TERT-BUTYLCHLORO- AND BROMOPHOSPHONIC ACIDS AS SOURCES OF DIOXOPHOSPHORANES

Abstract

Methods for the synthesis of free halogenophosphonic acids are developed. The first stable chloro- and bromophosphonic acids (4) are synthesized. Flash-vacuum thermolysis (FVT) of trimethylsilyl tert-butylhalogenophosphonates was performed in an attempt to generate tert-butyldioxophosphorane (5). The FVT proceeds with elimination of halogenotrimethylsilane to give unstable tert-butyldioxophos-phorane, readily transforming into trimer (7). Tert-butylhalogenophoshonic acids (9) form with triethylamine rather stable salts, which on heating eliminate triethylamine hydrohalohenide to afford trimer (7).

Key Words:

• Trimethylsilyl tert-butylchlorophosphonate
• trimethylsilyl tert-butylbromophosphonates
• tert-butylchlorophosphonic acid
• tert-butylbromophosphonic acid
• triethylammonium salt of tert-butyl-chlorophosphonic acid
• tert-butyldioxophosphorane
• trimer of tert-butyldioxophosphorane
• flesh-vacuum thermolysis