Detail of "98-85-1"

Reference

Are there covalent active species in the polymerization of styrene initiated by trifluoromethanesulfonic acid?

Are there covalent active species in the polymerization of styrene initiated by trifluoromethanesulfonic acid?. Matyjaszewski, Krzysztof; Sigwalt, Pierre (Lab. Chim. Macromol., Univ. Pierre et Marie Curie, Paris 75230, Fr.). Makromol. Chem., 187(10), 2299-316 (English) 1986. CODEN: MACEAK. ISSN: 0025-116X. DOCUMENT TYPE: Journal CA Section: 35 (Chemistry of Synthetic High Polymers) Polymn. of styrene [100-42-5] by HClO4 and F3CSO3H [1493-13-6] was assumed to proceed via a pseudo-cationic mechanism, but for the latter system the trifluoromethanesulfonate ester was not stable. Attempts to observe the model 1-phenylethyl ester were unsuccessful even at -78°. In the reaction between 1-phenylethyl bromide [585-71-7] and F3CSO3Ag [2923-28-6] a very rapid alkylation of the arom. rings occurred. In the reaction between 1-phenylethanol [98-85-1] and (F3CSO2)2O [358-23-6] a very rapid reaction between the intermediate ester (or ion) and the alc. led to the formation of the corresponding ether [93-96-9]. A reaction carried out with the optically active alc. indicated that ￡4% of the intermediate species might have reacted with the alc. as ester before racemization (i.e. ionization). The macromol. ester did not seem to be much more stable and in 19F NMR spectra only the acid was obsd. An attempt at the formation of a block copolymer with N-tert-butylaziridine gave zero or very low yields, contrarily to results previously obsd. with HClO4. An anal. of some former results on polymn. kinetics and of the new data obtained showed no real evidence in favor of the pseudo-cationic polymn. of styrene in CH2Cl2, initiated by CF3SO3H. The various data could be explained more satisfactorily by a more classical ionic mechanism. Triflic acid could reversibly protonate olefins due to the affinity of the triflate anion being higher for a proton than for a secondary or tertiary carbon atom; this was sufficient to explain the extremely low concn. of ionic species.

Dehydration of

Dehydration of .alpha.-methylbenzyl alcohols to form monovinylidene aromatic monomers. Lamson, Junior J.; Hall, Richard H.; Stroiwas, Edward; Yats, Larry D. (Dow Chemical Co., USA). U.S. US 4049736 20 Sep 1977, 6 pp. (English). (United States of America). CODEN: USXXAM. CLASS: IC: C07C015-00. NCL: 260669000QZ. APPLICATION: US 70-39889 22 May 1970. DOCUMENT TYPE: Patent CA Section: 35 (Synthetic High Polymers) .alpha.-Methylbenzyl alcs. were converted in high yield and purity to styrene (I) [100-42-5] and substituted styrenes by contacting the alc. in the vapor phase with silica gel and steam. Thus, a mixt. of .alpha.-methylbenzyl alc. [98-85-1] and 50 parts toluene were preheated to 300.degree., mixed with 100 parts steam at 300.degree., passed downward through a glass column contg. an upper layer of SiC preheated to 350.degree. and a 6-in. lower layer of silica gel, collected and distd. to give >95% I contg. <0.5 mol% ethylbenzene.