Give the correct order of substitute group in the following
(a) `H_(3)C - underset(underset(CH_(3))(|))overset(overset(CH_(3))(|))(C )- CH_(2) - overset(overset(CH_(3))(|))(CH) - CH_(3)`
(b) `H_(3)C - underset(underset(CH_(3))(|))overset(overset(CH_(3))(|))(C )- underset(underset(CH_(3))(|))(CH) - overset(overset(CH_(3))(|))(CH) - CH_(3)`
(c ) `CH_(3)CH_(2)CH (CH_(3))CH (CH_(3))(CH_(2))(4) CH (CH_(3))_(2)`
(d) `CH_(3)CH_(2)CH (CH_(3))CH (C_(2)H_(5)) CH_(2)CH_(2)CH_(3)`
(e ) `(CH_(3))_(3)C CH (C_(2)H_(5)) CH_(2)CH_(3)`
(f ) `(CH_(3))_(2) CH (CH_(2))_(4) CH (CH_(3)) CH C(C_(2)H_(5))_(2)`

Explanation

(a) `underset("2, 2,4-Trimethylpentane")(H_(3)overset(1)(C ) - underset(underset(CH_(3))(|))overset(overset(CH_(3))(2|))(C ) - overset(3)(CH_(2)) - overset(overset(CH_(3))(4|))(CH)- overset(5)(CH_(3)))`
2, 4, 4-trimethylpentane name is incorrect because in this second substitute is 4, which is high order
(b) `overset(1)(CH_(3)) - underset(underset(CH_(3))(|))overset(overset(CH_(3))(2|))(C )- underset(underset(CH_(3))(|))overset(3)(CH) - overset(overset(CH_(3))(4|))(CH) - overset(5)(CH_(3))`
(i) From the left side if the 1 number is given then the name is 2, 2, 3, 4-tetramethyl and from the right side is the 1 number is given then the name is 2, 3, 4, 4-tetramethyl. From these both name in (i) the order is low so the IUPAC name is 2, 2, 3, 4-tetramethylpentane.
(c ) `overset(1)(CH_(3)) - overset(2)(CH_(2)) - underset(underset(CH_(3))(|))overset(3)(CH)- underset(underset(CH_(3))(|))overset(4)(CH) - overset(5)(CH_(2)) - overset(6)(CH_(2))- overset(7)(CH_(2)) - overset(8)(CH_(2)) - underset(underset(CH_(3))(|))overset(9)(CH)- overset(10)(CH_(3))`
The substitution order from the left side (i) no. given then 3, 4, 9- and from the right side 1 no. given then 2, 7, 8-
High order : `ul(3), 4, 9` so, this is wrong
Low order: `ul(2), 7, 8` so, this is correct
Thus, the correct IUPAC name is 2, 7, 8-trimethyl-decane
Note: (i) In earlier the lowest addition of substitution was taken.
(ii) Now a days the lowest order of substitution is taken
(d) `overset(1)(CH_(3))- overset(2)(CH_(2)) - underset(underset(CH_(3))(|))overset(3)(CH) - underset(underset(CH_(2)CH_(3))(|))overset(4)(CH)- overset(5)(CH_(2))- overset(6)(CH_(2)) - overset(7)(CH_(3))`
(i) 4-ethyl-3-methyl: order is 4, 3
or (ii) 4- ethyl -5-methyl : order is 4, 5
so, the order low (i) and the 4, 3 order in (i) is low then 4, 5
`:.` correct IUPAC name is 4-ethyl-3-methyl -heptane.
(e ) `H_(3) overset(1)(C )- underset(underset(CH_(3))(|))overset(overset(CH_(3))(2|))(C ) - underset(underset(CH_(2)CH_(3))(|))overset(3)(CH)- overset(4)(CH_(2))- overset(5)(CH_(2)) - overset(6)(CH_(2))- overset(7)(CH_(2)) - underset(underset(CH_(3))(|))overset(8)(CH) - underset(underset(CH_(2)CH_(3))(|))overset(9)(CH_(2)) - overset(10)(CH_(2)) overset(11)(CH_(3))`
Substitutes (i) 2, 2, 3, 8, 9 is low order so, correct or substitutes (ii) 3, 4, 9, 10 is high order so, incorrect.
`:.` IUPAC Name: 3, 9-dimethyl, -2, 2, 8-trimethyl-decane
(f ) `overset(1)(CH_(3))- underset(underset(CH_(3))(|))overset(2)(CH) - overset(3)(CH_(2))- overset(4)(CH_(2)) - overset(5)(CH_(2)) - overset(6)(CH_(2)) - underset(underset(CH_(3))(|))overset(7)(CH)- underset(underset(CH_(2)CH_(3))(|))overset(8)(CH) - overset(9)(CH_(2)) - overset(10)(CH_(3))`
(i) From the left side, if the 1 number is given then order is `ul(2)`, 7, 8 so, it is correct
(ii) From the right side, if the 1 number is given then order is `ul(3)`, 4, 7. so, it is incorrect. First substitute order `2 lt` order 3
`:.` IUPAC Name: 8 -ethyl, 2, 7-dimethyldecane