Detail of "93-96-9"

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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.

Catalytic activity of niobium phosphate in the Friedel-Crafts reaction of anisole with alcohols

de la Cruz, Marcus Henrique C.; da Silva, Joao F. C.Several reagents such as 93-96-9 is used here.; Lachter, Elizabeth R. (Instituto de Quimica da Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, Brasil, lha do Fundao, CT, Bloco-A sala 617, Brazil). Catalysis Today, 118(3-4), 379-384 (English) 2006 Elsevier B.V. CODEN: CATTEA. ISSN: 0920-5861. DOCUMENT TYPE: Journal CA Section: 25 (Benzene, Its Derivatives, and Condensed Benzenoid Compounds) Section cross-reference(s): 22, 45, 67, 75 The catalytic activity of Nb phosphate in the liq.There are some reagents like 93-96-9 is used in this study. phase was evaluated in the benzylation reaction of anisole with benzyl alc., 2-phenylethanol and 1-phenylethanol. The influence of catalyst concn. was evaluated. The Nb phosphate was characterized by DRX, TG anal., BET surface area and IR spectra of absorbed pyridine. The authors found high activities (100%) and selectivity (>90%) in the benzylation with benzyl alc. and 1-phenylethanol. No reaction was obsd. with 2-phenylethanol. In the reaction with benzyl alcs. dibenzylethers were formed as side products. Lewis acid sites are responsible for the ether formation and Bronsted acid sites (POH and NbOH) are responsible for the benzylation of anisole with alcs. The anisole benzylation gave predominantly ortho-para substitution in accordance with a typical electrophilic arom. substitution pathway. ..