The DFT-based reactivity descriptors “local softness” and
“local hardness” are used as reactivity indices to
predict the reactivity sequences (both intramolecular and
intermolecular) of carbonyl compounds toward
nucleophilic attack on them. The finite difference approximation
is used to calculate local softness, whereas
local hardness is approximated by
−V
el/2N, where
V
el is the electronic part of the molecular
electrostatic
potential. Both aldehydes and ketones, aliphatic and aromatic,
have been selected as systems. Critical cases,
e.g., C6H5CHCHCHO,
CH3CHCHCHO, and CH2CHCHO, where a
CC double bond is in conjugation
with the CO group, are also considered. Two new reactivity
descriptors are proposed, “relative
electrophilicity”
(s
k
+/s
k
-)
and “relative nucleophilicity”
(s
k
-/s
k
+),
which will help to locate the preferable
reactive sites. Our results show that local hardness can be used
as a guiding parameter when constructing
intermolecular reactivity sequences.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.