1,3-butadiyne

Thus, 1,4-dibenzoyl- 1,3-butadiyne with diazomethane forms 3(5)-benzoylethy-nylpyrazole (yield 59%) (68LA124). In a similar way, the reaction of 2,7-dimethyl-octadiyne-2,7-diol with diazomethane leads to 4-[3-(l-hydroxy-l-methylethyl)-l//-pyrazol-4-yl]-2-methylbut-3-yn-2-ol in 64% yield (58CB1841) (Scheme 7). 

Would you expect a conjugated diyne such as 1,3-butadiyne to undergo Diels-Alder reaction with a dienophile Explain. 

Hexa luoro-2-butyne, vinylacetylene, and 1,3-butadiyne can be hydroaminated without catalyst [265-267]. However, the reaction of 1,3-butadiyne with Et2NH is accelerated and gives a better yield in the presence of silver or silver diacetylide (29% vs. 19% without catalyst) (Eq. 4.67) [268]. 

See 1,3-Butadiyne, and Buten-3-yne, both below See METAL ACETYLIDES... 

A finely divided mixture with excess nitrate ignited when shaken out onto paper. 1,3-Butadiyne... 

Potentially very explosive, it may be handled and transferred by low temperature distillation. It should be stored at —25°C to prevent decomposition and formation of explosive polymers [1]. The critical pressure for explosion is 0.04 bar, but presence of 15-40% of diluents (acetylene, ammonia, carbon dioxide or nitrogen) will raise the critical pressure to 0.92 bar [2], Further data on attenuation by inert diluents of the explosive decomposition of the diyne are available [3], During investigation of the cause of a violent explosion in a plant for separation of higher acetylenes, the most important finding was to keep the concentration of 1,3-butadiyne below 12% in its mixtures. Methanol is a practical diluent [4], The use of butane (at 70 mol%) or other diluents to prevent explosion of 1,3-butadiyne when heated under pressure has been claimed [5], It polymerises rapidly above 0°C. 

In a semimicro synthesis selenophene is prepared from bis(trimethylsilyl)-1,3-butadiyn and NaHSe generated in situ from Se and NaBH4 in aqueous dimethylformamide.52 Other ring cyclization reactions have been performed... 

Complexation of 1,3-butadiynes In the reactions of complex 1 with various butadiynes, binuclear complexes with intact C4 units between the two metal centers are found. The former diynes are transformed to zig-zag butadiene ligands or g-r (l-3),r (2-4)-trans,-trans-tetradehydrobutadiene moieties between two metallocene cores. The bond type in 19 is unknown for the corresponding zirconocene complexes. 

Figure 10.6. Products obtained from permethyltitanocene and permethylzirconocene with 1,3-butadiynes.

Together with the aforementioned results for tetraynes, these complexes show the possibility of extending the reaction pattern from 1,3-butadiynes to more complicated molecules. 

Oxides of Nitrogen See Nitrogen oxide Dienes, etc. f Acetylene, 0686 f 1,3-Butadiyne, 1385... 

Bis-(2-methoxyethyl) ether, 2549 f 1,3-Butadiene, 1480 f 1,3-Butadiyne, 1385 f 2-Butanol, 1695 f Buten-3-yne, 1423 f Butyl ethyl ether, 2540 f Butyl vinyl ether, 2484 f 2-Chloro-1,3-butadiene, 1451 f Chloroethylene, 0730 f 2-Chloroethyl vinyl ether, 1557... 

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