Advan tages The assessment is objective and the information is ob- tained quantitatively. The test method is rapid and can be automated.

Disadvan tages Investment costs are high. The samples are only small and information on specks is only possible by using a micro- scope.

5 CONCLUSIONS Only the test methods for textile dyes related to application are dealt with in this report. Process control methods for

t should generally be possible to carry out a test easily nd rapidly. Good reproducibility and the provision of eliable information on the behaviour of the dispersion in pplication under practical conditions are the aim.

he filtration (e.g. AATCC) and speck tests described eet most of these requirements. Both these test metho- ds, especially in combination, provide a good picture of he dispersion behaviour and dispersion properties of a extile dye.

n the other hand, the flow tests and stability tests at igh temperature without substrate provide little informat- ion on the technical application properties of the dye

production are not discussed. For all the methods described, the provision of a

representative sample is an important prerequisite for obtaining reproducible and reliable results. The tests should be carried out immediately after preparing the samples in order to avoid any change in the test dispersions such as agglomeration or sedimentation.

ormulation. From an objective standpoint there is always he danger of false interpretation with these tests.

he other methods supplement the filtration and speck ests and can be carried out in addition to the usual ethods in special cases. The instrumental physical test ethods should be given special mention here as they will

Crystal data for C.I. Solvent Yellow 56

A Whitaker

Department of Physics, Brunel University, Uxbridge, Middlesex UB8 3PH

The single crystal data and X-ray powder pattern are reported f o r C.I. Solvent Yellow 56 (l-phenylazo-4- N,N-diethylaniline). T h e powder pattern has been indexed f r o m cell dimensions given by single crystal measurements. T h e problems of multiple indexing have been reduced by comparing the powder data with obserued single crystal intensities.

INTRODUCTION This note is one of a series [l-51 in which have been c2 H5

reported X-ray powder diffraction data obtained from crushed single crystals, with the aim of providing accurate X-ray powder data for analytical purposes. One earlier paper [I] examined the usefulness of X-ray powder diffrac- tion to colour chemistry and gave a complete list of articles to that date.

e N = N e / c2 H5

Figure 1 - c.1, Solvent yellow 56

ORIGIN OF SPECIMEN C.I. Solvent Yellow 56 (C.I. No. 11021) has the molecular structure shown in Figure 1. X-ray data have been reported for this dye. Single crystals were prepared by making a hot saturated solution of the commercial material Waxoline Yellow E (ICI) in toluene at 85°C. This was placed in an oven, the temperature increased to 95°C to ensure com- plete saturation and then the solution cooled to room temperature over a period of three weeks.

OPTICAL EXAMINATION The recrystallisation gave predominantly yellow plate- shaped crystals of all shapes and sizes, many with inter- growths, in addition to a few acicular crystals up to 6 x 0.6 x 1 mm in size but with irregular ends.

The optical observations were made on the latter group of crystals. The crystals were pleochroic: with the plane of polarisation parallel to the length the crystals were light yellow, with the plane perpendicular the colour changed to a reddish-orange. The crystals exhibited straight extinction parallel to the blades.

X-RAY EXAMINATION Laue photographs indicated that the crystals belonged to the monoclinic system with the unique axis parallel to the length of the blade. The other crystallographic axes, a and c, were defined as parallel to the breadth of the blade and through the thickness respectively.

Weissenberg photographs were taken of crystals mounted with b and c axes along the oscillation axis using filtered copper radiation and gave approximate cell dimen-

218 JSDC Volume 105 May/June 1989

TABLE 1

Powder data for C.I. Solvent Yellow 56

hkl dcdk I h k l dc,k

10.74 7.48 5.75 5.33 4.96 4.83 4.39 4.26 4.16

3.79

3.72

3.57

3.53 3.420 3.346 3.248

3.146 3.101

3.026b

2.900

00 1 io i 110 iii 102 111 012 102

20 1 112

{ :;: { K

{

{ %

21i 112

103

212 21 1

202 022

212

10.741 7.467 5.740 5.320 4.984 4.840 4.382 4.265 4.164 3.840

3.790 3.766 3.717

3.574 3.537 3.426 3.349

3.238 3.246 I 3.144 3.097

3.017 3.047 I 2.904

29 10 6

20 8

100 12 8

16

55

6

6

2 2 7

40

2 3

3

14

2.870 2.836 2.744 2.709 2.600 2.419 2.346

2.328 2.256 2.185 2.091

2.062b 2.034 2.003 1.968

1.920 1.860

1.836 1.816 1.793 1.738 1.621 1.612

220 122 310 30 1 023 222 131

{

{ ::: { { ;;;

132

314 231

403

232 215

412

141 423 24 i 242 333

2.870 8 2.833 8 2.733 4 2.710 3 2.603 3 2.420 7 2.345 3

4 2.318 2 2.254

2.184 3 2.092 7

2.333 I 3 2.065

2.037 3 2.004 2 1.970 6

1 1.913 2 1.861

1.834 I 1.815 3 1.794 1 1.737 2 1.623 2 1.613 2

I

b - broad diffuse line

sions of a = 8.94k0.09 A, b = 7.61k0.08 A, c = 11.OkO.1 A, p = 101k2". The systematic absences were also determined (OkO absent when k is odd).

The intensity measurements for the crystal structure determination were obtained using an automatic diffrac- tometer of the National X-ray Crystallographic Service. This also gave accurate cell parameters.

The usual method of determining the density by observ- ing floating crystals in a mixture of miscible liquids failed because of the solubility of the crystals in most available organic liquids. However, the density appeared to be between that of enthanediol(l.11) and carbon disulphide (1.26).

a = 8.9244+0.0008 A b = 7.5805k0.0014 A

p = 99.996+0.006" Space group P2, or P2Jm

The results of these measurements were: V = 726.6k0.2 A3 1.11<Oo<1.26 g/cm3

c = 10.9067k0.0006 A Z = 2 Ox = 1.1478k0.0003 g/cm3

POWDER DATA The X-ray pattern was obtained using an 11.46 cm diameter Debye-Scherrer camera and filtered cobalt ra- diation (CoKm = 1.79021 A) and the films were photome- tered. The observed and calculated interplanar spacings and relative intensities are listed in Table 1. The problem of multiple indexing was reduced by reference to the observed single cystal intensities. The patterns of the 'as received' and recystallised samples were in agreement. The patterns of 'as received' samples of C.I. Solvent Yellow 56 from other manufacturers, i.e. Oil Yellow GGS (KKK) and Oilsol Yellow DEA (W) were also examined. These patterns agreed with the others.

REFERENCES 1 . 2. 3. 4. 5.

A Whitaker, J.S.D.C., 102 (1986) 66. A Whitaker, J.S.D.C., 102 (1986) 109. A Whitaker, J.S.D.C., 102 (1986) 136. A Whitaker, J.S.D.C., 103 (1987) 270. A Whitaker, J.S.D.C., 104 (1988) 225.

JSDC Volume 105 May/June 1989 219