8
1 Parent Structures
instead of ... ane; in this case the free valence is always assigned locant 1
(that often can be ommitted). There is a growing tendency, however, to
eventually use only the un abbreviated ending ... anyl, which could then
also be given locants other than 1, e.g.: 2-Methylpropan-2-yl instead of
1,I-Dimethylethyl (= tert-Butyl).
C22H46 Docosane, C44H90 Tetratetracontane,
-C75Hl5l Pentaheptacontyl, -Cl2lH243 Henicosahectyl,
C9876H 19754 Hexaheptacontaoctactanonaliane
Unsaturated acyclic hydrocarbons with double and/or triple bonds are
generally designated as alkenes, alkynes, and alkenynes; multiple unsaturation is indicated by the numerical prefixes di, tri, etc.: alkatrienes,
alkenediynes etc.
The class names of the corresponding substituent groups are formed by
suffixing the syllable ... yl: alkadienetriynyl etc.
To name individual members the principles outlined for saturated
systems are applied accordingly; trivial names are retained only for Methylene CH2, Ethylene H2C=CH2 , Allene H2C=C=CH2 , and Acetylene
HC=CH.
Chains are numbered in such a way that multiple bonds are assigned the
smallest numbers possible; if there is a choice double bonds are given the
lowest numbers.
5 4
3
2
1
2
H3C-CHrCH=CH-CH3 Pent-2-ene, H3C-C=C-CH3 But-2-yne
2
1
H2C=CH -CHrC=C-CH = CH2 Hepta -1 ,6-dien -3-yne
3
1
H3C-CH=CH-C=CH Pent-3-en-l-yne but:
1 2
4
H3C-CH=CH-C=C-CH3 Hex-2-en-4-yne
1
2
H2C=C=CH -C30H61 Tritriaconta-l,2-diene
In the corresponding substituent groups the position of attachment is
again assigned locant 1, only then are multiple bonds ordered as shown
above:
HC=C- Ethynyl
HC=C-CH=CH-(CH2hoCHr Pentacos-22-ene-24-ynyl.
Trivial designations are retained for the groups Vinyl H2C=CH- (systematic name: Ethenyl) and Allyl H2C=CH-CHr (systematic name: Prop-2enyl).
1 Parent Structures
instead of ... ane; in this case the free valence is always assigned locant 1
(that often can be ommitted). There is a growing tendency, however, to
eventually use only the un abbreviated ending ... anyl, which could then
also be given locants other than 1, e.g.: 2-Methylpropan-2-yl instead of
1,I-Dimethylethyl (= tert-Butyl).
C22H46 Docosane, C44H90 Tetratetracontane,
-C75Hl5l Pentaheptacontyl, -Cl2lH243 Henicosahectyl,
C9876H 19754 Hexaheptacontaoctactanonaliane
Unsaturated acyclic hydrocarbons with double and/or triple bonds are
generally designated as alkenes, alkynes, and alkenynes; multiple unsaturation is indicated by the numerical prefixes di, tri, etc.: alkatrienes,
alkenediynes etc.
The class names of the corresponding substituent groups are formed by
suffixing the syllable ... yl: alkadienetriynyl etc.
To name individual members the principles outlined for saturated
systems are applied accordingly; trivial names are retained only for Methylene CH2, Ethylene H2C=CH2 , Allene H2C=C=CH2 , and Acetylene
HC=CH.
Chains are numbered in such a way that multiple bonds are assigned the
smallest numbers possible; if there is a choice double bonds are given the
lowest numbers.
5 4
3
2
1
2
H3C-CHrCH=CH-CH3 Pent-2-ene, H3C-C=C-CH3 But-2-yne
2
1
H2C=CH -CHrC=C-CH = CH2 Hepta -1 ,6-dien -3-yne
3
1
H3C-CH=CH-C=CH Pent-3-en-l-yne but:
1 2
4
H3C-CH=CH-C=C-CH3 Hex-2-en-4-yne
1
2
H2C=C=CH -C30H61 Tritriaconta-l,2-diene
In the corresponding substituent groups the position of attachment is
again assigned locant 1, only then are multiple bonds ordered as shown
above:
HC=C- Ethynyl
HC=C-CH=CH-(CH2hoCHr Pentacos-22-ene-24-ynyl.
Trivial designations are retained for the groups Vinyl H2C=CH- (systematic name: Ethenyl) and Allyl H2C=CH-CHr (systematic name: Prop-2enyl).