Formation of alkynes through double elimination of vicinal dibromides
Description: Sodium amide will convert 1,2-dihalides (“vicinal dihalides”) into alkynes through two consecutive elimination reactions.
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Real-Life Examples:
Org. Synth. 1926, 6, 26
DOI Link:10.15227/orgsyn.006.0026
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Org. Synth. 1922, 2, 67
DOI Link:10.15227/orgsyn.002.0067
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Org. Synth. 1938, 18, 3
DOI Link: 10.15227/orgsyn.018.0003
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Org. Synth. 1932, 12, 60
DOI Link: 10.15227/orgsyn.012.0060
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Org. Synth. 1942, 22, 50
DOI Link: 10.15227/orgsyn.022.0050
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Org. Synth. 1958, 38, 70
DOI Link: 10.15227/orgsyn.038.0070
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Org. Synth. 1950, 30, 72
DOI Link: 10.15227/orgsyn.030.0072
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Org. Synth. 1957, 37, 77
DOI Link: 10.15227/orgsyn.037.0077
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Org. Synth. 1952, 32, 104
DOI Link: 10.15227/orgsyn.032.0104
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Org. Synth. 1979, 59, 10
DOI Link: 10.15227/orgsyn.059.0010
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Does this work the same way for Geminal Dihalides?
Yes it does!
Would this also work with geminal dihalides?
Yes, it should.
My course taught us that we need three molar equivalents of NaNH2 for this reaction, as it prevents the formation of the alkynyl salt.
True, for terminal alkynes. Once the alkyne is formed, it can then be deprotonated by NaNH2 in solution. For practical purposes, three equivalents for the formation of terminal alkynes is best.