SYNTHESIS AND CHARACTERIZATION OF SOME AZO-ANIL DYES

A number of azo-anil dyes of the type [GRAPHICS] with Y=CN or NO2 and R,R'=Me, Me; Me,C6H13; Et,Pr and C6H13,C-6,H-13 were synthesized by re actions of the aminosubstituted nitrosoamine with phenylene diamine fo llowed by condensation of the resulting aniline with the appropriate 4 -substituted benzaldehyde. Mesomorphic properties were determined both by hot-stage polarizing microscopy and DSC. A nematic phase was obser ved only when R=R'=CH3 while smectic A phases occurred in the other ho mologs. Melting temperatures were greater than 130 degrees. All had co lors ranging from red to orange with UV lambda(max) ranging from 448-4 59 nm and epsilon 2.20-3.67 E+4. The Delta H melting values ranged fro m 16.8 to 30.7 KJ/mole and solubilities in a BDH-E7 liquid crystal mix ture were low.