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ORGANIC CHEMISTRY – Naming of alkanes
Answer the following questions on this sheet
1. Draw the skeletal formulae of all alkanes with the molecular formula C6 H14 and name the substances
according to the IUPAC rules. (Elemente, p. 295, A3)
n-hexane
german: n-Hexan
engl:
2-methylpentane
3-methylpentane
2,2-dimethylbutane
2,3-dimethylbutane
2-Methylpentan
3-Methylpentan
2,2-Dimethylbutan
2,3-Dimethylbutan
2. Draw the skeletal formulae of the following molecules. (Elemente, p. 297, A7)
a) 3,3-dimethylhexane
b) 2-methylhexane
c) 3-ethylhexane
d) 3-ethyl-2-methylpentane
e) 2,3,4-trimethylhexane
Which molecules are isomers?
a), c) and d) are isomers of octane.
3. Some of the following names are not correct. Find out the right names and give an explanation.
(Elemente, p. 297, A8)
a) 1-methylhexane
b) 2-ethylhexane
c) 3-ethylhexane
n-heptane
A methyl group at pos
1 extends the chain
d) 2-methylethane
2-methylheptane
ok
An ethyl group at position 2 extends
the chain
e) 3-propyl-2-methyl-3-ethylhexane
n-propane
A methyl group at the
last C extends the
chain
f) 2,2-methylpropane
3-ethyl-2-methyl-3-propylhexane
2,2-dimethylpropane
The side chains must be ordered alphabetically. In fact, the longest chain
is -heptane, but -hexane is preferred
as main name, because with -heptane
a subbranch would occur.
Two methyl groups need
the prefix "di"
4. Name this molecules (Elemente, p. 297, A9)
a)
3,3,5-trimethylheptane
b)
3-ethyl-4-methylheptane
c)
3,3,5,5-tetramethyloctane
d)
3,5-diethyl-2-methyloctane
5. Which of the following formulae represent structural isomers and which ones are identical?
(Elemente, p. 297, A10)
structural isomers:
identical:
a, b, c, e, h: C5H12;
d, f, g, i, j, k, l: C6H14
a, b, h: 2-methylbutane;
Kantonsschule Kreuzlingen, Klaus Hensler
d, l: 2-methylpentane;
g, j: 2,2-dimethylbutane
Che10_AlkanesNames_ARBBLATTengl.doc – 18.02.2010
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