ORGANIC CHEMISTRY
Dr Nam T. S. Phan Faculty of Chemical Engineering HCMC University of Technology Office: room 211, B2 Building Phone: 8647256 ext. 5681 Email: ptsnam@hcmut.edu.vn
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Chapter 7: ALKYNES
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An sp hybridized carbon
NOMENCLATURE OF ALKYNES
The IUPAC name of an alkyne is obtained by replacing the “ane” ending of the corresponding alkane with “yne”
In common nomenclature, alkynes are named as ‘substituted acetylenes’
Both ethyne & acetylene are acceptable names for C
H 3
2
2
Lowest possible number, regardless of which functional group gets the lower number
The same low number for both directions, lower number 4 for C=C
PREPARATION OF ALKYNES
Sources of acetylene
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Alkynes by elimination reactions
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REACTIONS OF ALKYNES
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Acidic hydrogen
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Only for primary alkyl halides
E
Additions of hydrogen halides (A
)
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E
)
Additions of halogens (A
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Additions of water – hydration reactions
Markovnikov’s rule
Terminal alkynes are less reactive than internal alkynes,
2+
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need Hg as a catalyst
Additions of boran – hydroboration & oxidation
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Regioselectivity
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Markovnikov’s rule
Anti-Markovnikov
Additions of hydrogen – hydrogenation
Product is alkane
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Product is alkene
Ozonolysis of alkynes
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Ozonolysis used to be employed in structure determination, but has been superseded by spectroscopic methods
Polymerizations
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