Vacuum notes

A mixture of 0.10 mol of the acetylenic alcohol, 0.12 mol of triethylamine and 200 ml of dichloromethane (note 1) was cooled to -50°C. Methanesulfinyl chloride (0.12 mol) (for its preparation from CH3SSCH3, (08300)30 and chlorine, see Ref. 73) was added in 10 min at -40 to -50°0. A white precipitate was formed immediately. After the addition the cooling bath was removed and the temperature was allowed to rise to -20°0, then the mixture was vigorously shaken or stirred with 100 ml of water. The lower layer was separated off and the aqueous layer was extracted twice with 10-ml portions of CH2CI2. The combined solutions were dried over magnesium sulfate and concentrated in a water-pump vacuum (note 2). The yields of the products, which are pure enough (usually 96%) for further conversions, are normally almost quantitative. 

If the urethane is to be hydrolyzed immediately, there is no need to isolate it. Instead, after distillation of most of the ether and alcohol from the flask in which the urethane is formed, 700 ml. of concentrated hydrochloric acid is added, and the mixture is heated under reflux for 4 hours. The solution is then distilled from a steam bath under aspirator vacuum (Note 11), and the putrescine dihydrochloride is isolated as described above. The total yield is 55-57 g. (74-77%). 

The suction pressure required ai the vacuum pump (in absolute pressure) is the actual process equipment operating pressure minus the pressure loss between the process equipment and the source of the vacuum. Note that absolute pressures must be used for these determinations and not gauge pressures. Also keep in mind that tlie absolute pressure at the vacuum pump must always be a lower absolute pressure than tlie absolute pressure at the process. 

The combined filtrates containing benzonitrile oxide are transferred to a 1-1. round-bottomed flask, treated immediately with 13.9 g. (0.1 mole) of N-sulfinylaniline added in one portion, with swirling, and set aside protected from moisture, while the temperature reaches a maximum of 33-34° (usually IS minutes). The mixture is then heated to reflux, protected from moisture, in a temperature-controlled oil bath for 3-5 hours. Continuous evolution of sulfur dioxide takes place during this period at the end of which the mixture is cooled and evaporated under reduced pressure (Note 3) at 70-80° to remove the solvent. The residual dark brown liquid is transferred to a 50-ml., pear-shaped distilling flask (Note 13) and heated, protected from moisture, at 110° for 30 minutes to complete the decomposition. It is then cooled and distilled under high vacuum (Note 14). Unchanged N-sulfinylaniline (2.0-2.5 g.) distills over at 45-50° (0.1-0.2 mm.). A second fraction (1.2-1.5 g.) is collected until the temperature reaches 112° (Note 15) then diphenyl carbodiimide is collected at 114-117° (0.1-0.2 mm.) as a clear yellow liquid yield 10.5-10.8 g. (54-56%) (Note 16) 1.6355 ... 

Cerenkov radiation emission of blue hght by particles moving faster than light in a medinm other than the vacuum (note that in a medinm with refrachve index n, hght moves with speed v = cjn)... 

B. 2,5-Dimethylmandelic acid. A mixture prepared from 140 g. (0.5 mole) of 2,5-dimethylphenylhydroxymalonic ester and a cold solution of 140 g. of potassium hydroxide in 560 ml. of water in a 1-1. round-bottomed flask is warmed on a steam bath for 5 hours. The alkaline solution is cooled and extracted with one 100-ml. portion of ether to remove any material not soluble in alkali. The alkaline solution is acidified with 300 ml. of concentrated hydrochloric acid and then warmed on a steam bath and stirred for 2 hours (or until there is no further evidence that carbon dioxide is escaping). The mixture is cooled, the oily layer is extracted with ether, the ethereal solution is dried with anhydrous sodium sulfate, and the ether is distilled under partial vacuum (Note 3). The oily residue is crystallized from benzene. The yield of 2,5-dimethyImandelic acid melting at 116.5-117° is 55-63 g. (63-70%) (Note 4). 

The flask is now disconnected from the stirrer and column, and the contents distilled off as completely as possible on the steam bath under reduced pressure. The remaining solid is freed from residual moisture and hydrochloric acid by allowing a slow current of dry air to pass over it, while still heating on the steam balh and maintaining a partial vacuum (Note 3). It is then redissolved in distilled water, and the solution filtered with... 

A 500-mL, two-necked, round-bottomed flask equipped with a stirring bar and a rubber septum is charged with copper(l) cyanide (2.95 g, 33.0 mmol, Note 5). The flask is evacuated and gently flame-dried under vacuum (Note 6), then flushed with dr) argon. The process is repeated 3 times. Anhydrous tetrahydrofuran (33 mL) i injected and the resulting slurry is cooled to -78°C. At this time, the previously prepared solution of 2-lithiothiophene in tetrahydrofuran (at -20°C) is added via cannula to the stirring slurry. At the end of the addition, the acetone-dry ice bath is... 

C. Excess 1 is destroyed by adding 22 mL (0.3 mol) of freshly distilled propionaldehyde and stirring for 1 hr at room temperature. Liberated a-pinene is then removed by vacuum (Note 7). Tetrahydrofuran, 200 mL, is added, followed by 150 mL of 3 M aqueous NaOH. Hydrogen peroxide (150 mL, 30%) is added dropwise (CAUTION Note 8). Oxidation is complete in 3 hr at 40°C. The reaction mixture is transferred to a separatory funnel and extracted with three 50-mL portions of ethyl ether. The ether layers are combined and dried with copious amounts of anhydrous magnesium sulfate, filtered, and concentrated by rotary evaporation to give an oil. Distillation at 60-65°C (3.0 mm) yields 31 g (0.245 mol) of l-octyn-3-ol, 86% yield (Note 9). The distillation pot residue is a thick oil consisting for the most part of cis-l,5-cyclo-octanediol. An NMR lanthanide shift study showed the alcohol to be 93% (R) and 7% (S), 86% ee, (Note 10 and 11). 

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