A. 2-Methyl-2-nitropropane. To a well-stirred suspension of 650 g. (4.11 moles) of potassium permanganate in 3 l. of water, contained in a 5-l., three-necked flask fitted with a reflux condenser, a mechanical stirrer, a thermometer, and a 250-ml. dropping funnel, is added, dropwise and with stirring over a 10- minute period, 100 g. (1.37 moles) of tert-butylamine (Note 1). When the addition is complete, the reaction mixture is heated to 55° over a period of approximately 2 hours, and maintained at 55° with continuous stirring for 3 hours. The dropping funnel and reflux condenser are replaced with a stopper and a still head fitted for steam distillation, and the product is steam distilled from the reaction mixture (Note 2). The liquid product is separated from the denser water layer, diluted with 250 ml. of diethyl ether, and washed successively with two 50-ml. portions of 2 M hydrochloric acid and 50 ml. of water. After the ethereal solution has been dried over anhydrous magnesium sulfate, the solution is fractionally distilled at atmospheric pressure, removing the ether. The residual crude product (Note 3) totals 106–128 g. and is sufficiently pure for use in the next step. In a typical run, distillation of 124 g. of the crude product affords 110 g. (78%) of the pure 2-methyl-2-nitropropane as a colorless liquid, b.p. 127–128°, n²⁵D 1.3992, which slowly solidifies on standing to a waxy solid, m.p. 25–26° (Note 4).

B. N-tert-Butylhydroxylamine. Caution! Since hydrogen may be liberated during the reduction with aluminum amalgam, the reaction should be conducted in a hood. Also, the aluminum amalgam may be pyrophoric. Consequently, it should be used immediately and not allowed to become dry.

Aluminum foil (30 g. or 1.1 g.-atoms, thickness 0.002–0.003 cm.) is cut into strips 5 × 25 cm., and each strip is rolled into a cylinder about 1 cm. in diameter. Each of the aluminum foil cylinders is amalgamated by immersing it in a solution of 8.0 g. (0.030 mole) of mercury(II) chloride in 400 ml. of water for 15 seconds. Each amalgamated cylinder is then rinsed successively in ethanol and ether, and added to a mixture of 1.5 l. of ether and 15 ml. of water (Note 5) contained in a 3-l., three-necked flask fitted with a dropping funnel, a mechanical stirrer, and two efficient reflux condensers in series. The reaction mixture is stirred vigorously, and 60 g. (0.58 mole) of 2-methyl-2-nitropropane is added dropwise at a rate such that the ether refluxes briskly. The reaction usually exhibits a 5- to 7-minute induction period, after which a vigorous reaction occurs and cooling with an ice bath is necessary. After addition of the nitro compound is complete, the reaction mixture is stirred for an additional 30 minutes. The stirrer is then stopped and the gelatinous precipitate is allowed to settle. The colorless reaction solution is decanted through a glass wool plug into a 2-l. separatory funnel and washed with two 250-ml. portions of 2 M aqueous sodium hydroxide (Note 6). The precipitate in the reaction flask is washed with two 500-ml. portions of ether, and these washings are combined and washed with the aqueous sodium hydroxide solution (Note 6). The combined ethereal solutions are dried over anhydrous sodium sulfate and concentrated with a rotary evaporator. The residual crystalline solid is dried under reduced pressure (10–15 mm.) at room temperature, leaving 33.7–38.7 g. (65–75%) of the crude hydroxylamine product, m.p. 59–60°, which is sufficiently pure for use in the next step. The crude product may be recrystallized from pentane, yielding the pure N-tert-butylhydroxylamine as white plates, m.p. 64–65° (Note 7).

C. 2-Methyl-2-nitrosopropane. A solution of sodium hypobromite is prepared by adding, dropwise and with stirring over a 5-minute period, 57.5 g. (18.5 ml., 0.360 mole) of bromine to a solution of 36.0 g. (0.900 mole) of sodium hydroxide in 225 ml. of water. The resulting yellow solution, contained in a 1-l., three-necked flask fitted with a mechanical stirrer, a thermometer, and an acetone–dry ice cooling bath, is cooled to −20°. A suspension of 26.7 g. (0.300 mole) of N-tert-butylhydroxylamine in 50 ml. of water is added to the reaction flask, with continuous stirring, as rapidly as possible without allowing the temperature of the reaction mixture to exceed 0°. The reaction solution is again cooled to −20° before the cooling bath is removed and the mixture is stirred for 4 hours while the reaction mixture warms to room temperature. The solid product, the nitroso dimer which has separated, is collected on a sintered glass funnel, pulverized, and washed with 1 l. of water (Note 8). The residual solid is dried at room temperature under reduced pressure (10–15 mm.), leaving 19.6–22.2 g. (75–85%) of the 2-methyl-2-nitrosopropane dimer, m.p. 80–81° (Note 9). The product is sufficiently pure to be stored (Note 10) for use as a free radical trapping reagent.