I

I

f I I ,

d - Bleached

I I l 0 1% O.W.W.

I 0 2%o.w.w.

A 3% O.W.W.

P 4%0.W.W.

I I

I

I

Cubex wash time, min

Figure I - Effect of different concentrations of Synth- appret BAP/lmpranil DlN treatment on the felting shrinkage of unbleached and bleached wool single jersey fabric. For silicate-stabifised bleaching procedure - see text

this sequence produced the highest whiteness and slightly less chemical damage than another chemical shrink-resist treatment evaluated, i.e. chlorination.

Comparison of bleaching with hydrogen peroxide in the presence of either the silicate- or the phosphate-based stabilisers shows that the former technique allowed a sav- ing of 60°/0 in treatment time. In addition, use of the silicate-based stabiliser gave a 35% saving in chemical costs over the other stabiliser. Although bleaching with the silicate-based product results in a higher alkali solubility, this is still below the 30% limit regarded as acceptable [31. There was no major difference in the whiteness and yel- lowness indices achieved in the two bleaching techniques. A separate paper will describe the optimisation of hy- drogen peroxide bleaching in the presence of a silicate- based stabiliser [161.

The Use of Proprietary Names The fact that proprietary chemicals are mentioned in this paper in no way implies that there are no substitutes that may be of equal or better value.

* * *

The authors are indebted to Mr S N Myciunka for techni- cal assistance.

REFERENCES 1. Wool Science Review, 30 (1966) 16. 2. Wool Science Review, 31 (1967) 1. 3. Rosch, Textilveredlung, 84 (1966) 628. 4. Rosch, Textilveredlung, 84 (1966) 760. 5. Schmidt, 2. ges. Textilindustrie, 69 (1969) 401. 6. Cegarra, Rib6 and Gacen, J.S.D.C., 80 (1964) 123. 7. Cegarra, Gacen and Caro, J.S.D.C., 94 (1978) 85. 8. Cegarra, Arbeitstagung, Deutschen Wollforschungsinstitut Aachen,

9. Jacquemart, Teintex, 27 (1962) 79, 163. (Oct 1980). 85 (1981) 66.

10. ASTM Test for Yellowness of Plastics, D 1925-73. 11. Benisek, IWS Product Development Report No. 134 (1971). 12. IWS Washable Products Technical Bulletin No. 15 (Jan 1981). 13. Allanach et al., Proc. 6th International Wool Text. Res. Conf., Pretoria

(19801, 5, 61. 14. CocketI et al., J.S.D.C.. 96 (1980) 214. 15. Wool Science Review, 17 (1960) 18. 16. Palin, Teasdale and Benisek, J.S.D.C., (In press).

Crystal Data for C.I. Pigment Yellow 6 A Whitaker Department of Physics Brunel University Uxbridge Middlesex

The single-crystal data and X-ray powder pattern are reported for C.I. Pigment Yellow 6 la-[ ?-hydroxy- eth ylidene lacetanilide- a-azo- [4'-chloro-2'- nitrobenzene]). The powder pattern has been indexed from the cell dimensions given by the single-crystal measurements. The problems of multtple indexing have been reduced by comparison with observed structure factors.

INTRODUCTION Accurate information about the arrangement of colorant molecules in crystals is essential to the understanding of the way in which the light absorption of these molecules is related to the coloration properties of pigment particles in practical use. As part of the information needed and with the immediate aim of providing accurate X-ray data for analytical purposes, this article is one of a series in which have been reported X-ray powder diffraction data obtained from crushed crystals of pigments. A complete list of these articles and the reasons for using crushed crystals rather than powder specimens have been given previously [l].

JSDC Volume 99 MayIJune 1983 157

ORIGIN OF SPECIMEN C.I. Pigment Yellow 6 (C.I. 11670) has the molecular struc- ture shown in Figure 1. Although the crystal structure has been reported [21, no atomic parameters have been given and no powder data are available. During a redetermina- tion of the structure, the opportunity was taken to obtain powder data. Single crystals were prepared by making a saturated solution of the commercial pigment, Recolite Fast Yellow 3G(RCL)*, in toluene at 80°C. This was placed in an oven and the temperature raised to 85°C to ensure that the pigment was completely dissolved. The solution was then cooled to room temperature over a period of about two weeks.

p 3

Figure 7 - C.I. Pigment Yellow 6

OPTICAL EXAMINATION Most crystals were needle shaped up to 5x0.3x0.3 mm in size, but some were blades up to 4x0.5x0.3 mm. Both types of crystal showed a monoclinic aspect, with a mono- clinic angle of about 11 I".

