Benzoyl chloride catalysis

The arylation of the i-tributyistannyl glycai 717 offers a synthetic route to chaetiacandin[585,586]. The Pd-catalyzed reactions of the 3-stannylcyclobute-nedione 718 with iodobenzene, and benzoyl chloride[S87], and alkenylation with alkenyl(phenyl)iodonium triflates proceed smoothly by the co-catalysis by Cul[588,589],... 

Incorporation of extensive branching in the side chain similarly does not decrease pharmacologic activity. Reductive alkylation of aminoalcohol, 42, with isobutyraldehyde affords the amine, 43. Acylation of the amine with benzoyl chloride probably goes initially to the amide (44). The acid catalysis used in the reaction leads to an N to 0 acyl migration to afford iso-bucaine (45). ... 

Catalysis in Transacylation Reactions. The principal objective of the study was to evaluate 4 as an effective organic soluble lipophilic catalyst for transacylation reactions of carboxylic and phosphoric acid derivatives in aqueous and two-phase aqueous-organic solvent media. Indeed 4 catalyzes the conversion of benzoyl chloride to benzoic anhydride in well-stirred suspensions of CH2CI2 and 1.0 M aqueous NaHCC>3 (Equations 1-3). The results are summarized in Table 1 where yields of isolated acid, anhydride and recovered acid chloride are reported. The reaction is believed to involve formation of the poly(benzoyloxypyridinium) ion intermediate (5) in the organic phase (Equation 1) and 5 then quickly reacts with bicarbonate ion and/or hydroxide ion at the interphase to form benzoate ion (Equation 2 and 3). Apparently most of the benzoate ion is trapped by additional 5 in the organic layer or at the interphase to produce benzoic anhydride (Equation 4), an example of normal phase-... 

HCA121). 3-Acetyl-4-hydroxy-l,5,5-trimethyl-2-pyrrolone 39a gives no acetylated products with either benzoyl chloride or benzoic anhydride, or acetic anhydride. By contrast phase-transfer catalysis (K2C03/CHC13 r.t.) affords a condensation product, formed from two molecules, 39a. This product does not bear a benzoyl group (87TH2). 

Stoichiometry (28) is followed under neutral or in alkaline aqueous conditions and (29) in concentrated mineral acids. In acid solution reaction (28) is powerfully inhibited and in the absence of general acids or bases the rate of hydrolysis is a function of pH. At pH >5.0 the reaction is first-order in OH but below this value there is a region where the rate of hydrolysis is largely independent of pH followed by a region where the rate falls as [H30+] increases. The kinetic data at various temperatures both with pure water and buffer solutions, the solvent isotope effect and the rate increase of the 4-chloro derivative ( 2-fold) are compatible with the interpretation of the hydrolysis in terms of two mechanisms. These are a dominant bimolecular reaction between hydroxide ion and acyl cyanide at pH >5.0 and a dominant water reaction at lower pH, the latter susceptible to general base catalysis and inhibition by acids. The data at pH <5.0 can be rationalised by a carbonyl addition intermediate and are compatible with a two-step, but not one-step, cyclic mechanism for hydration. Benzoyl cyanide is more reactive towards water than benzoyl fluoride, but less reactive than benzoyl chloride and anhydride, an unexpected result since HCN has a smaller dissociation constant than HF or RC02H. There are no grounds, however, to suspect that an ionisation mechanism is involved. 

With 5-33.3 vol.% water/acetone mixtures, it is found136 that common-ion salts have no effect on the rate of hydrolysis of benzoyl chloride whereas the rate in 15% (but not 33.3%) water is increased by the addition of neutral salts such as lithium bromide or potassium nitrate. The increase in ionic strength on the addition of neutral salts is not the major reason for the increase in rate and nucleophilic catalysis via the more easily hydrolysed benzoyl bromide was postulated. 

