166 NOTES ApU 1019

TABLE XVIII Percentage ShrinkugP

Pattern In Area Purffled untreated. . . . . . . . . . . . . . . 38.2 Purifled' treated ... 27.1

1.0 Purifled. olelc acid added from clcrbon tetru- Purifled: olelc acid added from &ohol;"treadd

chiortdc, treated . . . . . . . . . . . . 28.2

not promote the reaction between sulphuryl chloride and wool when it is applied from solution in carbon tetrachloride, which does not swell the fibres.

(13) In the light of the above results, further experiments were carried out with benzoyl peroxide. Benzoyl peroxide (2% on the weight of conditioned wool) was dissolved in 1 C.C. of benzene, and 9 C.C. of alcohol added. The solution was then applied to a purified pattern. A second pattern was treated with 10 C.C. of a saturated solution of benzoyl peroxide in alcohol, and after both pat- terns had been dried in a current of warm air, they were conditioned and treated. with sulphuryl chloride. The results of the. milling test are given in Table XIX. .

TABLE XIX Perrrntage ShrinknRe

Pat. t,ern in Area Purlfled. unt,reatad. . . . . . . . . . . . . . . 40.4 Purllied; treuted ... 25.5

xlcdliol mixture, treated 11.8 Purilled bensoyi peroxide"Pddeci'frolil b&en&

I'nrifled. beuzovl peroxide uddc~'fkom''klcoh& trcnted . . . . . . . . . . . . . . . . . . . . . 0.3

When applied fro& a swelling solvent, therefore, benzoyl peroxide is capable of - promoting the reaction between sulphuryl chloride and wool, and it seems likely that the action of oil and soap residues, in giving the same effect with commercial fabric, is due to the presence of peroxide8 of un- eaturated fatty acids.

THEORETICAL "he manner i n which peroxides promote the

reaction between sulphuryl chloride and wool can be deduced from the work of Kharasch and Brown4. They interpret the action of benzoyl peroxide in promoting the chlorination of alkyl groups in the following manner-

Chain }starting

(CEH5CO*O), + C6Hs' + CO, + C,H,CO*O' C,H; 1- RO,CL, 3 C,H,CI + 'S0,CI

Reaction chain } 'SO,CI+ so, + C1'

C1' -+ HR -> HC1 -1 R' R' + SO,CI, --f ItCl + 'S0,CI

Schumacher and Stauff5, on the other hand, believe that reversible molecular dissociation of sulphuryl chloride into sulphur dioxide and chlorine proceeds so rapidly that reaction mixtures always contain free molecular chlorine, and the sequence of re- actions would then be as follows-

S0,Clp + so* + c1, (C,H,.CO*O), + C,Hs' + CO, t C,,H,COO

C1' + HR+ HCI + It' R' + C1, + RCI + C1'

C8Hb.+ Cl, + C,H,Cl +- CI'

Similarly, the peroxide may promote the disulphide bond breakdown essential for unshrinkability in the following manner-

SO&4 + so, + cl, (C,HbCO*O)2 + C,H,' + CO, } C , H , C O O

C,H,' + C4 + C,H,Cl + CI* C1' + R-S-5.R -+ H*SCl+ R*S'

R-S' + CL, -+ It*SCI + C1' Besides indicating that the action of sulphuryl chloride is essentially the aame as that of chlorine, the above scheme emphasises the need of intro- ducing the peroxide into the fine structure of the wool by means of swelling solvents. It also suggests that the f i s t rapid reaction, referred to in para- graph (7), continues as long as peroxide remains in the fibres, and is followed by the slower, direct reaction between sulphuryl chloride and disulphide cross-linkages when the peroxide is exhausted. Some of the practical difficulties associated with the sulphuryl chloride process may, therefore, be due to variations in the peroxide content of commercial fabrics, depending on the time of storage before treatment and the kind of soap used in scouring. More consistent results would clearly be obtained if peroxides were deliberately introduced into the wool before treatment, especially if scouring were carried out with saturated, neutral detergents. I n addition, 'continuous, instead of chscontinuous, treatment ought then to be possible on account of the greater rate of reaction between sulphuryl chloride and' wool. Similarly, the introduction of peroxides into wool before wet chlorination should be beneficial in helping to restrict attack to the surface of the fibres.

One of us (A.J.F.) is indebted to Messrs. Imperial Chemical Industries (Australia and New Zealand) Ltd. for grants which enabled him to take part in the inveatigation. TEXTILE CHEMISTRY LABORATORY

DEPARTMENT OF TEXTILE INDUSTRIES UNIVERSITY OB LEEDS

(Received on 26th Auguat 1948)

1 Nilssen, Ph.D. Thesis, Leeds University, 1937; References

Speakman, Nilssen, and Elliott, Nature, 1938, 142, 1036. Hall, Hicking, and Pentecost, B. P . 464,503 (thiR

Hall, this Journal, 1939, 55, 389. ElIiott and Speakman, J.C.S., 1940, p. 041.

Schumacher and Stauff, C'hemir. 1942, 55, 34 I .

Journal, 1937. 53, 336);

4Kharasch and Brown, J . Amer. Chem. Soc., 1939, 61, 2142, 3432.

Notes Meetings of Council and Committees Colour Index Editorial Panel- 16th -

March Council- No meeting was held Finance- 22nd

Vat Dyes- 16th Photochemistry Symposium- 17th AbBtractors- 11th Chairmen and Honorary Secretaries of Local

Publicatio- 16th St30tion0- 26th