invention. Hence, an atmosphere of 100% carbon monoxide is most preferred to carry out this process. Various inert gases, such as nitrogen or argon, can, however, be incorporated in the reaction mass, the only criterion being that the process should not be slowed to the point of requiring exceptionally long

periods to complete the reaction.

The temperature sufficient to induce carbonylation of the aromatic substituted alcohol or aromatic substituted alkyl halide ranges from 25°C to 300°C. A more useful temperature range is from 50°C to 200°C; preferred temperatures range from 85°C to 150°C.

In order to obtain carbonylated products, the components of the reaction mixture are allowed to contact each other for a time lasting from thirty minutes to twenty-four hours.

A preferred contact time range is from one hour to twelve hours; more preferred is a range from one hour to eight hours. Optimum reaction times will vary with the choice of starting material.

The presence of a solvent is not always required in the carboxylation reaction, although it is desirable in some circumstances. When an ester or an alcohol is used as solvent, the product is usually the corresponding ester of the carboxylic acid. Any solvent in which the substances added are soluble, and which do not interfere with the desired reaction may comprise the reaction mixture. Those solvents which can be used include one or more of the following: ketones, for example, acetone, methyl ethyl ketone, diethyl ketone, methyl n-propyl ketone, acetophenone, cyclohexanone, and the like; linear, poly, and cyclic ethers, for example, diethyl ether, di-n-propyl ether, di-n-butyl ether, ethyl n-propyl ether, glyme (the dimethyl ether of ethylene glycol), diglyme (the dimethyl ether of diethylene glycol), tetrahydrofuran, dioxane, 1,3-dioxolane, and similar compounds; and aromatic hydrocarbons, for example, toluene, ethylbenzene, xylenes, and similar compounds. The preferred aromatic hydrocarbon is benzene; the preferred ketone is diethyl ketone. Ethers are also preferred; the most preferred ether is 1,4-dioxane.

The following examples are presented for purposes of illustration, and are not intended to impose limitations on the scope of this invention.

GENERAL DESCRIPTION Nuclear magnetic resonance (NMR) was used to determine the purity of the GC standard samples of 1- (4-isobutylphenyl) ethyl chloride, 1- (4-isobutylphenyl) ethanol, 1-ethyl- 4-isobutylbenzene, 2- (4-isobutylphenyl) propionic acid, and 3- (4-isobutylphenyl) propionic acid. A GC standard sample of 4-isobutylstyrene was not available, but in lieu of the standard, a sample of 1-ethyl-4-isobutylbenzene was used, because the slight difference in molecular weight (2 hydrogen atoms) does not cause a significant difference in the GC analyses. The major components of the heavy ends were identified by GC/MS and the quantity of the heavy ends was calculated using an assumed response factor based on one-

half of the average of the 1-ethyl-4-isobutylbenzene and 1- (4-isobutylpheyl) ethanol response factors.

Yields are reported in percent for Tables 1-4. Eicosane was used as a GC internal reference for all the quantitative GC determinations.

EXAMPLE 1 1- (4-isobutylphenyl) ethyl chloride (10.0 g, 97.0 wt%, 49.3 mmol), 10% HCI (20.0 g), PdCl2 (9. 0 mg, 0.0508 mmol), neomenthyldiphenylphosphine (99.0 mg, 0.305 mmol), and 1,4-dioxane (25 mL) were charged to a 100-mL Hastelloy B autoclave. The autoclave was set up in the hood and purged with CO (3 x 200 psig). The autoclave was then pressured to 700 psig with CO and the mixture was heated to 115-120°C for 2 hours. The CO pressure was kept at 900-1000 psig. The result of quantitative GC analysis is shown in Table 1.

COMPARATIVE EXAMPLE 1 The procedure of Example 1 was repeated except that Ph3P (83.0 mg, 0.316 mmol) was used as the ligand. The result of quantitative GC analysis is shown in Table 1.

EXAMPLE 2 1- (4-isobutylphenyl) ethyl chloride (10.0 g, 97.0 wt%, 49.3 mmol), 10% HCI (20.0 g), PdCl2 (9. 0 mg, 0.0508 mmol), neomenthyldiphenylphosphine (99.0 mg, 0.305 mmol), and diethyl ketone (25 mL) were charged to a 100-mL Hastelloy B autoclave. The autoclave was set up in the hood and purged with CO (3 x 200 psig). The autoclave was then pressured to 700 psig with CO and the mixture was heated to 115-120°C for 4 hours.

The CO pressure was kept at 900-1000 psig. The result of quantitative GC analysis is shown in Table 2.

COMPARATIVE EXAMPLE 2 The procedure of Example 2 was repeated except that Ph3P (82.0 mg, 0.313 mmol) was used as the ligand. The result of quantitative GC analysis is shown in Table 2.

EXAMPLE 3 1- (4-isobutylphenyl) ethanol (10.0 g, 94.0 wt%, 52.7 mmol), 10% HCI (20.0 g), PdCl2 (9.3 mg, 0.0525 mmol), neomenthyldiphenylphosphine (103 mg, 0.317 mmol), and 1,4-dioxane (25 mL) were charged to a 100-mL Hastelloy B autoclave. The autoclave was set up in the hood and purged with CO (3 x 200 psig). The autoclave was then pressured to 700 psig with CO and the mixture was heated to 110°C for 3 hours. The CO pressure was kept at 900-1000 psig. The result of quantitative GC analysis is shown in Table 3.

