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Chapter 13
Alkynes
31
Organic Chemistry
Undergraduate 2
11/30/2014

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Term
alkyne
Definition
a carbon-carbon triple bond functional group
Term
What is the common name of the smallest alkyne, C2H2
Definition
acetylene
Term
In IUPAC nomenclature for alkynes, the rules for naming alkenes also apply, except the ending _____ replaces the ending "-ene"
Definition
"-yne"
Term
terminal
Definition
alkynes having the general structure: RC(triple bond)CH
Term
internal
Definition
alkynes having the general structure: RC(triple bond)CR'
Term
alkynyl groups
Definition
substituents bearing a triple bond
Term
ethynyl substituent
Definition
-C(triple bond)CH
Term
2-propynyl substituent
Definition
-CH2C(triple bond)CH
Term
alkenyne
Definition
in IUPAC nomenclature, a hydrocarbon containing both double & triple bonds
Term
When a double bond and a triple bond are equidistant from either terminus, the _____ bond is given the lower number
Definition
double
Term
alkynols
Definition
alkynes incorporation the hydroxy function
Term
The _____ group takes precedence over both double & triple bonds in the numbering of a chain
Definition
OH
Term
Strong bases such as sodium amide in liquid ammonia, alkyllithiums, & Grignard reagents can deprotonate terminal alkynes to the corresponding _____
Definition
alkynyl anions
Term
halogenation-double dehydrohalogenation
Definition
a means of converting alkenes into the corresponding alkynes;
1. add halogen
2. add NaNH2, liquid NH3
3. add H2O
Term
alkenyl halides
Definition
haloalkenes
Term
Although mixtures of E- and Z-haloalkenes are in principle possible, with diastereomerically pure vicinal dihaloalkanes only one product is formed because elimination proceeds stereospecifically _____
Definition
anti
Term
Lindlar catalyst
Definition
a modified catalyst that stops alkyne hydrogenation at the intermediate alkene stage
Term
As with the catalytic hydrogenation of alkenes, the addition of H2 is a _____ process
Definition
syn
Term
When we use _____ dissolved in liquid ammonia as the reagent for the reduction of alkynes, we obtain trans alkenes as the products
Definition
sodium metal
Term
dissolving-metal reduction
Definition
using sodium metal dissolved in liquid ammonia to reduce an alkyne to obtain the trans alkene
Term
Dissolving-metal reduction is a _____ process
Definition
trans
Term
The stereochemistry of addition of a hydrogen halide to an internal alkene is typically _____, particularly when excess halide ion is used
Definition
anti
Term
geminal dihaloalkane
Definition
addition of a second molecule of H-X giving the product with both X atoms bound to the same carbon
Term
Electrophilic addition of halogen to alkynes proceeds through the intermediacy of isolable vicinal dihaloalkanes, the products of a single _____ addition
Definition
anti
Term
enols
Definition
the alcohol product when water is added to alkynes in a Markovnikov sense; the hydroxy group is attached to a double-bonded carbon
Term
tautomerism
Definition
the process of enols spontaneously rearranging to the isomeric carbonyl compound; interconverts two isomers by simultaneous proton & double-bond shifts
Term
tautomerize
Definition
the process of going from an enol to a carbonyl compound
Term
tautomers
Definition
the enol & carbonyl species
Term
As with alkenes, hydrogen bromide can add to triple bonds and both _____ & _____ additions are observed
Definition
syn & anti
Term
Heck reaction
Definition
in the presence of soluble complexes of metals such as Ni & Pd, alkenyl halides undergo carbon-carbon bond formation with alkenes to produce dienes; a molecule of hydrogen halide is liberated
Term
4 step mechanism for the Heck reaction
Definition
1. attack of the metal on the alkenyl halide to give the alkenylmetal halide
2. the alkene then complexes with the metal
3. the alkene inserts itself into the carbon-metal bond, forming the new carbon-carbon linkage
4. elimination of HX in an E2-like manner gives the diene product & frees the metal catalyst
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