#4: Alkynes Flashcards
this aliphatic hydrocarbon contains a triple bond.
alkynes
The general formula of alkynes
CnH2n-2
- observed when one s and one p orbital in the same main shell of an atom mix to form two new equivalent orbitals.
- It forms linear molecules with an angle of 180°.
sp hybridization
an orbital that is spherical with the nucleus at its centre
s-orbital
an orbital that dumbbell-shaped
p-orbital
A triple bond in an alkyne consists of ____ and _____
one sigma bond; two pi bonds
overlap of the two p orbitals
pi bond
overlapping sp orbitals, one from each atom, form a ___
sigma bond
The carbon-carbon triple bond forms from two sets of overlapping ____
p orbitals
Alkynes have linear geometry, and the bond angle is ____
180 degrees
In alkynes of four or more carbon atoms, the triple bond can be located in different positions along the chain, leading to the formation of
_____.
structural isomers
Although alkynes possess restricted rotation due to the triple bond, they do not have _______ like the alkenes because the bonding in a carbon‐carbon triple bond is sp hybridized.
stereoisomers
In sp hybridization, the maximum separation between the hybridized orbitals is 180°, so the molecule is ___
linear
alkynes use the suffix
-yne
first rule in naming alkynes
Find the longest carbon chain that includes both carbons of the triple bond.
second rule in naming alkynes
Number the longest chain starting at the end
closest to the triple bond.
If there is an alcohol present in the molecule, number the longest chain starting at the end ____ to it
closest
If there are two triple bonds, the suffix that would be used to name this molecule would be ____.
–diyne
Substituents containing a triple bond are called
alkynyl
A molecule that contains both double and
triple bonds are called an
alkenyne
The chain can be numbered starting with the end _____ to the functional group that appears first.
closest
what kinds of isomerism do alkynes exhibit?
skeletal, positional, and functional isomerism
what kind of isomerism do alkynes not exhibit?
geometric isomerism
internal alkynes are _____ than terminal alkynes.
more stable
The ozonolysis of internal alkynes produces ____
two carboxylic acids
the triple bond is between two carbons
internal alkyne
the triple bond is flanked by hydrogen and a carbon
terminal alkyne
For external alkynes, the ozonolysis results in a
carboxylic acid and carbon dioxide
general formula of cycloalkynes
CnH2n-4
alkynes arranged in a cyclic structure
cycloalkynes
The boiling point and melting point of alkynes increase as their ____ grows bigger
molecular structure
The loss of a hydrogen atom and a halogen atom from adjacent alkane carbon atoms leads to the______. The loss of additional hydrogen and halogen atoms from the double‐bonded carbon atoms leads to ______.
formation of alkene; alkyne formation (Dehydrohalogenation)
In dehydrohalogenation, halogen atoms located on the same carbon are called
geminal dihalide
In dehydrohalogenation, halogen atoms located adjacent carbons are called
vicinal dihalide
Larger alkynes can be generated by reacting an _____, which is generated from a shorter alkyne.
alkyl halide with an acetylide ion (substitution)
Ethyne is commonly called ___ is the simplest alkyne
acetylene
Today, ethyne is normally prepared by the ____.
pyrolysis of methane
The addition of hydrogen to alkynes may lead to the production of alkanes this is _____.
hydrogenation reaction
Addition of hydrogen halides to alkenes become well known and this is formulated by ___ a Russian Chemist in 1869, better known as ____.
Vladimir Marconikov; Markovnicov’s rule
Alkyne addition of water results in the formation of
enol and later converted to carbonyl compound
