Bromo-o-xylene

CH3Br + Mg CHaMgBr CHgMgBr + CH2=CHCHO ------ CH2=CHCH—OMgBr 

Kohler, Am. Chem. J., 38, 525 (1907), reports the preparation of 122 g. of l-pentene-3-ol, b.p. 114-116°, from 100 g. (1.8 moles) of acrolein and ethylmagnesium bromide by a similar procedure. 

Checked by N. L. Drake, Wilkins Reeve, and John Sterling, Jr. 

Essentially the same yield results if only one of the catalysts (iron or iodine) is used. 

In experiments in which the temperature of the reaction mixture was allowed to rise as high as +10°, the submitters noted a slight increase in the amount of dibromo-o-xylene formed. 

A dilute sodium bisulfite solution may be used instead of the alkali in this washing. 

Near the end of the steam distillation a white waxy product begins to collect in the condenser. This is apparently a di-bromo-o-xylene. 

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A mixture of 200 g. (1.08 moles) of 4-bromo-o-xylene [Org. Syntheses, 28, 22 (1948)], 14 g. of copper wire, and 600 ml. of concentrated ammonium hydroxide solution containing 12 g. of cuprous chloride is placed in a bomb and heated to 195° for 14 hours with agitation. The pressure is 900-1000 lb. The organic layer is separated from the resulting reaction mixture, and to the organic layer is added 40 ml. of 40% aqueous sodium hydroxide solution. The mixture is steam-distilled to remove the 3,4-dimethylaniline which is separated from the distillate and further purified by solution in 500 ml. of 8% aqueous hydrochloric acid, extraction with ether, and reprecipitation from the aqueous solution with 160 ml. of 40% alkali. The resulting alkaline solution is steam-distilled. The amine is separated from the distillate, dried, and distilled under vacuum. The product boils at 116-118°/22-25 mm., and the yield is 103 g. (79%). 

The crude product contains a small amount of unchanged 4-bromo-o-xylene which is removed by the ether extraction. 

Displacement of aromatic halogen. With both cuprous chloride and copper as catalyst 4-bromo-o-xylene can be converted into the corresponding amine. The... 

Catalysis. A procedure for the preparation of 4-bromo-o-xylene calls for addition of bromine over 3 hrs. to a stirred mixture of 500 g. of o-xylene with 12 g. of iron filings and a crystal of iodine. A note states that neither catalyst suffices by itself. 

The procedure given was developed by Ghigi2 from an earlier preparation by Jacobsen.3 4-Bromo-o-xylene has also been prepared from 3,4-dimethylaniline by the Sandmeyer reaction.4,5... 

Auwors, Ercklentz, Ann., 1898, 302,113. 5>Bromo-o-4-xylidine 5-Bromo-4-amino-o-xylene)... 

Benzoic m-Toluic (Benzoic acid, 3-methyl-] p-Toluic [Benzoic acid, 4-methyl-J 3,5-Dimcthylbcnzoic [Benzoic acid, 3,5-dimcthyl-] p-Chlorobenzoic [Benzoic acid, 4-chloro-] p-Bromobenzoic [Benzoic acid, 4-bromo-J Phthalic [ 1,2-Bcnzcncdicarboxylic acid] Toluene [Benzene, methyl-] (78) m-Xylene [Benzene, 1,3-dimethyl-] (82) />-Xylene [Benzene, 1,4-dimethyl-] (74) Mesitylene [Benzene, 1,3,5-trimethyl-] (82) p-Chlorotolueno [Benzene, l-ehloro-4-methyl-] (94) p-Bromotolucnc [Benzene, l-bromo-4-methyl-] (94) o-Xylene [Benzene, 1,2-dimethyl-] (64)... 

Tetramethyl-dipbenylamine, thick oil, bp — partially decomp 340—45° prepd from asym o-xylene, bromo-Zn-ammonia Amm bromide heated in a tube at 300-310° (Ref 2)... 

Other additions to the double bond of compounds in this series have not been studied extensively, but reports now indicate that several such additions can be accomplished efficiently. Nitryl iodide is, however, not added92 to the double bond of compound 45, but bromination in methanol, in the presence of barium carbonate, gives crystalline methyl 4,6-0-benzylidene-2,3-dibromo-2,3-dideoxy-a-D-altropyranoside in 70% yield.93 On treatment with potassium tert-butoxide in refluxing xylene, this compound undergoes elimination of the elements of hydrogen bromide to give methyl 4,6-O-benzylidene-2-bromo-2,3-dideoxy-a-D-t/ireo-hex-3-enopyranoside (46, R = Br) in 90% yield. Likewise, compound 45 reacts with acetyl hypobromite to give methyl 3-0-acetyl-4,6-0-benzylidene-2-bromo-2-deoxy-a-D-glu-... 

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