Und yl, dodecyl and hexadecyl sulphonates were prepared w i t h y&-label i n t h e 1 -p o s i t i o n . The syntheses r e q u i r e t h e f o r m a t i o n o f a Grignard intermediate from t h e appropriate n-1 a l k y l bromide f o l l o w e d by c a r b o x y l a t i o n o f t h e Grignard w i t h 14CO2 and subsequent e s t e r i f i c a t i o n w i t h diazomethane.
Reduction o f t h e e s t e r w i t h l i t h i u m aluminium h y d r i d e and conversion t o t h e corresponding a l k y l bromide provides a s u i t a b l e l-14C l a b e l l e d d e r i v a t i v e f o r conversion t o t h e r e q u i r e d t h i o l which i s r e a d i l y o x i d i s e d t o t h e corresponding sulphonate w i t h r e t e n t i o n o f t h e l a b e l i n t h e 1 -p o s i t i o n .
The s y n t h e t i c r o u t e provides an acceptable o v e r a l l y i e l d (18-24%) o f s p e c i f i c a l l y l a b e l l e d a l k y l sulphonat s o f h i g h p u r i t y . By using (35Slthiourea i n t h e sequence & -l a b e l l e d dodecyl sulphonate was r e a d i l y obtained. The i d e n t i t y and p u r i t y o f t h e products was confirmed by mass spectrometry, i n f r a -r e d spectroscopy, t.1.c. and reverse-isotope d i l u t i o n .