Hydrogenation of the Triple Bond¹

Abstract

An attempt to recover the hydrocarbon from the picrate by means of activated alumina and super-cel was unsuccessful. The process finally adopted was to decompose a benzene solution of the picrate a t room temperature with dilute ammonium hydroxide. The benzene extract was washed, dried, and evaporated i n vacuo at room temperature, as rapidly as possible. This afforded a yellow solid, rn. p. 52-54' with preliminary shrinkage and softening.Anal.1o Calcd. for C!&&R: C, 92.26; H, 7.74. Found: C, 91.94; H, 7.84. Subsequent analysesl0 at Alberta gave slightly lower carbon values (C, 91.46, 91.39; H, 7.64, 7.73). The sample having the analysis reported above when analyzed ten days later at Harvard gave values indicating the absorption of oxygen (C, 88.79, 88.93; H, 7.64, 7.83).The deteriorated sample melted unsharply a t 80°, and gas was evolved at a temperature of 120"; the fluorescence in solution was markedly diminished. Attempts to crystallize fresh samples of the hydrocarbon from dilute acetic acid, 95% ethanol, benzene or petroleum ether were unsuccessful. Once the hydrocarbon was obtained as long yellow needles, m. p. 47-50', from an alcoholic sohtion of the picrate treated with ammonium hydroxide.Attempts to purify these crystals further by the use of alumina resulted in the loss of the material. summary 1,2,9,1O-Tetramethylanthracene, of interest as a model of a potent carcinogen, has been synthesized and characterized in the form of the picrate, trinitrobenzene complex, and two methoxy derivatives. The hydrocarbon is very sensitive to air. (10) Semi-microanalyses puformed by one of us (Monoalkylacetylenes, treated with sodium in liquid ammonia, are one-third hydrogenated to the corresponding olefins, and two-thirds metalated. Dialkylacetylenes are reduced to the trans olefins whose physical properties are markedly different from those of the olefin obtained by catalytic hydrogenation. The latter have been labeled as cis compounds and claimed to be pure by Campbell and Eby.*We have found that monoalkylacetylenes can be reduced quantitath ely by the theoretical amount of sodium in liquid ammonia containing an ammonium salt, and that no hydrogen escapes. Under the same circumstances, dialkyl acetylenes are inefficiently reduced, hydrogen is evolved, and more than the theoretical amount of sodium is consumed. Ammonium chloride, which is appreciably soluble in liquid ammonia, gives off some hydrogen and causes an inefficient reduction in every case, while ammonium sulfate, which is nearly insoluble, proved almost l OOyo efficient in the reduction of monoalkylacetylenes. From these results, it is deduced that the hydrogen re-(1) The detailed preparation of acetylenic compounds in better yields and purity than recorded in theliterature has been submitted t o the Editor of Indutfrial and Engineering Chemistry. Practical directions for making sodium amide and sodium acetylide efficiently and handling them safely are described by u s in "Inorganic Synthc\cs,'' Vol. 11 (in press), John Wiley and Sons, Inc.. New York, N....

ChemInform Abstract: On the Thermal Cycloisomerization of Long‐Chain Alkylacetylenes in the Gas Phase.

“…and 5-Methyl-f-hexyne (2) were prepared by reaction of sodium acetylide with n-butyl and isoamyl bromide, resp., in liquid ammonia (-60 'C) as described in ref. 26). Yields, boiling points and refractivities agreed with the data published (1: b.p.…”

Reductions of CC and CC by Noncatalytic Chemical Methods

“…The proposed mechanism for the reduction of dialkylacetylenes by sodium in HMPA in the presence of a proton donor is illustrated in equation (18). Further reduction of (48) by sodium produces the trans-sodiovinyl compound (49), which on protonation produces the trans-alkene (50). Further reduction of (48) by sodium produces the trans-sodiovinyl compound (49), which on protonation produces the trans-alkene (50).…”

“…49 In the absence of ammonium ion, however, extensive metallation of the l-alkyne occurs. 49 In the absence of ammonium ion, however, extensive metallation of the l-alkyne occurs.…”

“…49 In the absence of ammonium ion, however, extensive metallation of the l-alkyne occurs. 49 Benkeser et ale have reported that the reduction of 3-and 5-octyne with lithium in ethylamine at -78°C produces the corresponding trans-alkenes in good yield. 49 Benkeser et ale have reported that the reduction of 3-and 5-octyne with lithium in ethylamine at -78°C produces the corresponding trans-alkenes in good yield.…”

Reactions of Sodium with Organic Compounds

“…Acetylenes, for example, are converted to sodium acetylides by metallic sodium. The reaction in this case is complicated by the fact that the liberated hydrogen reduces one third of the acetylene to an olefin (14) :…”