Ketene chemistry amine reactions

General Reaction Chemistry of Sulfonic Acids. Sulfonic acids may be used to produce sulfonic acid esters, which are derived from epoxides, olefins, alkynes, aHenes, and ketenes, as shown in Figure 1 (10). Sulfonic acids may be converted to sulfonamides via reaction with an amine in the presence of phosphoms oxychloride [10025-87-3] POCl (H)- Because sulfonic acids are generally not converted directiy to sulfonamides, the reaction most likely involves a sulfonyl chloride intermediate. Phosphoms pentachlotide [10026-13-8] and phosphoms pentabromide [7789-69-7] can be used to convert sulfonic acids to the corresponding sulfonyl haUdes (12,13). The conversion may also be accompHshed by continuous electrolysis of thiols or disulfides in the presence of aqueous HCl [7647-01-0] (14) or by direct sulfonation with chlorosulfuric acid. Sulfonyl fluorides are typically prepared by direct sulfonation with fluorosulfutic acid [7789-21-17, or by reaction of the sulfonic acid or sulfonate with fluorosulfutic acid. Halogenation of sulfonic acids, which avoids production of a sulfonyl haUde, can be achieved under oxidative halogenation conditions (15). 

This paper will describe the reactions of ketene aminals, 1, more highly activated electron-rich alkenes, with isocyanates to again afford amide products. We shall initially discuss the chemistry of the ketene aminal/isocyanate reaction, the preparation of these activated monomers and sane properties of solution-derived model "hard segments". 

The facile reaction of ketenes with alcohols and amines led to investigations of the possible utihty of ketenes in polymer chemistry more than 75 years ago. There is renewed interest in the utilization of ketenes in polymer chemistry, and this work has been reviewed, including many examples of ketenes derived from Meldrum s acid derivatives. 

Ketenes react readily with amines forming amides and with alcohols forming esters, and the utilization of such reactions in polymer chemistry has long been of interest. In a recent study the Meldrum s add derivative 213 was prepared, and has dual reactivity by cHck addition for attachement... 

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