Surfactants with controlled half-lives

✍ Scribed by Krister Holmberg

• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 606 KB
• Volume: 1
• Category: Article
• ISSN: 1359-0294
• DOI: 10.1016/s1359-0294(96)80094-x

✦ Synopsis

Surfactants with controlled half•lives normally contain a bond that is susceptible to either acid or alkaline hydrolysis. In recent years particular attention has been directed towards ester-containing quaternary ammonium surfactants, 'ester-quats', which readily break down under alkaline conditions. Surfactants containing acetal and ketal groups have been widely studied as acid-labile compounds. The main incentive behind the development in this area has been the synthesis of surfactants that will biodegrade rapidly.

review. The focus is on literature published between April 1994 and April 1996. Figure 1 Structures of one conventional quaternary ammonium surfactant {Jj and three ester-quats (II-IV). R is a long chain alkyl, and X is CI, Br or CH 3 S0 4•

Surfactants susceptible to alkaline hydrolysis

The ester bond is the natural choice as the alkali-sensitive linkage in surfacrants. Surface active esters are also good substrates for lipases. This approach of obtaining rapidly degradable surfactants has attracted particular attention in the important areas of fabric softener and hair conditioner. The traditional surfactant used for these applications is dioctadecyldimethylammonium chloride and homologues thereof. During recent years there has been a rapid switch to ester-containing quaternary ammonium compounds, 'ester-quais', with improved ecological properties. All major producers of detergents use ester-quats in commercial softener formulations today [1,Z,PI-P6j. Figure 1 shows structures of some relevant surfactants of this type.