The crystals exhibited oblique extinction on the blade face, but the extinctions were not sharp. One extinction direction was about 19"from the length in the obtuse angle.

'This product is no longer listed in the Colour Index. - Editor

This made the other extinction direction approximately along the edge of the crystal.

In addition the crystals were pleochroic. With the plane of polarisation parallel to the length of the crystal the colour was a light greenish yellow, while with the plane of polar- isation perpendicular to the length the yellow colour was darker with an orange tinge.

Mirror twinning was observed, but much less frequently than in the case of C.I. Pigment Yellow 1, (C.I. 11680) [3]. It is claimed that these two pigments are isomorphous [2].

X-RAY EXAMINATION Laue photographs confirmed that the crystals belonged to the monoclinic system with the unique axis (b) parallel to the thickness of the blade, the a and c axes were originally defined by the morphology of the crystal, the a axis being taken as parallel to the length of the blade.

Weissenberg photographs were taken about thesea and c axes with filtered copper radiation; from these, approxi- mate cell dimensions and systematic absences were determined (hOl absent when / is odd, OkO absent when k is odd).

a=7.48?0.07& b=19.8~0.2~,c=11.63~0.2 A,P=111?2°, space group P2,/c. These values agree with those given previously 121.

The observed density (Do) was obtained by flotation in a mixture of carbon tetrachloride and trichloroethylene.

The intensity measurements for determining the crystal structure were made on an automatic diffractometer of the National X-ray Crystallographic Service. This was pro- grammed to give a different unit cell, one that gave p closer to 90".

The results of these observations were:

TABLE 1

X-ray Powder Data for C.I. Pigment Yellow 6 -

I

9.82 020 7.23 021 5.58 031

5.36 ] ::f 5.17 ] yi; 4.89 040

4.71 1 :zi 4.46 041 4.14 131

3.99 ] ;;;

3.59 I 200

3.67 I 9:; 141

3.53 1 ;; 3.400b

212 200 132

3.257b { ;2:

9.784 7.234 5.576 5.372 5.328 I 5.141 4.892

4.709 4.452 4.126

3.974

3.658

3.587 3.528 3.454 3.436 3.401 3.401 3.368

3.234

100 53 61

33

22

5

34

8 13

12

35

37

28

67

89

052

3.136 iii 21 1

3.053 ] ;i: 2.957 ] 16i

2.900 1 i:z 2.826 242 2.703 004

2.651 1 lz! 170

2.597 024 252

2.482 1 :$ 080 2.450 1 17i

2.414 063

2.375 1 :!!: 2.337 242

2.316b 1 ii: 2.225 ::!

24i

d c a l c I

3.163 3.143

3.121 3.112

3.013 2.963 ( 2.949 )

2.822 5 2.686 5

2.642 2.605

2.590 2.506 2.480

2.441 2.41 1

2.369 2.340 4

2.315

2.223

4

debs hkl

270

2.205 ] y i z 31 1 1 34

2.177 { 272 1 63 233

2.118 164 135

2.078 352 2.036 145 2.016 173

281

204 1.911 { 115

332 283

1.886 { 164 055

1.862 402 I if

d c a l c I

2.205

2.198 2.195 2.182 2.173 1 6 2.168 2.122 2.115 ) 5 2.1 14 2.076 4 2.032 5 2.013 5 1.996 1.993 1 1.932 6 1.925 I 1.913 1.909 1 6 1.904 1.890 1.888 1 9 1.884

1.863 1.870

1.862 1.859

-

158 JSDC Volume 99 May/June 1983

I 263 j 0,10,2 ;! \ 422

206 1.808 1 084 1.788 423

1.751 1 ;:: 1.706 2,10,2 1.674 434

1.626 1 O 2 f i o

1.583b 1 is 1.554 176 1.421 236 1.375 481 1.338 077 1.324 2,12,3

1.849 1.844 1.843 1.839 1.829 1.829

1.809 I 1.786 1.750 1.750 1 1.703 1.669

1.628 I 1.593 1.580 I 1.550 1.416 1.393 1.345

1.262

1.234 I

8

4

4

5

3 5

5

5

4 4 5 5 6

5

4

b Broad diffuse line

The results of these observations were a=7.462a0.001 8, V=1569.010.6 b=19.568&0.002 8, Z=4 c=11.175-~0.001 8, D,=1.527+0.001 g/cm3 p=105.96?0.01" D,=I .52740.005 g/cm3 Space group P2,/n Transforming these observations to the orientation of the

morphological values gives c=l1.579~0.001 8, and p=111.9O-tO.O1", in good agreement with the photographic data.

