Acid halides reactions with alcohol

Conversion of Acid Halides into Esters Alcoholysis Acid chlorides react with alcohols to yield esters in a process analogous to their reaction with water to yield acids. In fact, this reaction is probably the most common method for preparing esters in the laboratory. As with hydrolysis, alcoholysis reactions are usually carried out in the presence of pyridine or NaOH to react with the HC1 formed. 

The reaction is performed most simply by the addition of the propargylic alcohol to a solution of the phosphorus halide. Rearrangement of the phosphorus ester proceeds at ambient temperature or with mild heating. When phosphorus trihalides are used, the product can be isolated as the phosphonic dichloride.168169 Aqueous workup provides the phosphonic acid.162 In most instances, however, a dialkyl phosphorochloridite with only a single halogen on phosphorus available for reaction with alcohol has been used.165 170 174... 

The formation of ester via reaction (11) of Figure 12.10 deserves some further attention as it is not one of the elementary steps discussed in Chapter 2. One possible mechanism is the direct, outer-sphere attack of an alcohol or alkoxide at the acyl carbon atom, similar to the reaction of acid halides and alcohols (17-18 in Figure 12.13). This reaction is accessible for both cis and trans diphosphine complexes 12 and 13. Since monophosphines give mainly trans acyl complexes 13, not suited for insertion reactions, they were thought to have a preference for making esters or low molecular weight products. Trans complexes do form esters in reactions with alcohols or alkoxides, but this does not give direct information about the mechanism [42,43,44],... 

An acid halide can be converted to an ester by an acid catalyzed reaction with an alcohol. 

The methods discussed so far are applicable to aldehydes, ketones, esters and lactones. Hie a-haloge-nation of acids has received relatively little attention, although the traditional Hell-Vollaid-Zelinski conditions are adequate in most instances (equation 2). Alternative conditions have been developed, however, in which the acyl halide may be halogenated using NBS. ( eiKhing the reaction with alcohols or amines offers the opportunity of forming carboxylate derivatives. 

Most acid halide reactions occur by a nucleophilic acyl substitution mechanism. As shown in Figure 21.6, the halogen can be replaced by -OH to yield an acid, by -OR to yield an ester, or by -NH2 to yield an amide. In addition, the reduction of an acid halide yields a primary alcohol, and reaction with a Grignard reagent yields a tertiary alcohol. Although the reactions we ll be discus-sing in this section are jl lustra ted only for acid chlorides, they also occur with other acid halides. 

Inorganic acids also react with alcohols to form esters. In these esterification reactions, as well as HN03, H2S04 and H3P04, inorganic acid halides such as ... 

CHLORCYAN (506-77-4) CNCl C-N-CL Noncombustible gas. Violent polymerization can be caused by chlorine or moisture. Violent reaction with alcohols, alkenes, and alkynes (violent exothermic reaction) acids, acid salts, amines, strong alkalis, olefins, strong oxidizers. Contact with acid forms toxic hydrogen cyanide gas. Mixtures with benzene or cyanogen halides yield hydrogen chloride. In cmde form, this chemical trimerizes violently if catalyzed by traces of hydrogen chloride or ammonium chloride, forming cyanuric chloride. Alkaline conditions will convert this chemical to... 

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