In situ multinuclear solid-state NMR spectroscopy study of Beckmann rearrangement of cyclododecanone oxime in ionic liquids: The nature of catalytic sites — Teresa Blasco (2010) | RDL Network
In situ multinuclear solid-state NMR spectroscopy study of Beckmann rearrangement of cyclododecanone oxime in ionic liquids: The nature of catalytic sites
The Beckmann rearrangement of cyclododecanone oxime into ω-laurolactam has been investigated in four ionic liquids: 1-butyl-3-methylimidazolium hexafluorophosphate and tetrafluoroborate
(
[
C
4
mim
]
+
PF
6
-
,
[
C
4
mim
]
+
BF
4
-
)
, and 1-butyl-2,3-dimethylimidazolium and 1-butyl-4-methylpyridinium hexafluorophosphates
(
[
C
4
mpyr
]
+
PF
6
-
,
[
C
4
m
2
im
]
+
PF
6
-
)
, in a batch reactor as well as by ‘in situ’ multinuclear solid-state NMR spectroscopy. The Beckmann rearrangement reaction of cyclododecanone oxime takes place in
[
C
4
mim
]
+
PF
6
-
and
[
C
4
mpyr
]
+
PF
6
-
with excellent activity and selectivity, while practically null activity is observed in
[
C
4
m
2
im
]
+
PF
6
-
and
[
C
4
mim
]
+
BF
4
-
. The results obtained indicate that a very low level of hydrolysis of the
PF
6
-
anion in
[
C
4
mim
]
+
PF
6
-
and
[
C
4
mpyr
]
+
PF
6
-
occurs under reaction conditions (130°C), and the HF formed at the level of ppm acts as catalyst in the Beckmann rearrangement with excellent conversion and selectivity.
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