How the polarity of carbohydrates can be used in chemistry - Carbohydrate Chemistry: Chemical and Biological Approaches - page 42

This is the same philosophy which supports the design of new bio-
based compounds targeting a desired property. In the following, we will
focus on amphiphilicity as the targeted property, as it is strongly related
with the issue of carbohydrate polarity. Indeed, the ton-scale availability
of sugars has made their use very attractive when designing new types of
amphiphilic derivatives in which they import their highly polar char-
acter. 49-51 Possible applications cover many fields, in particular the fields
of biobased surfactants (such as the archetypical alkylpolyglucosides
family, 52 but also the interesting N-acylglycosylamines which were stud-
ied by Lubineau and Aug ´ and are discussed in a separate chapter in this
topic by Aug ´ and colleagues) and biobased monomers. 53-58 This will be
further exemplified with recent contributions of our group, notably using
sucrose or isomaltulose.
For amphiphilic targets, the strategy is to attach one specific function
or molecular moiety on the sugar backbone. To do so, there are not many
manners, sugars being essentially polyols with either acetal or hemiacetal
functions. When a hemiacetal group is present, the masked carbonyl
function can be selectively transformed, for example by glycosidation or
reductive amination. But when there is no hemiacetal group (like in su-
crose), the substrate becomes a simple polyol. At this stage, the main
parameter becomes the ability to selectively substitute one given hydroxyl
group among others, eight in the case of sucrose. 59 Indeed, selectivity is
essential because it is related to the specific properties of the targeted
molecules. In terms of degree of substitution, as shown in Fig. 1, the
substitution pattern will influence the emulsification properties of su-
crose esters, a monostearate being an oil-in-water emulsifier, whereas its
disubstituted analogue is a water-in-oil emulsifier.
Though with lower impact on the main physicochemical properties,
the regiochemistry can also influence the behaviour of the products
(Fig. 2). In keeping with the interesting example of sucrose esters, which
are historical biobased surfactants developed in the middle of the 20 th
century and used as food or cosmetic emulsifiers, 49,60 it was found that

Fig. 1 Influence of the degree of substitution on solution or thermotropic properties.