Benzene, dry, thiophene free

Dry ethyl ether and dry, thiophene-free benzene were prepared by the submitters according to procedures presented in ref. 2. 

A. Ethyl 3-methylcoumarilate. Dry sodium phenolate (116 g., 1 mole) (Note 1) and 1 1. of dry thiophene-free benzene (Note 2) arc placed in a 2-1. three-necked flask fitted with mechanical stirrer, dropping funnel, and reflux condenser with drying tube. The suspension is heated to the boiling point on the steam bath, heating is moderated, and 165 g. (1 mole) of ethyl a-chloroaceto-acetate (Note 3) is added with stirring through the dropping... 

The toluene (Merck reagent grade) was kept dry by storage over sodium wire. Dry thiophene-free benzene may be used instead but is less convenient because it freezes when added to the liquid ammonia solution. 

Maleic anhydride was crystallized from sodium dried, thiophene-free benzene. The bisisobutyronitrile was crystallized from a mixed solvent containing equal volumes of benzene and toluene. The liquid monomers were purified by distillation under reduced pressure. Freshly distilled solvents were used. 

Method B. Place a solution of 2.5 g of pure 1,4-naphthoquinone (1) in 50 ml of dry thiophene-free benzene in a 50-ml round-bottomed flask and pass a slow stream of dry nitrogen through the solution for 5 minutes. Insert a lightly greased stopper in the flask taking care that the solution does not penetrate the joint. Place the flask in a sunny position - if situated in the open air wrap some aluminium foil around the stopper to prevent the possibility of rainwater seeping through the joint into the reaction mixture. Solid slowly... 

Preparation of isobutyrophenone In a 12 liter, 3-necked flask, 1,280 grams of aluminum chloride was covered with 2,000 cc of dry thiophene-free benzene and a solution of 919 grams of isobutyryl chloride, (BP 92°-94°C) in 1 liter of benzene was added slowly with stirring. After heating for 3 hours at reflux, the solution was cooled and poured over a mixture of 1 liter of concentrated hydrochloric acid and 5 kg of ice. The benzene layer was separated, the aqueous layer extracted with benzene, and the combined benzene solutions were washed, dried and concentrated in vacuo. The residue was distilled rapidly to give 1,051 grams of isobutyrophenone, boiling at 81°-89°C at 1 mm, yield 83.4%. 

B) Methylhydr azine Sulfate.—Two himdred grams (0.96 mole) of benzalazine, 350 cc. of dry, thiophene-free benzene, and TOO cc. (133 g., r.05 moles) of dimethyl sulfate (Note 3) are mixed in a 3-I. round-bottomed flask, provided with a reflux condenser... 

A solution of 205 g. (1.75 moles) of 2-diethylaminoethyI alcohol in 500 ml. of dry thiophene-free benzene is cooled in an ice-salt bath... 

Phenylmagnesium bromide is prepared in the usual manner Org, Syntheses Coll. Vol. 1, 550 (1941)] from 52 g. (0.33 mole) of bromo-benzene and 7.2 g. (0.30 gram atom) of magnesium. To the solution of the Grignard reagent in ether is added a solution of 38.8 g. (0.2 mole) of Enthrone [Org. Syntheses Coll. Vol. 1, 60 (1941)] in dry thiophene-free benzene. Excess ice and dilute hydrochloric acid are added, the ether layer is separated, and the aqueous layer is extracted with ether. The combined ethereal solutions are washed with 12% aqueous alkali solution and water. The ether is evaporated, and the residue is steam-distilled. The residue from the steam-distillation vessel is taken up in ether, and the ether is evaporated. The residual syrup is heated with a mixture of 12% aqueous sodium hydroxide and 10 g. of sodium hydrosulfite. The mixture is cooled and diluted with ether the alkaline aqueous layer is separated and discarded the ethereal layer is washed thoroughly with water and the ether is evaporated. The residual 9-phenylanthracene is reciystallized from acetic acid to give 36 g. (71%) of product, m.p. 152-153°. 

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