COMPARATIVE EXAMPLE 3 The procedure of Example 3 was repeated except that Ph3P (85.0 mg, 0.324 mmol) was used as the ligand. The result of quantitative GC analysis is shown in Table 3.

EXAMPLE 4 1- (4-isobutylphenyl) ethanol (10.0 g, 94.0 wt%, 52.7 mmol), 10% HCI (25.0 g), Pd (neomenthyldiphenylphosphine) 4 (520 mg, 0.370 mmol), and benzene (27 mL) were charged to a 300-mL Hastelloy B autoclave. The autoclave was set up in the hood and purged with N2 (2 x 150 psig) and CO (2 x 150 psig). The autoclave was then pressured to 800 psig with CO and the mixture was heated to 125-129°C for 6 hours. The result of quantitative GC analysis is shown in Table 4.

COMPARATIVE EXAMPLE 4 The procedure of Example 4 was repeated except that Pd (Ph3P) 4 (428 mg, 0.370 mmol) was used as the catalyst. The result of quantitative GC analysis is shown in Table 4.

TABLE 1 Example 1 Comparative Example 1 1-ethyl-4-isobutylbenzene 0. 06 0.12 4-isobutylstyrene 0. 01 0.05 1-chloro-1- (4-isobutylphenyl) ethane 0. 02 0.12 1- (4-isobutylphenyl) ethanol 0 0.12 2- (4-isobutylphenyl) propionic acid 93. 0 85.3 3- (4-isobutylphenyl) propionic acid 0. 28 3.65 Heavy ends 0. 50 0.63 Total closure 93. 9 90.0 Branched/linear 338 23

TABLE 2 Example 2 Comparative Example 2 1-ethyl-4-isobutylbenzene 0. 10 0.69 4-isobutylstyrene 1. 2 0.10 1-chloro-1- (4-isobutylphenyl) ethane 3. 5 0.77 1- (4-isobutylphenyl) ethanol 0. 22 0.15 2- (4-isobutylphenyl) propionic acid 89. 8 94.3 3- (4-isobutylphenyl) propionic acid 0. 16 3.5 Heavy ends 1. 0 0.56 Total closure 95. 9 100.1 Branched/linear 588 26 TABLE 3 Example 3 Comparative Example 3 1-ethyl-4-isobutylbenzene 0. 10 0.33 4-isobutylstyrene 0. 70 0.19 1-chloro-1- (4-isobutylphenyl) ethane 0. 55 0.50 1- (4-isobutylphenyl) ethanol 1. 7 1.3 2- (4-isobutylphenyl) propionic acid 90. 4 85.8 3- (4-isobutylphenyl) propionic acid 0. 15 4.0 Heavy ends 2. 1 1.6 Total closure 95. 7 93.7 Branched/linear 592 21

TABLE 4 Example 4 Comparative Example 4 1-ethyl-4-isobutylbenzene 0. 86 2.5 4-isobutylstyrene 0. 59 0.62 1-chloro-1- (4-isobutylphenyl) ethane 2. 2 3.7 1- (4-isobutylphenyl) ethanol 1.0 2.0 2- (4-isobutylphenyl) propionic acid 84. 4 45.9 3- (4-isobutylphenyl) propionic acid 0. 64 34.3 Heavy ends 11. 9 11.4 Total closure 101. 6 100.4 Branched/linear 132 1.3 It is to be understood that the reactants and components referred to by chemical name or formula anywhere in the specification or claims hereof, whether referred to in the singular or plural, are identified as they exist prior to coming into contact with another substance referred to by chemical name or chemical type (e. g., another reactant or a solvent). It matters not what preliminary chemical changes, transformations and/or reactions, if any, take place in the resulting mixture or solution or reaction medium as such changes, transformations and/or reactions are the natural result of bringing the specified reactants and/or components together under the conditions called for pursuant to this disclosure. Thus the reactants and components are identified as ingredients to be brought together in connection with performing a desired chemical reaction or in forming a mixture to be used in conducting a desired reaction. Accordingly, even though the claims hereinafter may refer to substances, components and/or ingredients in the present tense ("comprises"or"is"), the reference is to the substance, component or ingredient as it existed at the time just before it was first contacted, blended or mixed with one or more other substances, components and/or ingredients in accordance with the present disclosure.

Without limiting the generality of the foregoing, as an illustrative example, where a claim specifies that a catalyst is a palladium compound in combination with a tertiary phosphine ligand, this phraseology refers to the makeup of the individual substances before they are combined and/or mixed separately or concurrently with one or more other materials, and

in addition, at the time the catalyst is actually performing its catalytic function it need not have its original makeup--instead whatever transformations, if any, that occur in situ as the catalytic reaction is conducted is what the claim is intended to cover. Thus the fact that a substance, component or ingredient may have lost its original identity through a chemical reaction or transformation during the course of contacting, blending or mixing operations, if conducted in accordance with this disclosure and with the application of common sense and the ordinary skill of a chemist, is thus wholly immaterial for an accurate understanding and appreciation of the true meaning and substance of this disclosure and the claims thereof.

This invention is susceptible to considerable variation in its practice. Therefore the foregoing description is not intended to limit, and should not be construed as limiting, the invention to the particular exemplifications presented herein above. Rather, what is intended to be covered is as set forth in the ensuing claims.