11.15 (i) Draw the structures of all isomeric alcohols of molecular formula C5H12O and give their IUPAC names. (ii) Classify the isomers of alcohols in question 11.3 (i) as primary, secondary and tertiary alcohols.

11.15 The structures of all isomeric alcohols of C5H12O are given below: Naming is done by the conventional method. The -OH group is attached on the first carbon. (b) 3-Methylbutan-1-ol Butane is the longest chain and methyl is the substituent group. (c) 3-Methylbutan-1-ol the longest chain is butane and conventional naming method is used. (d) 2,2-Dimethylpropan-1-ol Isomer is made by transforming the principal carbon into tertiary type. The longest chain is butane and named accordingly. (e) Pentan-2-ol the longest chain is pentane and the numbering is chosen from the minimum position. Butane is the longest chain, further numbering is done by choosing a minimum position for the -OH group followed by other substituents. (g) Pentan-3-ol Conventional method of naming is used. (h) 2-Methylbutan-2-ol Butane is the longest chain and substituents are named accordingly by looking into minimum position. (f) 3-Methylbutan-2-ol Butane is the longest chain, further numbering is done by choosing a minimum position for the -OH group followed by other substituents. (g) Pentan-3-ol Conventional method of naming is used. (h) 2-Methylbutan-2-ol Butane is the longest chain and substituents are named accordingly by looking into minimum position. (A) Primary alcohol Explanation (i) Pentan-1-ol (ii) 2-Methylbutan-1-ol (iii) 3-Methylbutan-1-ol (iv) 2,2-Dimethylpropan-1-ol The -OH group is attached to the carbon that is attached to another single carbon. (B) Secondary alcohol (i) Pentan-2-ol (ii) 3-Methylbutan-2-ol (iii) Pentan-3-ol The -OH group is attached to the carbon that is attached to another two carbons. (C) Secondary alcohol (i) 2-Methylbutan-2-ol The -OH group is attached to the carbon group that is further attached to another three carbon atoms.