Ethanol, 2-bromo

Ethyl (C2) Comparison Group 2-bromo-Ethanol C2HsBrO 540-51-2 133 181 —... 

The setup used is the one pictured in fig. 9 except there is no ice bath tray. In the reaction flask is stirred a solution of 30g NaNa in 400mL ethanol (Everclear is perfectly ok) or propanol (chemist s choice) and 80mL dH20. 120g of bromo-safrole or 80g... 

In the flask were placed 40 ml of ethanol, 10 ml of water, 12 g of finely powdered CuCN and 0.40 mol of 3-bromo-l-butyne (compare VIII-2, Exp. 3). The mixture was warmed to 55°C and a solution of 26 g of KCN in 60 ml of water was added drop-wise or in small portions care was taken that complete dissolution of the copper cyanide did not occur (note 2). The temperature of the mixture was maintained close to 60°C throughout the period of addition. The conversion was terminated... 

Diethyl oxalate (29.2 g, 0.20mol) and 4-bromo-2-nitrotoluene (21.6 g, O.lOmol) were added to a cooled solution of sodium cthoxide prepared from sodium (4.6 g, 0.20 mol) and ethanol (90 ml). The mixture was stirred overnight and then refluxed for 10 min. Water (30 ml) was added and the solution refluxed for 2h to effect hydrolysis of the pyruvate ester. The solution was cooled and concentrated in vacuo. The precipitate was washed with ether and dried. The salt was dissolved in water (300 ml) and acidified with cone. HCl. The precipitate was collected, washed with water, dried and recrystallizcd from hexane-EtOAc to give 15.2 g of product. 

Bromo-2-nitrophenylacetic acid (26 g, 0.10 mol) was dissolved in a mixture of 50% HjSO (400 ml) and ethanol (600 ml) and heated to 90°C. Over a period of 1 h, zinc dust (26.2 g, 0.40 mol) was added. slowly and then heating was continued for 2 h. The excess ethanol was removed by distillation. The solution was cooled and filtered. The filtrate was extracted with EtOAc. The filtered product and extract were combined, washed with 5% NaCOj and brine and then dried (MgSO ). The solvent was removed in vacuo and the residue recrystallized from methanol to give 20.5 g (97% yield) of the oxindole. 

FIGURE 5 12 The El mechanism for the dehydrohalogenation of 2 bromo 2 methylbutane in ethanol... 

A single organic product was obtained when 1 bromo 3 chloro propane was allowed to react with one molar equivalent of sodium cyanide in aqueous ethanol What was this product j... 

Tertiary alkyl halides are so sterically hindered to nucleophilic attack that the pres ence of any anionic Lewis base favors elimination Usually substitution predominates over elimination m tertiary alkyl halides only when anionic Lewis bases are absent In the solvolysis of the tertiary bromide 2 bromo 2 methylbutane for example the ratio of substitution to elimination is 64 36 m pure ethanol but falls to 1 99 m the presence of 2 M sodium ethoxide... 

The ratio of elimination to substitution is exactly the same (26% elimination) for 2 bromo 2 methylbutane and 2 lodo 2 methylbutane in 80% ethanol/20% water at 25°C... 

A variety of conditions has been used to prepare oxiranes from trans-hxomo-hydrins. In general, bromohydrins are heated in a solution of 5-10% methanolic potassium hydroxide for 30 min to 8 hr. Longer reflux times are required for bromohydrins which are not anti-coplanar, e.g., diequatorial bromohydrins. A 5 % solution of potassium acetate in boiling ethanol can be used to cyclize steroidal bromohydrins containing base sensitive groups. The use of 1.1 equivalents of sodium methoxide per equivalent of steroid in methanol solution is especially recommended for 9a-bromo-l lj5-hydroxy steroids. 

To a solution of 2a-bromo-5a-cholestan-3-one (7.1 g, 15.2 mmol) in 175 ml dry acetone is added dropwise a solution of potassium ethyl xanthate (2.6 g, 16.2 mmol) in 90 ml acetone. The reaction mixture is stirred at 20° for 12 hr and then evaporated to dryness under vacuum. The resulting solid is treated with 100 ml hexane to dissolve the organic material and the inorganic salts are removed by filtration. The hexane filtrate is concentrated under vacuum and the resulting yellow solid ca. 7.5 g) is crystallized from chloroform-ethanol to give the xanthate (137) as white needles, ca. 5 g mp 114-115°. 

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