Lesson 4: Alkynes Flashcards
A hydrocarbon with double bonds
Alkenes
Unsaturated hydrocarbon where some hydrogen have been replaced by triple carbon-carbon bonds. (replaced by pi bonds)
Alkynes
General formula of alkynes
CsubnHsub2n-2
In the general formula of alkynes n represents
Number of carbon atoms
Carbons in triple bond are ______________ and have linear geometry
sp hybridized
1 sigma bond and 2 pi bonds=
3 bonds
Carbon triple bond is _________ than carbon double bond
Stronger
Unsaturated Hydrocarbons are easy to break. Opening opportunity for __________.
Reactions
Open bonds from the uncoiling of triple and double bonds, the opened bonds could provide connections for carbon atoms to attach to, a process we call ______________.
Polymerization
In the rules for naming alkynes, you need to find the longest carbon chain that includes both _________ of the ___________.
Carbons, triple bonds
Rules for naming alkynes: Number the longest chain starting at the end _________ to the triple bond.
Closest
Rules for naming an alkyne:
Label each of the ___________ at its corresponding carbon.
Substituents
If there are more than one of the same substituent use the prefixes ____, ____, and ______ and so on.
di, tri and tetra
Rules for naming an alkyne:
If there is an alcohol present, number the longest chain starting at the end closest to it. However, the suffix would be ________, because the alcohol takes priority over the triple bond.
—ynol
Rules for naming an alkyne:
When there are two triple bonds in the molecule, find the longest carbon chain including both the __________. The suffix that would be used to name this molecule would be —diyne.
Triple bonds
Rules for naming an alkyne:
Substituents containing a triple bond are called _________.
Alkynyl
Rules for naming an alkyne:
A molecule that contains both double and triple bond is called an __________. The chain can be numbered starting with the end closest to the functional group that appears first.
Alkenyne
Alkyne nomenclature: Common name
The basis of all common Name for alkyne is the simplest form of alkyne—__________.
Acetylene
Consists of a closed ring of carbon atoms containing one or more triple bonds.
Cycloalkyne
The linear nature of alkyne unit makes cycloalkyne _________. Hence, they are very occurring organic compounds.
Strained
General formula of cycloalkyne
CsubnHsub2n-4
Physical properties of alkyne:
Alkynes are ________, __________ with characteristics that are comparable to those of Alkanes and alkenes.
Unsaturated, nonpolar hydrocarbons
Physical properties of alkynes:
Molecules with a _________ between carbon atoms.
Triple bond
Physical properties of alkynes:
Two types of alkynes
Terminal and internal
Physical properties of alkyne:
A carbon-carbon triple bond at the end of the carbon chain.
Terminal alkynes
Are those that have a carbon-carbon bond in the middle of the carbon chain.
Internal alkynes
Boiling and melting point:
Alkynes have a ___________ because they contain a triple bond.
Higher boiling point
Boiling point and melting point:
____________ is more susceptible to distortion due to the increased number of weakly held electrons in the compound.
Electric field
Boiling and melting points:
Alkynes have higher boiling points because of their ______________.
Linear structure
Boiling and melting points:
Alkynes rise in proportion to the size of their ____________.
Molecular structures
Boiling point:
Alkynes, like ethyne, has linear structure because the carbon atom underwent _____________.
sp hybridization
Boiling point:
Boiling rises with the increase in molar mass for a group of ______________.
Subsequent alkynes
Density:
Alkynes are lighter and has ________ density than water
Lower
Density:
Alkynes become more dense as _______ increases.
Mass
Physical state:
Alkynes are _______ and ________.
Odorless and colorless
Physical state:
The first three alkynes are ______,and the next eight alkynes are _________.
Gases, liquids
Physical state:
All alkynes higher than 11 alkynes are ________.
Solids
Physical state:
The first three alkynes that are all gaseous substances.
Ethyne, propyne and butyne
Solubility:
Alkynes ________ in organic solvents.
Dissolve
Solubility:
Alkynes have slight solubility in ______________.
Polar solvents
Solubility:
Alkynes are ________ in water.
Insoluble
Polarity:
Alkynes are _________ due to slight solubility in polar solvents and insoluble in water.
Nonpolar
Polarity:
Alkynes are more __________ than alkenes and alkanes.
Electronegative
Alkynes are more electronegative than alkenes and alkanes due to their _________ carbon atom.
sp hybridized
Reaction of alkynes:
The principal reaction of the alkynes is _______ across the triple bond to form alkanes.
Addition reaction
Alkynes undergo catalytic hydrogenation with the same catalysts used in _____________.
Alkene hydrogenation
Alkyne hydrogenation follows the same process as _______________.
Alkene hydrogenation
In low temperature liquid ammonia, alkynes can also be __________ with sodium.
Hydrogenated
The process for adding halogens to an alkyne is the same as for adding halogens to alkenes.
Halogenation
Hydrogen halides react with alkynes in the same manner as they do with alkenes.
Hydrohalogenation
The addition of the elements of water across the triple bond of an alkyne leads to the formation of Aldehydes and Ketones.
Hydration
Water adds across the triple bond of an alkyne via a ______________.
Carbocation mechanism
Alkynes are oxidized by the same reagents that oxidize alkenes.
Oxidation
Ozonolysis of an alkyne also leads to ______________.
Carboxylic acid formation
Alkynes can be polymerize by both _________ and _________ methods.
Cationic and free-radical
Alkynes can be polymerized by both cationic and free-radical methods.
Polymerization
Alkynes undergo many of the same reactions as alkenes, but can react twice because of the presence of the two _______ in the triple bonds.
Pi bonds
Three isomers of pentyne:
Pent-1-yne, pent-2-yne and 3-methylbut-1-yne
Triple-bonded carbons are sp-hybridized, and have linear shapes, with the bonded atoms at angles of ______ to each other. Because of this linear shape, geometric isomerism does not occur in alkynes.
180°
The simplest of the alkynes, consisting of two carbon atoms connected by a triple bond, leaving each carbon able to bond to one hydrogen atom.
Ethyne (acetylene)
It is due to the different arrangement of carbon atoms in the chain that is straight-chain or branched.
Chain isomerism
It is due to the difference in the location of the triple bond.
Position isomerism
Alkynes are isometric with alkadienes both being represented by the general formula CsubnHsub2n-2.
Functional isomerism
