Diacetylene: Preparation, Purification, and Ultraviolet Spectrum

Abstract

Diacetylene was prepared by the reaction of 1,4-dichloro-2-butyne with sodium hydroxide. Three modifications of procedure were tried to determine which gave the highest yield and purest product. Evidence that the by-product is 2-chloro-2-butene-3-yne is presented. Several methods for purifying the diacetylene were investigated. The ultraviolet spectrum with molar extinction coefficients is given. INTRODUCTIONA sample of very pure diacetylene was required for polymerization and spectroscopic studies. In recent years most investigators have prepared it by the dehydrochlorination of 1,4-dichloro-2-butyne with sodium hydroxide (1, 2, 3, 4, 5) but only one (4) appears t o have reported that the product is not entirely pure. However, no indication of the nature of the impurity was given. RESULTS ISeveral modifications of the dehydrochlorinatio~~ were tried t o determine which gave the highest yield and purest product. T h e yields were highest when 40% aqueous sodium hydroxide solution (285% of theory) was added to a 25Yo solution of 1,4-dichloro-2-butyne2 in ethyl alcohol a t 65-75' over a period of 1 hour (1) and the product was swept o u t of the reaction flaslc with a stream of hydrogen. However, a small percentage of a by-product having a parent peak of 86 in its mass spectrum, as well as tarry high polymers, also formed. When the procedure was reversed and the dichlorobutyne in alcohol was added to the sodium hydroxide, the yield of diacetylene was substantially lower and the fractionated product contained about the same co~icentration of the same impurity. When pure dichlorobutyne was added to 43y0 sodiunl hydroxide solution a t 115', the yield was still lower but the relative amount of the above impurity was lower. Some acetylene and methyl acetylene also formed and were detected by their mass spectra.From the ratio of the 87 t o the 86 mass peak, the spectr~lm indicates that the impurity contains four carbon atoms and the ratio of the 86 to the 88 peak is in goocl agreement with the lcnown ratio of C135 t o C137. I t would thus appear that its empirical formula is CIHsC1. I t also has a strong absorption a t 224 to 245 111p in the ultraviolet and its extinction coefficients are of a higher order thaii those of diacetylene, indicating two conjugated ethylenic groups or an ethylenic together with an acetylenic. From the above evidence, there would appear to be little doubt that this conlpound formed, even in the presence of a large excess of sodium hydl-oxide, by the incomplete dehydrochlorination of the dichlorobutyne and could theoretically have the structure I , 11, or 111.T o establish its identity, its infrared spectrum was obtained and a comparison made of the out-of-plane vibrations of its olefinic hytlrogens with those of four compounds 'Matzuscript

The reaction H + C4H2: Absolute rate constant measurement and implication for atmospheric modeling of Titan

“…During these procedures, the pressure of the vacuum distilling diacetylene was maintained, via control of temperature, at less than 5 Torr in order to minimize polymerization of the diacetylene. Analysis by mass spectrometry showed the diacetylene to be more than 99% pure with C2H 2 (• 0.3 %) and a constituent (• 0.4%) at mass peak 86 (probably CH 2 = CC1-C•CH, Georgieff and Richard [1958]) being the only measurable impurities.…”

Electron delocalization in mixed-valence butadienediyl-bridged diruthenium complexes

“…by using neat diacetylene instead of Me3SiC4SiMe3/NBu4F/THF) [16] . Butadiyne was prepared from I ,4-dichloro-2-butyne (Lancaster) on a 4-mmol scale by a slight modification of a published procedure [18] and isolated at 195 K as a white, crystalline solid.…”

Long-lived higher excited state luminescence from new ruthenium(II)–allenylidene complexes

“…As a representative, the procedure leading to compound 2b is described. cis-RuCI2(dppmh [30] (0.175 g, 0.186 mmol) and NaSbF 6 (0.192 g, 0.744 mmol) were suspended in PhCI (40 ml) and excess butadiyne [31] were added by pipette. The suspension was stirred under ambient conditions for 30 min whereupon a green color developed .…”