The observed density is in reasonable agreement with that reported previously: 1.520 g/cm3 [Z].

POWDER DATA The X-ray pattern was obtained with an 11.46 cm

Debye-Scherrer camera and filtered cobalt radiation (CoK,,=1.79020 8,) and the films photometered. The observed and calculated spacings and relative intensities are listed in Table 1. The Miller indices given are based on the unit cell from diffractometer data. The problem of mul- tiple indexing was reduced by reference to the observed structure factors. The patterns of the recrystallised and as-received compound are in agreement with each other. There are no obvious similarities between this pattern and that for C.I. Pigment Yellow 1 in spite of the fact thatthey are claimed to be isomorphous [2].

REFERENCES 1. Whitaker, J.S.D.C., 99 (1983) 121. 2. Mez, Ber. Bunsenges. Physik. Chern., 72 (1968) 389. 3. Whitaker, J. Appl. Cryst., 14 (1981) 69.

Thin Layer Chromatographic Behaviour of Some Novel Analogues of Phthalein Dyes R P Chamoli* and R P Thapliyalt *Department of Chemistry Govt Postgraduate College Gopeshwar (Chamoli) Uttar Pradesh India

tBirla Constituent College Garhwal University Srinagar (Garhwal) Uttar Pradhesh India

Thin layer chromatographic studies of some novel analogues ofphthalein dyes have been carried out using silica ge l G as adsorbent and five different solvent systems as developing media. A convenient and efficient method for identification, purification and separation of these new dyes has been developed.

INTRODUCTION Thin layer chromatography (t.1.c.) is an invaluable tool in the investigation of virtually al l classes of organic com- pounds. In the field of synthetic dyes, application of this technique has been made extensively. Rettie and Haynes 1 I] separated sulphophthaleins on silica gel G using benzene-isopropanol-acetic acid (60:40: I ) , ethyl acetate-pyridine-water (60:30: 10) and amyl alcohol- ethanol-ammonia(conc.) (50:45:5) solvent systems. Waldi [2] used alumina G-silica gel G (1:l) layers and ethyl ace- tate-methanol-ammonia (5 mol/l) solution to identify and determine the purity of acid dyes used as indicators. In addition, there are some more reports [3-71 on t.1.c. separa- tion of acid dyes on silica gel G layers.

We have reported recently on a programme of research aimed at obtaining unsymmetrical phthaleins [81, in which some novel analogues of phthalein dyes (IV-XI) were synthesised by the condensation of two y-keto acids, (2-10- b:omobenzoyllbenzoic acid (la) and 2-@-bromobenzoyl]

tetrachlorobenzoic acid (Ib)) with various phenols (Ill) in the presence of concentrated sulphuric acid. y-Keto acids reacted with phenols through their lactol tautomeric form (II), as shown in the Scheme. The dyes so obtained are unsymmetrically substituted phthalides, in which the cen- tral triphenylmethane carbon is attached to two different rings. Hence, they have been named as phthal-as-eins; 'as' represents the dissymmetry and 'ein' the class of the com- pound (phthalein). Absorption maxima of these dyes were studied in absolute ethanol (neutral and alkaline media) and were found to be quite close to those of the correspond- ing true phthaleins [81.

In the present paper we report the t.1.c. behaviour of the above-mentioned phthal-as-eins (IV-XI) on silica gel G layers, making use of five different eluents. This work has been undertaken in order to find a suitable method for identifying, purifying, and separating these newly synthe- sised dyes. The method described here may also serve as a basis for the identification of other analogous compounds in this group of synthetic dyes.

EXPERIMENTAL The t.1.c. plates (thickness 3 mm) were prepared by spread- ing silica gel G (Merck)-distilled water (1:Z) slurry, drying first at room temperature for 30 min, then at 100-1 10°C for 1 h in an oven, and cooling in a desiccator.

The phthal-as-eins (IV-XI) (0.1% wt/vol. in methanol) were applied to the layers with a micropipette and chromatograms were eluted in jars saturated with solvent vapour from one of the systems S, to S, at a constant temperature (25? 1 "C).

S, - ethyl acetate-methanol-ammonia (5moVl) (40:40:20) S, - ethyl acetate-pyridine-water (60:30: 10) S, - n-butanokthanol-ammonia (sp.gr. 0.880)- pyridine (40 : 1 0 :30 :20) S, - n-butanol-acetone-water-ammonia (sp.gr. 0.880) (5:5:1:2) S, - benzene-acetic acid (9O:lO).

JSDC Volume99 May/June 1983 159