Bul l . SOC. Chim. Belg. vol.91/no 5/1982

PREPARATION OF SOME CHOLESTERIC COMPOUNDS AND STUDY

OF T H E I R MESOPHASES.

A . K . S a r k a r and D.C. Pa ra sha r .

Chemistry S e c t i o n , Na t iona l P h y s i c a l Labora to ry , N e w Delhi-110012, I n d i a .

New methods have been developed f o r t h e p r e p a r a t i o n of c h o l e s t e r i c d e r i v a -

t i v e s . C h o l e s t e r y l c h l o r i d e has been prepared by t h e r e a c t i o n of c h o l e s t e r o l

and t h i o n y l c h l o r i d e a t room t empera tu re . C h o l e s t r y l esters d e r i v e d from open

cha in a l i p h a t i c a c i d s l i k e nonanoic a c i d , o l e i c a c i d , s tear ic a c i d have been

prepared by s imple condensat ion of c h o l e s t e r o l and r e s p e c t i v e a c i d i n t h e

presence of p- toluene su lphon ic a c i d as c a t a l y s t . A l a r g e number of c h o l e s t e -

r y l n -a lky l ca rbona te s l i k e c h o l e s t e r y l o c t y l c a r b o n a t e , c h o l e s t e r y l o l e y l

ca rbona te have been prepared. Melt ing p o i n t s and p u r i t y of t h e s e compounds

have been determined. Melt ing p o i n t s of t h e s e compounds ag ree wi th t h e

e a r l i e r d a t a and t h e y i e l d i n each c a s e has been found t o i n c r e a s e 2 0 t o 30%.

A l l t h e s e compounds have been i n v e s t i g a t e d under t h e p o l a r i s e d microscope and

a l s o by t h e c a p i l a r y method t o i d e n t i f i y t h e mesomorphic phases . The tempera-

t u r e and t h e l a t e n t h e a t of each t r a n s i t i o n was determined by D i f f e r e n t i a l

Scanning Ca lo r ime te r and t h e d a t a i s t a b u l a t e d i n t h e pape r . I t is found t h a t

most of t h e s e compounds e x h i b i t c h o l e s t e r i c as w e l l as smectic phases . E f f o r t s

have been made t o p repa re h ighe r members of esters and a l k y l c a r b o n a t e s t o see

a d d i t i o n a l phases wi th i n c r e a s i n g cha in l eng th . The r e s u l t s a r e d i s c u s s e d i n

t h e paper .

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