Concept Summary

IUPAC Naming Conventions

Hydrocarbons and Alcohols

The International   Union   of  Pure    and Applied Chemistry   (IUPAC) has designated  standards   for

naming  chemical    compounds.  There   are five    steps   in  the process:

First,  find    the longest carbon  chain   in  the compound    that    contains    the highest-priority

functional  group.  This    is  called  the parent  chain.

Second, number  the chain   in  such    a   way that    the highest-priority    functional  group   receives    the

lowest  possible    number. This    group   will    determine   the suffix  of  the molecule.

Third,  name    the substituents    with    a   prefix. Multiple    substituents    of  a   single  type    receive

another prefix  denoting    how many    are present (di–,   tri–,   tetra–, and so  on).

Fourth, assign  a   number  to  each    of  the substituents    depending   on  the carbon  to  which   it  is

bonded.

Finally,    complete    the name    by  alphabetizing   the substituents    and separating  numbers from

each    other   by  commas  and from    words   by  hyphens.

Alkanes are hydrocarbons    without any double  or  triple  bonds.  They    have    the general formula

CnH(2n  +   2).

Alkanes are named   according   to  the number  of  carbons present followed    by  the suffix  –ane.

The first   four    alkanes are methane (CH 4 ),    ethane  (C 2 H 6 ), propane (C 3 H 8 ), and butane  (C 4 H 10 ).

Larger  alkanes use the Greek   root    for the number  (pentane,   hexane, heptane,    octane, and so

on).

Alkenes and alkynes contain double  and triple  bonds,  respectively.

Alkenes are named   by  substituting    –ene    for the suffix  and numbering   the double  bond    by  its

lower-numbered  carbon. Alkynes substitute  –yne    with    the same    numbering.