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22 Cards in this Set
- Front
- Back
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define an alkyne
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a hydrocarbon with a triple bond.
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what is the simplest alkyne?
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Acetylene H-C///C-H
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A C-C trible bond results from the interaction of ____ ?
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two sp hybrid oritals of carbon lying 180 degrees from each other along an axis of two unhybridized 2py and 2pz orbitals
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how is the length of a triple bond related to its strength?
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the triple bond is the shortest and therefore strongest known Carbon-Carbon bond
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Explain why the triple bond is linear
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two sp-hybridized carbons approach each other, and this forms one sp-sp sigma bond and two p-p pi bonds. that leaves only two remaining sp orbitals to form bonds to other atoms at a 180 degree angle.
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Naming
begin numbering at... |
the end nearer the triple bond so that the triple bond receives as low a number as possible
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compounds with more than one triple bond are called...
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diynes, triyes, and so forth
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compounds with double and triple bonds are called ___
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enynes
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numbering of an eyne chain starts from the end....
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nearer the first multiple bond, whether double or triple. but double bonds receive lower numbers than triple bonds
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just as there are alkyl groups derived from alkanes, and alkenyl substituents from alkenes, there are ____ groups from alkynes
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alkynyl
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alkynes can be prepared y _________ from alkyl halides in much the same manner as alkenes
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elimination of HX
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what does "vicinal" mean?
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it's a term used to refer to a 1,2 di- substitution pattern.
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give an example of a vicinal molecule
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1,2 dibromoethane is a vicinal dibromide.
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Treatment of ______ with excess _____ results in _______ and formation of an alkyne.
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Treatment of a 1,2-dihaloalkane with excess strong base such as KOH or NaNH2 results in a twofold elimination of HX and fomration of an alkyne.
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how can you obtain the necessary vicinal dehalides for the formation of an alkyne? what is the significance of this?
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they are readily available by addition of Br2 or Cl2 to alkenes. This means that the overall halogenation/dehydrohalogenation sequence gies a way to go from an alkene to an alkyne
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what is a vinylic subsituent?
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one that is attached to a double-bond carbon.
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what does the twofold dehydrohalogenation take place through?
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a vinylic halide intermediate.
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which gets priority in naming: a double or a triple bond?
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double
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Alkynes react with HBR and HCl to yield....
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*vinylic* halides
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Alkynes react with Br2 and Cl2 to yield...
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1,2 dihalides (vicinal dihalides)
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Alkynes can be hydrated by reation with ____ in the presence of ____
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aqueous sulfuric acid in the presence of mercury (11) catalyst.
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Alkyne hydration reaction with aqueous sulfuric acid in the presence of mercury(11) catalyst leads to an intermediate _____ that immediately isomerizes to yield a ketone _______
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intermediate enol
ketone tautomer ...a methyl ketone is producedfrom a terminal alkyne |
