Drying agent white

A mixture of 20 g of 1 -bromo-3,5-dimethyladamantane, 75 ml of acetonitrile, and 150 ml of concentrated sulfuric acid was allowed to react overnight at ambient room temperature. The red reaction product mixture was poured over crushed ice, and the white solid which precipitated was taken up in benzene and the benzene solution dried over sodium hydroxide pellets. The benzene solution was filtered from the drying agent and evaporated to dryness in vacuo to yield 1 B.2 g of product having a melting point of about 97°C and identified by infrared spectrum as 1-acetamido-3,5-dimethvladamantane. 

When phosphorus burns in an ample supply of air, it forms phosphorus(V) oxide, P4O]0 (5). This white solid reacts so vigorously with water that it is widely used in the laboratory as a drying agent. Phosphorus(V) oxide is the anhydride of phosphoric acid, H3P04 (6) ... 

The pentane extract is dried over 10 g. of anhydrous potassium carbonate. After removal of the drying agent by filtration, the j)entane is slowly removed from the product by distillation through a 20-cm. Hempel column packed with glass helices (Note 6). When the pentane is removed, a white crystalline residue remains which weighs 78-83 g. (88-94% yield based on the hydrogenated Diels-Alder adduct). This 2,3-diazabicyclo 2.2.1 hept-2-ene melts at 98.0-99.5° (Note 7). 

The physical constants of several other imines prepared by a similar procedure are shown in Table X. The aldimines listed in the Table can be obtained only if certain precautions are strictly observed [4b]. The method of Emerson, Hess, and Uhle [4c] could not be extended satisfactorily and the method described in Preparation 2-2 is a modification of the one described by Chancel [4d] for propylidenepropylamine. The reaction is best carried out by adding the aldehyde to the amine, without a solvent, at 0°C. When the order of addition is reversed, the yields are much lower. Potassium hydroxide is added at the end in order to remove the water formed during the reaction. The use of other drying agents such as potassium carbonate or magnesium sulfate failed to yield aldimines on distillation. The aldimines should always be distilled from fresh potassium hydroxide to yield water-white products. The aldimines are unstable and should be used within a few hours after their distillation otherwise polymeric products are obtained. 

A well-stirred solution of 0.09 g l-(2,5-dimethoxy-4-(2-hydroxy-ethyl)phenyl)-2-(2,2,2-trifluoroacetamido)propane in 15 mL CH,C12 was cooled to -78 °C and treated with 0.05 g diethylaminosulfur trifluoride (DAST) added dropwise. The pale yellow reaction solution was stirred an additional 5 min and then brought up to room temperature and stirred for 1 h. There was then added (cautiously) 3 mL H20 followed by additional CH2C12. The phases were separated, the organic phase washed with H20, dried with anhydrous Na.SO, and, after filtering off the drying agent, stripped of solvent under vacuum. There was thus obtained 0.088 g of l-[2,5-dimethoxy-4-(2-fluoroethyl)phenyl]-2-(2,2,2-trifluoro-acetamido)propane as a white solid with a mp of 102-104 °C. 

HC1. The aqueous extracts were pooled, washed with CH2CI2, and made basic by the addition of 25% NaOH. The precipitate that formed was extracted into several small portions of CH2CI2 which were pooled and dried with anhydrous Na2S04. After removal of the drying agent, the solvent was removed under vacuum. To the residue there was added a 1.0 M solution of HC1 in anhydrous Et20 until the mixture was neutral, as determined by external, damp pH paper. The resulting solid was removed by filtration and twice recrystallized from aMeOH/acetone mixed solvent. There was thus obtained N,N-diethyl-2-methyltryptamine hydrochloride (2-Me-DET) as white crystals with a mp 214-216 °C. 

Filter off the drying agent and evaporate the solution using a rotary evaporator to give the product 81 as an off-white solid, m.p. 233-234°C, 19.95 g (87%). 

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