Studies on Synthesis and Dyeing Preformance of Acid Dyes Based on 4 , 7-Dihydroxy-3 , 8-di-α-naphthyl-azo-1 , 10-phenanthroline-2 , 9-dione

Some new azo acid dyes were prepared by coupling various diazotized acid components such as anthranilic acid, sulphanilic acid, laurent acid, peri acid, tobias acid, H-acid, J-acid, gamma acid, sulphotobias acid, 4-aminotoluiene-3-sulphonic acid, 5-sulphoanthranilic acid, 2-naphthylamine3,6,8-trisulphonic acid, bronner acid, metanilic acid and cleve acid with 4,7dihydroxy-3,8-di-α-naphthylazo-1,10-phenanthroline-2,9-dione. The dyes were characterized by elemental, IR and TLC analyses. Their dyeing performance as acid dyes has been assessed on viscose rayon, wool and cotton fibres.


Introduction
Some of the dyes based on 4-oxo-quinazoline ring system have been reported to be useful on natural and man-made fibres 1,2 .Acid dyes, the newest addition of existing dyes are the centre of attraction in dyestuff research 3 .The acid dyes based on 4,7-dihydroxy-1,10phenanthroline-2,9-dione (A), a heterocyclic ring system, were reported earlier 4 showed good affinity, moderate to very good light and wash fastness and good to very good exhaustion.
In continuation of our earlier work on acid dyes based on heterocyclic ring system it was thought interesting to study the synthesis, characterization and dyeing performance of various acid dyes based on 4,7-dihydroxy-3,8-di-α-naphthylazo-1,10-phenanthroline-2,9dione system.

Experimental
Melting points were determined in open capillaries and are uncorrected.The IR spectra (KBr) were recorded on a Perkin-Elmer spectrophotometer (Model 377).UV-Visible spectra were recorded on Backman DB-GT grating spectrophotometer using 1x10 -3 M aqueous solution.TLC was carried out on Silica gel-G as absorbent using reported procedure 5 .

Coupling of diazotized acid component with (A)
The coupling component (0.01 mole, 5.32 g) was suspended in NaOH (10 %, 15 mL) and the pH of the solution is maintained neutral with sodium carbonate solution (10 % w/v) to obtain a clear solution.The solution was cooled to 0-5 C and the cooled diazo solution of acid component (0.02 mole) was added drop wise with stirring, maintaining the pH to 8.0 by simultaneous addition of sodium carbonate (10 % w/v).Stirring was continued for 2 h at 0-5 C. The reaction mixture was heated to 60 C after 2 h and sodium chloride was added till the dyestuff is precipitated out.After stirring for an hour the liquor was filtered and

Dyeing of fibres
All the dyes D 1 to D 15 were applied on viscose rayon, wool and cotton fibres in 2 % shade by using the reported procedure 6 .

Fastness test
Fastness to the light was assessed in accordance with BS:1006-1978 and the wash fastness was assessed in accordance with IS:765-1979.

Table 1 .
Physical data for acid dyesAll the dyes D 1 to D 15 were applied to viscose rayon, wool and cotton fibers gave violet, blue, green, yellow, orange brown and maroon shades.D 7 , D 8 , D 11 , D 14 , D 15 gives deeper shades on all three fibers.Most of the dyes give green shades.The % exhaustion and fastness data of dyes D 1 to D 15 are given in Table-2 indicates good affinity for all the fibers used in study.The pick-up values of these dyes varied from 2 to 4. The light fastness varied from poor to fairly good whereas fastness to washing varied from fair to excellent.Exhaustion ranges from 62.00 % to 72.50 %.