CHEMISTRY
163 HW 13A
2, 4, 6, 12, 13, 26, 28, 34, 36, 40, 42, 50, 54
13-02
Structure a has the chemical formula CH3CH2CH2CH(CH3)2 or C6H14.
Structure b has the chemical formula CH3CH2CH(CH3)CH2CH3 or C6H14.
Structure c has the chemical formula (CH3)2 CHCH(CH3)2 or C6H14.
Structure d has the chemical formula (CH 3)2 CHCH2CH2CH3 or C6H14.
13-04
Both capillin and pargyline have the C
acrylonitrile does not.
C functional group (capillin has two of these groups!), but
13-06
To find the aromatic rings, we focus on the hexagonal rings in each molecule. Carvone’s sixmembered ring has only one double bond, not the requisite three double bonds plus three single
bonds. Benzyl acetate and cinnamaldehyde do have six-membered rings with sp2-hybridized carbon
atoms and, therefore, they both contain an aromatic ring.
13-12
13-13
Mevacor has 8 chiral carbon atoms.
13-26
The molecular formula of n-hexane is C6H14 and that of cyclohexane is C6H12. Because their
molecular formulas differ, these are not structural isomers.
13-28
For n = 3 (C3H6) the bond angles between the carbons atoms are strained to 60˚ and this cycloalkane
is planar. Likewise, for n = 4 (C4H8) the bond angles between the carbon atoms are strained to 90˚
and this cycloalkane may also be planar but in reality, C4H8 is puckered. For n  5, the bond angle
constraints are released and the cycloalkanes are all puckered.
13-34
13-36
(a) This compound has a molecular formula of C7H16 and has a branched structure; it is an isomer of nheptane.
(b) This compound has a molecular formula of C7H14; it is not an isomer of n-heptane.
(c) This compound has a molecular formula of C 7H16 but has the same linear structure as n-heptane;
it is not an isomer of n-heptane.
(d) This compound has a molecular formula of C8H18; it is not an isomer of n-heptane.
(e) This compound has a molecular formula of C8H18; it is not an isomer of n-heptane.
(f) This compound has a molecular formula of C7H16 and has a branched structure; it is an isomer of nheptane.
The structural isomers of n-octane are (a) 2,3-dimethylpentane and (f) 2,2-dimethylpentane.
13-40
∆Hhydrogenation = [(1  839 kJ/mol) + (2  436 kJ/mol)] + [(1  –348 kJ/mol) + (4  – 413 kJ/mol)] = –
289 kJ
13-42
In order of decreasing van der Waals forces,
13-50
The  electrons in the six-membered ring are delocalized through resonance.
O
O
13-54
Arachidonic acid has four double bonds along its chain. The possible isomers are as follows:
Cis–cis–cis–cis
Trans–trans–cis–cis
Cis–cis–cis–trans
Trans–cis–trans–cis
Cis–cis–trans–cis
Trans–cis–cis–trans
Cis–trans–cis–cis
Trans–trans–trans–cis
Trans–cis–cis–cis
Trans–trans–cis–trans
Cis–cis–trans–trans
Trans–cis–trans–trans
Cis–trans–cis–trans
Cis–trans–trans–trans
Cis–trans–trans–cis
Trans–trans–trans–trans
There are 16 or 42 possible isomers in all for arachidonic acid.
The isomer with all trans double bonds is
HO2C