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Chapter 9-7 - Synthesis of Alkynes from Acetylides
Organic Chemistry 307: Chapter 9 - Alkynes; Section 7 - Synthesis of Alkynes from Acetylides
Organic Chemistry
Undergraduate 3

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One approach that leads to the synthesis of an alkyne features an electrophile undergoing a nucleophilic attack by an __________ ion.
The electrophile may be an unhindered __________ __________ __________ (undergoes SN2) or it may be a __________ compound (undergoes addition to give an alcohol).
A second approach used to synthesize alkynes features a triple bond being formed by a double __________ of a __________.
This reaction does not enlarge the __________ __________ and isomerization may occur so __________ is useful only when the desired product has the triple bond in a thermodynamically favored position.
1) Dehydrohalogenation
2) Dihalide
3) Carbon skeleton
4) Dehydrohalogenations
An acetylide ion is a strong __________ and a powerful __________.
It can displace a __________ ion from a suitable substrate, giving a substituted acetylene.
For this reaction to produce a good yield, the __________ __________ must be an excellent SN2 substrate: it must be __________ and have no bulky __________ or branches close to the reaction center.
If the back-side approach is hindered, the acetylide ion may abstract a proton, giving elimination by the __________ mechanism.
1) Base
2) Nucleophile
3) Halide
4) Alkyl halide
5) Primary
6) Substituents
7) E2
In addition to displacing __________ ions in SN2 reactions, acetylide ions can add to __________ groups.
1) Halide
2) Carbonyl
Since oxygen is more electronegative than carbon, the C=O double bond is __________ with the oxygen having a partial __________ charge balanced by an equal amount of __________ charge on the carbon atom.
This positively charged carbon atom is __________; attack by a nucleophile places a __________ charge on the electronegative oxygen atom.
The product of such a nucelophilic attack is an __________ ion, a strong base (the conjugate base of an alcohol, a __________ acid).
1) Polarized
2) Negative
3) Positive
4) Electrophilic
5) Negative
6) Alkoxide
7) Weak
An __________ ion can serve as a nucleophile in the addition to a __________ group.
The acetylide ion adds to the carbonyl group to form an __________ ion.
Addition of dilute acid __________ the alkoxide to give an __________.
1) Acetylide
2) Carbonyl
3) Alkoxide
4) Protonates
5) Alcohol
AN acetylide adds to __________ to give a (primary/secondary/tertiary) alcohol with one more carbon atom than there was in the acetylide.
1) Formaldehyde
2) Primary
An acetylide adds to an __________ to give, after protonation, a (primary/secondary/tertiary) alcohol.
The two groups of the alcohol are the __________ and __________ group that was bonded to the carbonyl group of the aldehyde.
1) Aldehyde
2) Secondary
3) Carbonyl
4) Acetylide
A __________ has two alkyl groups bonded to its carbonyl carbon atom.
Addition of an __________, followed by protonation, gives a (primary/secondary/tertiary) alcohol.
The three alkyl groups bonded to the __________ carbon atom (the carbon bearing the alcohol group) are the __________ and the two __________ groups originally bonded to the carbonyl group in the ketone.
1) Ketone
2) Acetylide
3) Tertiary
4) Carbinol
5) Acetylide
6) Alkyl
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