Environmental Engineering Reference
In-Depth Information
In the pharmaceutical industry the conversion of sorbitol to isosorbide has been
carried out. Isosorbide is used as an intermediate for a number of products however
this has been limited to applications on small scale with high product specification
and cost. In recent years new markets and applications for isosorbide derivatives
have been explored. Research, media publicity and public concern as to the health
implications for the use of plasticisers in materials such as PVC have lead to inves-
tigation into safer alternatives. One such development is the formation of esters of
isosorbide [1]. These types of compounds have shown suitable performance as a
plasticiser while enjoying the benefits of reduced human toxicity, Fig. 1. Allied to
this the isosorbide component of the plasticiser is bio-derived.
Fig. 1
Isosorbide ester synthesis from sorbitol by dehydration and esterification
Pentoses, from the hemicellulose component of plant material, has been widely
studied and applied. Mainly they are obtained from agricultural waste streams gener-
ated from rice, corn and sugar production. Pentoses under the action of acid, usually
sulphuric acid, results in dehydration and cyclisation resulting in the formation of
furfural. Furfural itself has commercial application as a solvent but can also be con-
verted by reduction to form furfuryl alcohol which can be used polymerised under
acidic conditions to form polymeric resin materials used to form moulds in the
metal (casting) industry. While the formation of hydroxymethyl furfural (HMF),
formed by the acid catalysed dehydration and cyclisation of hexoses has also been
described, its commercial production (to the best of our knowledge) has never been
achieved despite its very rich chemistry. However recent years has seen a resurgence
in interest in HMF and in particular its conversion towards furan ring containing
di-functional monomers such as 2,5-furandicarboxylic acid (2,5-FDA). Here the
emphasis has been the formation of compounds with similar chemical and struc-
tural properties to petrochemically derived monomers such as terephthalic acid thus
offering the possibility to produce bio-derived monomers resulting in polymers with
similar properties to conventional petrochemical materials.
Other strategies towards bio-derived monomers, such as 1,3-propanediol
(1,3-PDO), have also been investigated. While the chemical synthesis of 1,3-PDO
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