Thionyl chloride with carboxylic acids

In analogy to the well-known condensation products of fatty acids with protein hydrolysates, a patent has also been initiated for the condensation products of ether carboxylic acids and protein hydrolysates [43]. They are made by converting the ether carboxylic acids with thionyl chloride (SOCl2) to the corresponding acid chlorides followed by the condensation with a protein hydrolysate. 

A wide range of A-acylbenzotriazoles 915 have been prepared under mild conditions in reactions of carboxylic acids with thionyl chloride in the presence of fourfold excess of benzotriazole, including R = alkyl, a-haloalkyl, a-alkoxyalkyl, alkenyl, alkinyl, aryl, and heteroaryl <2003S2795, 2004RQM275>. They represent convenient acylating agents for variety of nucleophiles. Synthetic applications of such compounds have been reviewed <2005SL1656>. 

Quinoxaline-2-carboxylic acid with thionyl chloride gives the acid chloride (79%), which undergoes the expected reactions.166 The gas-phase pyrolysis of quinoxaline-2,3-dicarboxylic anhydride (157) over a Nichrome coil gives o-phthalonitrile (158) (72%), probably via 2,3-quinoxalyne (159) which ring-cleaves, and the diisocyanide subsequently rearranges thermally to the dinitrile.167... 

The reaction of chromone-2-carboxylic acid with thionyl chloride or phosphorus halides gives the trihalide (400). This compound readily loses one of its geminal chlorine atoms and with water, for example, affords 4-chlorocoumarin through the simultaneous loss of carbon monoxide (Scheme 131) (63JGU1806). 

Phenyl-l-cyclopentanecarbonyl chloride was obtained by treatment of 1-phenyl-l-cyclopentane carboxylic acid with thionyl chloride. 

Secondly, the acidic proton is no longer present and so an acid-base reaction is prevented. Thirdly, the original OH group is converted into a good leaving group and is easily displaced once the chloride ion makes its attack. The reaction of a carboxylic acid with thionyl chloride follows the general mechanism shown below ... 

The traditional synthesis of acyl chlorides based on the reaction of carboxylic acids with thionyl chloride has been improved in various techniques. Triphenylphosphine is a cata-... 

Reaction of a Carboxylic Acid with Thionyl Chloride Section 19.2 Figure 19.2... 

An acyl chloride is an acyl group bonded to a chlorine atom. Acyl chlorides are made by reaction of the corresponding carboxylic acids with thionyl chloride. Therefore, acyl chlorides are also called acid chlorides. We consider acyl chlorides in more detail when we study acid derivatives in Chapter 21. 

Acids can be reduced to aldehydes by first converting them to a functional group that is easier to reduce than an aldehyde the acid chloride. Acid chlorides (acyl chlorides) are reactive derivatives of carboxylic acids in which the acidic hydroxyl group is replaced by a chlorine atom. Acid chlorides are often synthesized by treatment of carboxylic acids with thionyl chloride, SOCl2. 

The most widely used synthesis of acid chlorides is based on the reaction of a free carboxylic acid with thionyl chloride. A number of examples of this reaction can be found. The mechanism seems to involve an intermediate chloro sulfite, which is transformed to the acid chloride (equation 1). Polar solvents normally increase the reaction rates. ... 

VI-Halo acyl chlorides (3,35). a-Bromo acyl chlorides can be prepared In about 70-80% yield by reaetion of acyl chlorides, prepared in situ by reac-llon of carboxylic acids with thionyl chloride, which can also be employed as solvent for the bromination reaction. NBS is considerably more efficient than liromine in this reaction. Use of NCS under similar conditions gives a-chloro acyl chlorides in comparable yields. Benzyhc protons are not replaced by either leiigcnt. a-Iodo acyl chlorides can be obtained in 70-80% yield by iodination of acyl chlorides with molecular iodine in this case thionyl chloride must be iiNi d as solvent rather than CCI4 and a higher temperature (140°) is required. 

Acyl chlorides, also called acid chlorides, are easily prepared (Section 18.5) by treating carboxylic acids with thionyl chloride (SOCI2) or phosphorus pentachloride (PCI5) ... 

The most common way to prepare an acid chloride is to treat a carboxylic acid with thionyl chloride, the same reagent that converts an alcohol to a chloroalkane (Section 8.2D) ... 

The most common way to prepare an acid chloride is to treat a carboxylic acid with thionyl chloride. 

Relative reactivities of carboxylic acid derivatives toward nucleophilic acyl substitution. A more reactive derivative may be converted to a less reactive derivative by treatment with an appropriate reagent. Treatment of a carboxylic acid with thionyl chloride converts the carboxylic acid to the more reactive acid chloride. Carboxylic acids are about as reactive as esters under acidic conditions, but are converted to the unreactive carboxylate anions under basic conditions. 

Reaction of Carboxylic Acids with Thionyl Chloride... 

The retrosynthetic analysis shown for 220 allows the total synthesis. Catalytic hydrogenation of223 gives 1-pentene (see Chapter 19, Section 19.3.2), which reacts with HBr to give 2-bromopentane (Chapter 10, Section 10.2). The reaction of 2-bromopentane and magnesium metal, followed by reaction with carbon dioxide and aqueous hydrolysis, leads to the requisite carboxylic acid. Reaction of the carboxylic acid with thionyl chloride leads to the acid chloride, which reacts with dimethylamine to give 222. 

Conversion to Acid Haiides (Section 17.8) Acid chlorides, the most common and widely used of the acid halides, are prepared by treating a carboxylic acid with thionyl chloride. The mechanism, similar to that of the conversion of alcohols to chloroalkanes, involves initial chlorosulfite formation, followed by nucleophilic attack of chloride ion on the carbonyl carbon to give a tetrahedral carbonyl addition intermediate, which decomposes to give the acid chloride, SOj, and chloride ion. 

Acid chlorides can be formed by treating carboxylic acids with thionyl chloride. 

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