Abstract
M.Sc.
Lewis acids play an important role in catalysis; they are associated with mild conditions,
high selectivities and unique reactivities. Traditional Lewis acids such as AlCb and BF3
successfully catalyse such well known reactions as the Friedel-Crafts acylation reaction,
Aldol condensation reactions and many more. These catalysts, however, must be used in
a stoichiometric amount and are destroyed during the aqueous workup procedures.
Lately, there has been a lot of interest in the role of metal triflate as Lewis acid catalysts.
They were found to be effective in a wide range of reactions when used in catalytic
amounts. They were also found to be recyclable and reusable without the loss of activity.
Most of this research has been centred around the lanthanide triflates as well as
scandium, bismuth and yttrium triflates. Very little research has been done using
aluminium triflate and this triflate forms the focus ofthis study.
The work contained in this dissertation demonstrates that Al(OTf)3 is an efficient catalyst
for the ring opening of a variety of epoxides by alcohols when present in only ppm
amounts. These reactions provided products in very high yields and selectivities. Simple
acyclic and cyclic epoxides readily underwent ring opening reactions with a range of
alcohols, typically providing the monoglycol ethers as single compounds (from the cyclic
epoxides) or as mixtures of the two possible glycol monoethers (from the acyclic
epoxides). In the case of styrene oxide, essentially a single compound was isolated. In
contrast, the glycidyl ethers required slightly higher catalyst loadings before similar rates
and conversions to product were observed. Additionally, an interesting selectivity was
observed in the orientation of the attack of the alcohol onto the epoxide, which appeared
to be chelation controlled.
Similarly, the Al(OTf)3 also catalysed the aminolysis of a variety of epoxides. These
reactions proceeded smoothly with catalytic amounts of the triflate present, and served to
nicely highlight the role that steric and electronic factors played in these reactions.
A preliminary study was carried out into the efficacy of Al(OTf)3 as a catalyst for
Friedel-Crafts acylation and aromatic nitration reactions. From these studies it is evident
that the Al(OTf)3 is indeed an effective catalyst for these reactions when present in substoichiometric
levels and further studies will be carried out in this area in the future.