172
7 C–C Bond Formation via Carbocations in the Methane …
Scheme 7.1 Cleavage of the C–C and C–H bonds of iso-butane in DF–SbF 5 solution via pentacoordinated carbonium ion intermediates (Reprinted with permission from ref. [18]. Copyright 2020
American Chemical Society)
hydride transfer (reaction (7.17)) but also protonation–elimination in direct alkylation
(reaction (7.18)).
+
C
R’
R’
R’
H
C
R
R
H
R
+ H +
(9)
(6)
C
R’
R’
R’
(8)
+
+
+
(7)
C
R
R
R
C
R’
R’
R’
(Intermolecular Hydride Transfer)
(Proton Elimination and Direct Alkylation)
H
C
R
R
R
C
R’
R’
R’
C
R
R
R +
(7.17)
(7.18)
In reactions (7.17) and (7.18), R and R’ are H atoms, and R 3 CH and
+ CR’ 3 are CH 4
and
+ CH 3 , respectively. Thus, reaction (7.18) represents the reaction of CH 4 with
+ CH 3 to produce C 2 H 6 , and also indicates that the alkylation of alkanes (both isoalkane and n-alkane) can directly proceed using superacid catalysts. This process is
explained further in Sect. 7.4.1.
7 C–C Bond Formation via Carbocations in the Methane …
Scheme 7.1 Cleavage of the C–C and C–H bonds of iso-butane in DF–SbF 5 solution via pentacoordinated carbonium ion intermediates (Reprinted with permission from ref. [18]. Copyright 2020
American Chemical Society)
hydride transfer (reaction (7.17)) but also protonation–elimination in direct alkylation
(reaction (7.18)).
+
C
R’
R’
R’
H
C
R
R
H
R
+ H +
(9)
(6)
C
R’
R’
R’
(8)
+
+
+
(7)
C
R
R
R
C
R’
R’
R’
(Intermolecular Hydride Transfer)
(Proton Elimination and Direct Alkylation)
H
C
R
R
R
C
R’
R’
R’
C
R
R
R +
(7.17)
(7.18)
In reactions (7.17) and (7.18), R and R’ are H atoms, and R 3 CH and
+ CR’ 3 are CH 4
and
+ CH 3 , respectively. Thus, reaction (7.18) represents the reaction of CH 4 with
+ CH 3 to produce C 2 H 6 , and also indicates that the alkylation of alkanes (both isoalkane and n-alkane) can directly proceed using superacid catalysts. This process is
explained further in Sect. 7.4.1.