Catalysis of the synthesis of benzoic anhydride and the hydrolysis of benzoyl chloride, diphenyl phosphorochloridate (DPPC), and benzoic isobutyric anhydride in dichloromethane-water suspensions by water-insoluble silanes and siloxanes, 3- and 4-trimethylsilylpyridine 1-oxide (3b and 3c, respectively), 1,3-bis(l-oxypyridin-3-yl)-l,1,3,3-tetramethyldisiloxane (4), and poly[methyl(l-oxypyridin-3-yl)-siloxane] (5) was compared with catalysis in the same systems by water-soluble pyridine 1-oxide (3a) and poly(4-vinylpyridine 1-oxide) (6). All catalysts were effective for anhydride synthesis and promoted the disproportionation of benzoic isobutyric anhydride. Hydrolysis of benzoyl chloride gave benzoic anhydride in high yield ( 80%) for all catalysts except 3a, which gave mixtures of anhydride (52%) and benzoic acid (39%). The order of catalytic activity for DPPC hydrolysis was 5 > 4 > 3b > 3a > 3c > 6. The results suggest that hydrophobic binding between catalyst and lipophilic substrate plays an important role in these processes. 

It is interesting to note that the hydrolysis of unhindered benzoyl chlorides is not catalyzed by acids, but benzoyl fluoride is acid catalyzed and follows Kq (Bevan and Hudson, 1953). Similarly, acid catalysis of benzyl fluoride hydrolysis which follows occurs (Swain and Spalding, 1960), but no acid catalysis of benzyl chloride hydrolysis is known. Furthermore, benzyl halide reactions show non-linear pa correlations (Hudson and Klopman, 1962 Hill and Fry, 1962 Swain and Langsdorf, 1951). Although much less work has been carried out on benzoyl halides, it would appear then that nucleophilic reactions with benzoyl halides resemble, in many respects, nucleophilic reactions with benzyl systems, including the considerable uncertainty as to the S l or bimolecular nature of these reactions (Thornton, 1964). 

Wamser, C. C., and J. A. Yates, Kinetics and Mechanisms for the Two-Phase Reaction Between Aqueous Aniline and Benzoyl Chloride in Chloroform, with and without Pyridine Catalysis, J. Org. Chem., 54, 150 (1989). 

The long known Reissert reaction involves the kinetic trapping by cyanide of an -acylquinolinium or -isoquinolinium salt in the classical process the acylating agent is benzoyl chloride. Reissert compounds are usually prepared using a dichloromethane/water two-phase medium recent improvements include utilising phase-transfer catalysts with ultrasound or crown ether catalysis. 

FIG. 3 Inverse phase transfer catalysis the dimethylaminop5Tidine-catalyzed reaction of benzoyl chloride and sodium salt of glycine. 

FIG. 5 Inverse phase transfer catalysis Hammett plot for the pyridine 1-oxide-catalyzed reactions of benzoyl chlorides and benzoate ions. 

Wamser. C.C. Yates. J.A. Kinetics and mechanisms for the two-phase reaction between aqueous aniline and benzoyl chloride in chlorofomi, with and without pyridine catalysis. J. Org. Chem. 1989, 54. 150-154. 

Kuo. C.S. Jwo. J.J. Inverse phase transfer catalysis. Kinetics and mechanism of the pyridine 1-oxide catalyzed substitution reaction of benzoyl chloride and benzoate ion in a two-phase waterldichloromethane medium. J. Org. Chem. 1992. 57, 1991-1995. 

Wang. M.-L. Ou. C.-C. Jwo. J.-J. Study of the reaction of glycine and benzoyl chloride under inverse phase transfer catalysis. Chem. Eng. Commun. 2000, 179. 233-252. 

The reaction of benzoyl chloride with ethanol and pyridine to form ethyl benzoate and pyridinium chloride can proceed either by nucleophilic attack of the ethanol or pyridine in the first step. With nucleophilic attack by pyridine, an acyl-pyri-dinium species forms, so this kind of reaction amounts to nucleophilic catalysis by this added base. If ethanol attacks first, the pyridine only acts to scavenge the HCl formed in the reaction. Write these two possible mechani.sms, and derive rate laws that distinguish these possibilities. 

A simple example of an acyl transfer is the reaction of an acid chloride with an alcohol (Scheme 10.21). No catalysis is necessary due to the high reactivity of an acid chloride. The alcohol performs a direct nucleophilic attack on the electron deficient carbonyl carbon. The reaction is therefore very sensitive to the nucleophile. For example, the Swain-Scott s value for acyl transfer from benzoyl chloride is 1.43, indicating that the reaction is more sensitive to the nucleophile than is the 5 2 reaction on methyl iodide. Elimination of the chloride follows a typical 1,2-elimination pathway. The proton is removed from the intermediate either prior to or subsequent to chloride departure. 

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