Autocatalysis in Aromatic Alkylations. The Reaction of Phenols with Triphenylmethyl Chloride¹

Abstract

resulting mixture was refluxed for 13 minutes with stirring. After dilution with water, separation and drying over anhydrous magnesium sulfate, the product was distilled at 75-76' at 1 mm. (rep0rted~980.5" a t 0.8 mm.) yielding 25.1 g. (72%) of colorless p-bromostyrene oxide, m.p. 27.1' (re-ported18 26').p-Bromostyrene oxide (26.9 g.) reduced with 3.0 g. (4!0%) of lithium borohydride, gave an 83% yield of a mixture containing 20.4 g. (91%) of a fraction distilling a t 86-92" a t 1 mm. [largely l-(4-bromophenyl)-ethanolz0~ and 2.0 g. (9%) of 2-(4-bromophenyl)-ethanol, b.p. 104 a t 1 mm. (reportedz1 b.p. 147' a t 10 mm., m.p. 36-38").The product of a duplicate reduction of P-bromostyrene oxide, obtained in 66% yield, was analyzed by infrared absorption. Comparison of the maxima at 2950, 2930, 1595, 1200, 1110, 900 and 750 waves cm.-I with synthetic mixtures of the two isomeric alcohols, indicated a composition of 84% of the secondary alcohol and 16% of the primary.1-(4-Br01nophenyl)-ethanol (b.p. 98-102.5" at 2 mm.) was prepared independently in 68% yield by sodium borohydride reduction of p-bromoacetophenone in aqueous methanol. The phenylurethan melted at 103.6-104.0" (reportedz0 103-104'). 2-(4-Bromophenyl)-ethanol (b.p. 138' a t 9 mm.) was prepared in low yield by the aluminuni chloride-catalyzed bromination of 2-phenylethanol. The phenylurethan melted at 127.&139.0° (reportedz1 126').The phenylurethan prepared from the 1-(4-bromophenyl)ethanol fraction of the p-brotnostyrene oxide reduction product melted a t 102.1-102.8" and did not depress the m.p. of an authentic sample of the 1-(4-bromophenyl)ethanol phenylurethan. The urethan prepared from the isomeric fraction melted at 129.2-129.7' and did not depress the m.p. of an authentic sample of the urethan of 2-(4-bromophenyl) -ethanol.Lithium Borohvdride Reduction of 0-Nitrostyrene Oxide.-p-Nitrostyren& oxide was prepared from commercial fitiitrophenacyl bromide by the procedure used for p-broniostyrene oxide. The yield of product twice recrystallized from ethanol was 55%; m.p. 84.2-85.4' (reportedza 85-86"), A solution of 14.8 g. of P-nitrostyrene oxide in ether, reduced by 4.0 g. (800%) of lithium borohydride, gave upon dis-(19) T. Bergkvist, Pdensk Kern Tid., 59, 20: (1047); C. A , , 42, ( 2 0 ) R. Quelet, Uiiil. S O T . chi^., [ i ] 45, 73 (192'!l), reportcd h.p. l.'lOo (21) T. 1%'. J. T a y l o r and P. SI. Hotsoii, J . Cheirr. Soc., 191 (193C). 2981 (1948). a t 12' m m .FRANK A. CASSIS VOl. 76 tillation 9.4 g. (63%) of an oil, b.p. 134-142' a t 2 mm., which partially solidified upon standing, and 4.3 g. (29%) of a tarry residue. The mixture was not quantitatively separable by fractional distillation. Infrared analyses of this and a duplicate product fix the composition a t 62% 2-(4-nitrophenyl)-ethanol and 38% 1-(4-nitrophenyl)-ethanol, by comparison with synthetic mixtures, of the absorption a t 2930, 1200, 1090, 1035, 900 and 840 waves l-(4-hTitrophenyl) -ethanol, prepared independently by the sodium borohydride reduction of P-nitroacetophenone, 2z boil...

Acid-base behavior in aprotic organic solvents

“…Hart and Cassis, who studied this reaction and the corresponding reaction of o-cresol with trityl chloride, yielding p-trityl-o-cresol, concluded that the most likely role of HCl is in facilitating the ionization of trityl chloride, as represented by the following equation [505]:…”

Solvolytic Displacement Reactions At Saturated Carbon Atoms

“…The reaction of phenol with triphenylmethyl chloride in an inert solvent yields the p-alkylated phenol and can be catalyzed by hydrogen chloride (309). Alkylation of phenols by a-phenylethyl chloride may be similarly accomplished to give ortho or para substitution or a mixture depending on the structure of the phenol used.…”

Acid-catalyzed solvolysis: unusually rapid solvolysis of 3-fluoronortricyclene in CD3COOD – 0.1 M D2SO4

“…Although the rate of solvolysis of alkyl chlorides is usually not affected by the addition of acid (7,8) exceptions have been noted in the case of chloroethers (9, 10) and the reaction of trityl chloride with phenol (11). With respect to alkyl fluorides, however, several workers (3,6,(12)(13)(14) have discovered enhanced rates in the presence of acid.…”