Pyrolysis of sugars

These fragments have good resemblance with compounds detected in pyrolysis of sugars (see Sections 7.1 and 7.2) such as ... 

Ever since the work of Cemiani in 1951, the pyrolysis of sugars has been studied at temperatures ranging from 200 to 1000°. Above 200°, or 250°, deep changes occur in sugars, and a great variety of products is formed, such as carbon mon-, and di-oxide, hydrocarbons (among them alkanes, alkenes, and aromatic hydrocarbons), alcohols, aldehydes, ketones, and several furan derivatives. The number, and character, of the products depend, at least, on both the temperature and the time of reaction. Controversy exists in respect to the influence of the atmosphere in which the pyrolysis takes place. 

Acetone was originally observed about 1595 as a product of the distillation of sugar of lead (lead acetate). In the nineteenth century it was obtained by the destmctive distillation of metal acetates, wood, and carbohydrates with lime, and pyrolysis of citric acid. