Chemistry Reference
In-Depth Information
30 years. However, this is still a rapidly developing area with much to be
done to improve the eciency and economics of the reactions for com-
mercial purposes. In particular, the results of ligand development and im-
proved mechanistic understanding for non-carbonylative coupling can be
expected to result in improved processes involving carbonylation. Also, the
rapid developments in direct arylation and C-H activation can be expected to
be fruitfully applied to oxidative carbonylation. In all these reactions, car-
bonylation products are formed in competition with by-products arising
from non-carbonylative processes, so an improved understanding of the
mechanism of these reactions will aid in maximizing specificity. In addition,
a greater understanding of the role of additives in stabilizing Pd with
respect to reduction and precipitation will be helpful. Clearly, from the
results discussed above, this includes details such as choice of solvent and
the nature of acids and bases and of oxidants. Regarding the substrates
applied, iodide and bromide compounds and triflates have been extensively
studied, but the cheaper but less activated chlorides, tosylates and mesylates
are less commonly reported, and improved conditions for these are
needed. In the case of alkyl halides, radical reactions are the main pathway
in carbonylation reactions, with more effort still needed to improve the
eciency.
References
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(d) A. Schoenberg and R. F. Heck, J. Am. Chem. Soc., 1974, 96, 7761; For
further details on carbonylation processes, see L. Kollar (ed.), Modern
Carbonylation Methods, Wiley-VCH, Weinheim, 2008.
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