Hydrolysis of acetyl chloride

FIRST-ORDER RATE COEFFICIENTS FOR THE HYDROLYSIS OF ACETYL CHLORIDE, BROMIDE, AND IODIDE AND BENZOYL CHLORIDE IN ACETONE/WATER100... 

On balance, therefore, the hydrolysis of acetyl chloride proceeds in non-hydroxylic solvents by a mechanism which is a mixture of ionisation (c) and some direct displacement, possibly (ft), and in hydroxylic solvents by an ionisation after the addition of water (d), possibly approximating to (c) in highly aqueous or hydroxylic media, although the apparent change in mechanism in the latter media may be a result of the change from specific to general solvation. This latter effect has been investigated in some detail by Hudson et a/.63,84. 

When a reaction occurs in the presence of a weak acid or weak base, the intermediates do not necessarily carry a net positive or negative charge. For example, the following mechanism often is written for the hydrolysis of acetyl chloride in water. (Most molecules of acetyl chloride probably are protonated on oxygen before reaction with a nucleophile, because acid is produced as the reaction proceeds.)... 

The reactions represented are the combination of hydrogen and chlorine, the decomposition of mercury cyanide, the hydrolysis of acetyl chloride, and the reaction of ethyl chloride with anamonia to form ethylamine and hydrogen chloride. The reagents are shown left and right the products are separated by the horizontal line and by a vertical line where necessary.—O.T.B.]... 

Complex kinetics, such as polymerization kinetics [19, 22], lead to complex types of behavior, even under isothermal operation, i.e., without the nonlinearity introduced by the rate constant s exponential dependence on temperature. Bailey [4] summarizes some cases of experimentally observed oscillations in CSTRs including chlorination of methyl chloride [7], hydrolysis of acetyl chloride [3], the reaction between methanol and hydrogen chloride [12], and the reaction between sodium thiosulfate and hydrogen peroxide [8],... 

The effect of isotopic substitution alpha to carbonyl group was de-determined by Bender and Feng (142) on hydrolysis of acetyl chloride, ethyl acetate, and acetic anhydride. Acetyl chloride was hydrolyzed under two sets of conditions In aqueous acetone (10-20% H2O) at —22°C., deuteration led to a 50-60% rate reduction in tet-rahydrofurane (5% H2O) at 25°C. there was no isotope effect at all. Neither was an isotope effect observed in ethanolysis of acetyl chloride in cyclohexane at 25 °C. 

More recently the acylation of aldehyde enamines has been reinvestigated (75) and shown to proceed normally when the enamine is added to the acid chloride. The morpholine enamine of isobutyraldehyde (98), on being added to an ether solution of acetyl chloride, afforded the iminium salt (99), from which the ketoaldehyde (100) was obtained in 66% yield by hydrolysis (75). 

Acetylacetone has been prepared by the reaction of acetyl chloride with aluminum chloride followed by hydrolysis,3 and by the condensation of acetone with ethyl acetate under the influence of sodium,4 sodamide,5 and sodium ethoxide,5-6-7 and by the reaction of acetone and acetic anhydride in the presence of boron trifluoride.8... 

Bevan and Hudson86 have reported that the hydrolysis of benzoyl fluoride is acid-catalysed and follows the [H30+], whereas other unhindered benzoyl halides do not. A parallel situation is found with the benzyl fluoride and chloride. Satchell87 has likewise demonstrated the hydrolysis of acetyl fluoride and chloride to be acid-catalysed. 

Investigations into the mechanism of hydrolysis and alcoholysis of acyl halides have been largely concerned with acyl chlorides and in particular with benzoyl chloride and the related aromatic acid chlorides. This was a result of the relatively slow rate of hydrolysis of benzoyl chloride compared with acetyl chloride (although their alcoholysis rates are easily measurable) and it is only comparatively recently90 that stop-flow techniques have been used to measure the faster rate of hydrolysis. However, in spite of this limitation, considerable progress has been made towards elucidation of the mechanism or mechanisms of hydrolysis and alcoholysis of these halides. 

The reactions of 0-naphthol and 4-methoxyphenol with acetyl, propionyl, butyryl, 0-chloropropionyl and chloracetyl chlorides in acetonitrile produce some striking kinetic results109. The behaviour of acetyl, propionyl and n-butyryl chlorides fit reasonably well into the pattern for acetyl chloride in nitromethane and acetyl bromide in acetonitrile. However, with chloracetyl chloride the mechanism is essentially a synchronous displacement of covalently bound chlorine by the phenol and this process is powerfully catalysed by added salt with bond breaking being kinetically dominant. When no added salt is present the rate of hydrolysis of chloracetyl chloride is ca. 8000 times slower than that of acetyl chloride. Although, normally, in second-order acylation reactions, substituents with the greatest electron demand have been found to have the fastest rates, the reverse is true in this system. Satchell proposes that a route such as... 

