LVILLIAMA.PRYOR ANI) GERALD L. KAPLAX
4234
the tracer method and the molecular weight methods for obtaining transfer constants must await the COTTIpletion of those studies. Acknowledgment.--This work was silpported in part by Contract AT (11-1)-1169 (at Purdue) and by AT
[CONTRIBZ'TIOS FROM THE
lro1. X(i
(40-1)-:3180 (at LSU) from the .ltomic Energy Coinmission and by Public Health Service Research grants from the Yational Institutes of Health a t both Purdue and L S U Grateful acknowledgment is made to the donors of these funds
DEPARTMEXTS OF CHEMISTRY O F LOUISIASASTATE LSIYERSITY, BATON R O U G E , LOVISIANA, ASD P U R D U E CSIVERSITY, LAFAYETTE, IXDIAX.41
Reactions of Radicals. BY ~
~
1
X.
Butyl Peroxide
X.1PRYOR' ~ 1A N D~ GERALD ~ ~ L. K A P L A N ~ RECEIVEDJASUARY 25, 1964
By techniques similar to those used in the previous paper,3 the rate constant for dissociation and the chain transfer constant are obtained for but>-l peroxide a t 60 and 80" in styrene. At BO", the dissociation rate constant is 3.3 X sec.-l using either dioxane or benzene as solvent. The transfer constant is 7.6 X in dioxane-styrene mixtures and 0.2 X lo-: in benzene-styrene a t 60". The activation energy is 34.3 kcal.jmole for the unirriolecular dissociation step. The activation energy for transfer, Et,, is 23 kcal./mole if the value of 7.3 kcal. /mole is taken for E,,. The OlivC&Scliulz method of calculating molecular weights of polymers, which takes into account changes iii molecular weight distribution \vith differing amounts of transfer, is discussed briefly
Introduction Butyl peroxide, a representative straight-chain dialkyl peroxide, can be synthesized in good yield \Ye wished to study this peroxide to extend and confirm our data on propyl peroxide and to allow comparison of butyl peroxide with the previously studied t-butyl peroxide Y o previous rate studies have been reported for butyl peroxide
unsymmetrical triplet a t 0.90 p.p.ni. with relative intensity of 1.50 due t o the three 6 hydrogens. The very easily obtained n.m.r. and infrared spectra are entirely adequate analyses for purity.5 They are safely and rapidly obtained, and control solutions containing 1% of the expected impurities shoiv large, easily detectable peaks. I t is recommended t h a t these analyses be used in place of elemental analysis, which is hazardous, or refractive index, which is insensitive to impurities.
Data Experimental Preparation of Butyl Peroxide.---Butyl methanesulfonate wa5 prepared by the method of m'illiarns and Mosherl on a 6.0-mole scale. T h e sulfonate ester was distilled through a 6-in. Vigreux colurnn ( b . p . 66" a t 0.2 t r i m . 1. The yield of distilled ester was :Or;. The peroxide was prepared by the ?rloslierj method using 367 g. of sulfonate, 120 g . of 30';;, hydrogen peroxide, and L'B1 g. of SOYc aqueous KOH. The peroxide was distilled through a 6in. I-igreux column a t 61" and 20 m m . , and yields of 30 tu 40ci of distilled material were obtaiiied. Peroxide Purity.--.ln elemental analysis was obtained on one sample and gave 66.70'; C anti 12.86"; H , in agreement with the calculated 65.71 and l ' 2 . 4 1 r ~ . f l o n r w e r , elrnrentnl !ii?nl:
