he presence of traces of impurities in commercial isoprene obtained from petroleum has a profound influence on the qualities of the isoprene for polymerization purposes.Of these impurities the paraffins, cycloparaffins, and simple acetylenes have little or no effect. The monoolefins, for the most part, have a slight retarding influence on polymerization rate in emulsion. Certain olefins, however. having the structural unit ^/C=CCII<^, have a substantially larger retarding effect than the others. This includes such compounds as 3-methyl-l-butene, isoprene

zene; Í is flow time for polymer solution; t is concentration of polymer in grams per 100 ml. of benzene. Summary 1. Syntheses are described for 3-methoxystyrene, 4-methoxystyrene, 4-methoxy-3-methylstyréne, 6-methoxy-3-methylstyrene, 5-isopropyl-4-methoxy-2-methylstyrene, 3,4-dime thoxystyrene and 4-phenoxystyrene.2. The formation of substituted styrenes by chloroethylation is discussed.3. An unusual reduction occurs in the catalytic dehydration of 1 -(4-phenoxyphenyl) -ethanol by means of alumina to give 4-phenoxyphenylethane as a by-product.

M o s t copolymers of butadiene (75 parts) with vinyl monomers (25 parts) are rubbery, but the quality of the elastomers varies greatly with the nature of the vinyl monomer. Of four comonomers herein described 2-vinylthiophene and methacrylonitrile form copolymers which compare favorably with GR-S; 2-vinylfuran and vinylidene chIoride do not. The copolymer with Z-vinylfuran is different from GR-S; it is benzene-insoluble, produces high modulus and low elongation stoclcs, and has inferior flexcracking resistance. The copolymer with 2-vinyIthiophene is similar in properties to GR-S. The methacrylonitrile copolymer is also similar, but superior to GK-S in respect to the baIance between hysteresis-temperature rise and flex-cracking resistance. The butadiene-vinylidene chloride copolymer is poorer than GR-S in this respect.HE copolymerization of butadiene with a large variety of vinyl monomers has been of much recent interest in the search for new and useful synthetic rubbers. In the present work are described the copolymers of butadiene with two analogs of styrene, 2-vinylfuran, and 2-vinylthiophene, as well as with methacrylonitrile and vinylidene chloride. STARTING MATERIALS%VINYLFURAN was furnished by E. C. Lathrop of the Northern Regional Laboratories and was distilled directly before use; b.p. ~-VINYLTHIOPHEND was prepared by the catalytic dehydration with potassium hydroxide of 2-(2-hydroxyethyl)-thiophene. The latter compound was furnished us by C. A. Weisgerber of Pennsylvania Strtte College. The apparatus and technique are those described by Frank, Adams, Allen, Gander, and Smith (1). From 258 grams (2.01 moles) of 2-(%hydroxyethyl)-thiophene were obtained, at 165' C. and a pressure of 120 * 5 mm., 200 grams of crude ZvinyIthiophene, This was dissolved in chloroform, the water layer separated, and the chloroform solution dried over anhydrous caIcium chloride. The dried product was distilled through a 6-inch helix-packed column, and 115.5 grams (53%) of Zvinylthiophene were obtained; b.p. 75" C. at 75 mm.; ny 1.5733; di0 1.037; molecular refraction calculated 34.28, found 35.00. Analysis: Calculated for C6H6S, c 65.45, H 5.45; found C 65.28, H 5.36. Microanalyses were carried out by Howard Clark of the Illinois State Geological Survey. Kuhn and Dann

Benzoyl, anisoyl, veratroyl, p‐bromobenzoyl, p‐phenylbenzoyl, p‐benzoylbenzoyl, p‐methylsulfonylbenzoyl, p(N,N‐dimethylsulfonamido)‐benzoyl and ‐naphthoyl disulfides are promoters of the emulsion copolymerization of butadiene and styrene, but exhibit little effect on the polymer properties. Furoyl, phenyl, p‐chlorophenyl and p‐bromophenyl disulfides are neither promoters nor modifiers.

Benzoyl disulfide product: Benzoyl disulfide