Boiling point approximate, under reduced pressure

The first step involves the preparation of 1 -(3-isobutoxy-2-chloro)propyl pyrrolidine as an intermediate. 345 ml of thionyl chloride dissolved in 345 ml of chloroform are added, drop by drop, to 275 g of 1 -(3-isobutoxy-2-hydroxy)propyl pyrrolidine dissolved in 350 ml of chloroform, while maintaining the temperature at approximately 45°C. The reaction mixture is heated to reflux until gas is no longer evolved. The chloroform and the excess of thionyl chloride are removed under reduced pressure. The residue is poured on to 400 g of crushed ice. The reaction mixture is rendered alkaline with soda and the resulting mixture is extracted twice with 250 ml of diethyl ether. The combined ethereal extracts are dried over anhydrous sodium sulfate. After evaporation of the solvent the residue is distilled under reduced pressure. 220 g of product are obtained having the following properties boiling point = 96°C/3 mm, n074 = 1.4575. 

A solution of 21.3 g. (0.10 mole) of freshly distilled N,N-dimethyldodecylamine (Note 1), 9.6 g (0.10 mole) of 94% <-butyl hydroperoxide (Note 2), and 0.050 g. of vanadium oxyacetylacetonate (Note 3) in 27 g. (34 ml.) of Cbutyl alcohol is placed in a 250-ml. round-bottomed flask fitted with a. thermometer, a reflux condenser, and a heating mantle. The reaction mixture is heated to approximately 65-70°, at which point an exothermic reaction begins. The heating is discontinued until the vigorous exothermic reaction subsides (about 5 minutes) and then the reaction mixture is heated at reflux (the reaction mixture boils at 90°) for 25 minutes. After the resulting mixture has been cooled to room temperature, it is analyzed (Note 4) to establish the absence oft-butyl hydroperoxide, and then concentrated with a rotary evaporator (30-35° bath with 30-40 mm. pressure). The crude solid residue is triturated with 50 ml. of cold (0-5°), anhydrous diethyl ether and then filtered under conditions which prevent exposure of the residual amine oxide to atmospheric moisture (Note 5). The residual solid is washed with 50 ml. of cold (0-5°) anhydrous diethyl ether and then dried under reduced pressure to leave 12.9-15.5 g. of the crystalline amine oxide, m.p. 131-131.5°. Concentration of the mother liquors and trituration of the residual paste with 25 ml. of cold (0-5°) anhydrous diethyl ether separates another 4.9-3.4 g. of the amine oxide, m.]). 130-131°. The total yield of the crystalline amine oxide (Note 6) is 17.4-18.9 g. (76 83%). 

As the vacuum pump is turned on and the pressnre is rednced, the liquid will begin to boil because the vapor pressure of the liquid is greater than the external pressnre (approximately zero). The heat of vaporization is snpplied by the water, and thns the water cools. Soon the water loses sufficient heat to drop the temperatnre below the freezing point. Finally the ice snblimes under reduced pressure. 

Little difference exists between the two oils. On distillation at ordinary pressure the oil, which is very rich in esters, in both cases decomposes pai-tially, and a considerable quantity of free add distils over. According to Weber Annalen, 238, 89), formic and acetic adds are found in the distillate. Acetic acid is undoubtedly the chief add constituent of the esters, but the author is unable to confirm the presence of foimic acid. If it is present, it is only in faint traces. On distillation under reduced pressure the earlier fractions (the boiling-point rises gradually until 50 per cent, has distilled over) contain cineol, but only to the extent of 5 to 10 per cent, of the oil. This figure is the result of an approximate estimation by means of phosphoric acid. 

Lemma.—The boiling-points under atmospheric pressure are approximately reduced temperatures ( = f) for all substances (Guldberg, 1890). 

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