Alkoxy- and Aryloxystyrenes¹

Abstract

The present paper discusses the methods of preparation of a number of substituted styrenes containing methyl and phenyl ether groups.The chloroethylation reaction discovered by Quelet and Ducasse, followed by dehydrohalogenation of the resulting 1-chloroethyl derivative, is a feasible method for a limited number of styrenes, although yields are reduced by a secondary reaction during chloroethylation, represented as follows in the case of anisole CHaOC6Hj + CH~OC6H~CHClCH~ 4 ( C H J O C~H~)~C H C H~ + HCl I t seemed that an optimum period of reaction might niininiize the formation of this by-product, and experiments with anisole (Table I) have shown this to be true. Extending the reaction time past one hour under the conditions used greatly increased the yield of ltl-di-(4-methoxyph.eny1)-ethane, although the yield in grams of 4-inethoxystyrene was substantially the same in all runs of greater than one hour duration. TABLE I CIILORORTHYLATIC" O F -4NISOLE Yield of 1,lI<eaction Yield of cti-(methoxytime 4-MethoxystyreuP phenyl)-ethane, at 5 O , hr. K. ' Sh % 1.25 fi2.0 32.8 43 I 4 1.75 8 5 . 5 3 2 . 1 50.2 3 . 5 61.0 2 3 . 8 72.9 4 . 0 6 3 . 5 26.3 69.7a Yields were based on anisole which was not recovered. Fractions boiling lower than 4methoxystyrene and having ~* O D 1.517-1.544 were assumed to be recovered anisole.These fractions contained some 4-methoxystyrene which was recoverable by fractional distillation.All of the high-boiling material remaining after distillation of 4-inethoxystyrene was assumed t o be l,l-di-(4-methoxyphenyl)-ethane, in accordance with the findings of Quelet (ref. 2b).Other styrenes prepared by chloroethylation in yields of 3449% were 4-methoxy-3-methylstyrene, 2-methoxy-5-methylstyrene and 5 4 0 -propyl-4-methoxy-2-methylstyrene. In all cases the recovery of unchanged starting material was seriously diminished by the formation of diarylethaue by-rotluc ts.Chlurc,ethylatiori apprars to be more limited in scope than chloromethylation. A single halogen atom on the aromatic nucleus caused sufEicient deactivation to prevent reaction. Attempts to chloroethylatc 0-, 111-and p-chloroanisole, m-and ( I ) Tile work rlewribed ill thi.; mnnusrript was carried out under the sponsorship of the Onice ul I<ubber Reserve, Reconstruction Finance Corporatiuu, in counectiou with the Guverument Synthetic Rubber Pri)&pmi. (2) ,(a) Quclet anit I),icas~c, ( ' U J~I~. r e d . , 398, 1317 (1939); (L) Quelct, Utcil. ,I,,. ' I ! l I I l . , ( 5 ) 7, 196, w.5 (1'J.iO).9-bromoanisole, dimethylaniline, N-methylacetanilide and 1,4-dimethoxybenzene were unsuccessful.The preparation of 3,Q-dimethoxystyrene, attempted by chloroethylation of veratrole, gave yields of only 6%, and a more suitable synthesis was sought in the addition of methylmagnesium iodide to veratraldehyde, followed by dehydration of the resulting 1-(3,4-dimethoxyphenyl)-ethanol. The latter compound was best dehydrated by slow distillation under reduced pressure, which gave much better results than heating in the presence of iodine, activated alumina, p...

Formation of Styrenes - By Pyrolysis of Aromatic or Heterocyclic Aldehyde-Aliphatic Acid Anhydride Mixtures over Morden Bentonite

“…This trend is also evident with cinnamic acid yields (7,2,13,15,20) reported for the Perkin reaction (Table IV). Evidently, in the chlorosubstituted aldehydes the electron-acceptor halogen atom facilitates reaction by rendering the carbon atom of the carbonyl group more electrophilic, while in the methyl derivatives the electrondonor capacity of the methyl group exercises the opposite effect.…”

“…The magnitude of these side reactions becomes more marked with rise in temperature, and at 600°G. ethylbenzene formation constitutes the dominant reaction, its appearance being caused by a disproportionation reaction involving side-chain hydrogenation of the vinylbenzene molecule (7,(76)(77)(78). In extent of both aldehyde and styrene recovery, the process is most economical at 400°C.…”

The Reaction between Grignard Reagents and the Oxirane Ring.

“…Substituted aryl Grignard reagents have been used to prepare substituted phenylethanols. Thus, bromoanisoles (1,26,70,103,152,189), bromomethylanisoles (1, 26,189), bromophenetoles, bromotolyl butyl ether (26), phenoxybromobenzene (70), and m-(t rifluoromethyl)bromobenzene (197) have been converted into Grignard reagents and caused to react with ethylene oxide to produce the corresponding substituted phenylethanols.…”

The Preparation of Substituted Styrenes by Methods Not Involving Hydrocarbon Cracking.

“…chí0hoh<3cooC!h, + H,o -3^g:c-. ch2=ch<(3cooh /3-Phenethyl alcohols also are dehydrated very smoothly and in general give purer products than do the a-isomers (57,121). This operation uniformly has been effected by distilling the alcohol from solid potassium hydroxide with a pot temperature of about 200°C., usually in a copper vessel.…”

“…methyl-a-phenethyl acetate only the alcohol was obtained. When vapors of p-phenoxy-a-phenethyl isopropyl ether were passed over alumina at 325-450°C., p-phenoxystyrene was obtained (57). Distillation was sufficient to convert 3,4-methylenedioxy-a-phenethyI ether to 3,4-methyIenedioxystyrene (14).…”