Alkynes

Alkynes have the general formula CnH2n-2. The simplest member of the series has the structure

 

 

and is known by the common name acetylene. Higher alkynes are can be considered as derivatives of acetylene and may be so named, e.g.,

Methylacetylene

 

 

 

  1. Give common names for the following compounds.

    2.  

     

     

     

    (a) Dimethylacetylene

    (b) Ethoxyacetylene

    (c) Vinylacetylene

     

     

     

     

     

    IUPAC Names

    Alkyne nomeclature follows along the same lines as alkene nomenclature. The parent chain must contain the triple bond. The "ane" of the corresponding alkane is changed to "yne". The position of the triple bond is indicated by the lower possible number.

     

    2-Pentyne

     

  2. Give the IUPAC name for diethylacetylene.

    3.  

     

     

     

     

     

     

  3. Write the structure indicted by the name 4-heptyne. Is the name correct?
    4.

     

    No.

    The name should be 3-heptyne.

     

     

     

     

  4. Examine the carbon skeleton shown.

 

 

 

(a) How many carbons are contained in the longest chain?

 

 

 

12 carbons in longest chain

 

 

(b) How many carbons are contained in the longest chain containing the triple bond?

 

 

 

11 carbons in longest chain containing triple bond

 

 

 

 

 

 

(c) Give the complete name of the hydrocarbon represented by the skeleton.

 

 

7-Ethyl-2-methyl-5-pentyl-3-undecyne

 

 

 

 

5. How many carbon atoms are indicated by the name 5-ethyl-4-isopropyl-8-dimethyl-2-nonyne? How many hydrogens should be in an alkyne with that number of carbons?

 

 

 

Carbons:

ethyl 2

isopropyl 3

dimethyl 2

nonyne 9

Total 16 carbons

CnH2n-2 = C16H30 30 hydrogens

 

 

 

 

 

  1. Name the following compound:

    2.  

     

     

    Cyclodecyne

     

     

     

    Names of substituents containing triple bonds:

     

     

     

  2. Give the IUPAC name for propargyl chloride.

 

 

3-Chloro-1-propyne

 



8. How many names can you give the following compound.

 

 

 

Ethynylcyclohexane

Cyclohexylethyne

Cyclohexylacetylene (Common name)

 

 

 

 

 

9. Draw the structure of the simplest possible compound containing two carbon-carbon triple bonds. What is the IUPAC name of this compound?

 

 

 

 

 

 

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Polyfunctional
Compounds