In an actual procedure, the carboxylic acid is reacted with an optically active a-methylbenzylamine to crystallize out the less-soluble salt in the quantities of about 50% of the whole diastereomeric salts. The double decompositions of both salts existing in the precipitate and mother liquor give the dicarboxylic acids of (+) and ( ) 60% ee, respectively. When these partially resolved carboxylic acids are recrystallized from water, the precipitated crystals are almost racemic, and the carboxylic acids of 88% ee remain in water. They can be converted into the corresponding acid anhydrides by the action of acetyl chloride. Acid anhydrides of almost 100% ee can be obtained by the recrystallization from acetone, after recovering the active acids from the mother liquor. Optically pure (+)- and (-)- ra .S -l,2-cyclohcxancdicarboxylic acids can be obtained by the hydrolysis of these anhydrides. 

Acetyl aceto-acetic ester is prepared by the action of acetyl chloride upon the compound CH3.CO.CH Na.COOC2H5, and on hydrolysis gives acetic and aceto-acetic acids ... 

Reagent grade sodium formate from J. T. Baker Chemical Co. was used it was finely ground to ensure better contact. It is imperative that extreme care be taken to ensure anhydrous conditions throughout the procedure, since hydrolysis produces formic and acetic acids, which are very difficult to remove from the product. A slight excess of sodium formate ensures a product free of acetyl chloride. 

Earlier work of this school was concerned to establish heats of formation of halogen-containing organic compounds by measuring heats of hydrolysis. Heats of hydrolysis of acetyl fluoride, chloride, bromide, and iodide402 of the chloro-substituted acetyl chlorides oi of the benzoyl halides and of chloral and bromal 3 have also been made. Comparison with heats of formation derived from heats of combustion is not normally possible, but there is a large discrepancy between the two methods for benzoyl chloride, where an early combustion measurement is available, in the sense that the determined heat of combustion appears to be about 14 kcal low. 

D) Hydrolysis of Acyl Chlorides. To a test tube containing 5 ml of water add a few drops of acetyl chloride. Observe the result immediately, and then again after shaking the tube. Repeat, using benzoyl chloride. If no reaction takes place, warm the tube. How can the products be identified ... 

Japanese chemists prepare the reagent either by the reaction of acetyl chloride with sodium formate or of formic acid with ketene. The reagent formylates amino acids in formic acid as solvent. The N-formyl group is useful as a blocking group in peptide synthesis. It is surprisingly resistant to basic hydrolysis but readily sol-volyzed in dilute acid. ... 

Reactions of acetyl chloride that are formally analogous to hydrolysis occur with alcohols, mercaptans, and amines primary or secondary compounds form corresponding acetates or amides tertiary alcohols generally yield the tertiary alkyl chlorides. Acetyl chloride can split the ether linkages of many ordinary ethers and acetals. It equilibrates with fatty acids to provide measureable amounts of the mixed acetic—alkylcarboxylic anhydride or acyl chloride, either of which may be employed in esterifications. For example, lauric acid [143-07-7], and acetyl chloride undeigo the reactions... 

In the simplest form of the Abramov reaction, the phosphorus-containing reactant is hypophosphorous acid (phosphinic acid) or an ester thereof, and in the reactions between the acid and formaldehyde or benzaldehyde the initial product is the phosphinic acid 144 (R = H or Ph.). However, the reaction can proceed further to give the bis(l-hydroxyalkyl)phosphinic acid (145 R = H or Ph) the latter (R = Ph) reacts readily with yet more benzaldehyde to give its benzylidene derivative, 5-hydroxy-2,4,6-triphenyl-1,3,5-dioxaphosphorinane 5-oxide (146 R = Ph). When acted on by a second mole of cyclohexanone in the presence of acetyl chloride, (l-hydroxycyclohexyl)phosphinic acid (147) gives the novel phosphinic chloride 148, characterized as the free acid 149 following ready hydrolysis A reaction between a phosphinic acid (150) and a second (non-identical) carbonyl compound leads to an unsymmetrical phosphinic acid (151). Esters of symmetrical 1, r-dihydroxy-substituted phosphinic acids are preparable from hypophosphite esters, H2P(0)0R ". ... 

Cuprous chloride tends to form water-soluble complexes with lower olefins and acts as an IPTC catalyst, e.g., in the two-phase hydrolysis of alkyl chlorides to alcohols with sodium carboxylate solution [10,151] and in the Prins reactions between 1-alkenes and aqueous formaldehyde in the presence of HCl to form 1,3-glycols [10]. Similarly, water-soluble rhodium-based catalysts (4-diphenylphosphinobenzoic acid and tri-Cs-io-alkylmethylam-monium chlorides) were used as IPTC catalysts for the hydroformylation of hexene, dodecene, and hexadecene to produce aldehydes for the fine chemicals market [152]. Palladium diphenyl(potassium sulfonatobenzyl)phosphine and its oxide complexes catalyzed the IPTC dehalogenation reactions of allyl and benzyl halides [153]. Allylic substrates such as cinnamyl ethyl carbonate and nucleophiles such as ethyl acetoactate and acetyl acetone catalyzed by a water-soluble bis(dibenzylideneacetone)palladium or palladium complex of sulfonated triphenylphosphine gave regio- and stereo-specific alkylation products in quantitative yields [154]. Ito et al. used a self-assembled nanocage as an IPTC catalyst for the Wacker oxidation of styrene catalyzed by (en)Pd(N03) [155]. 

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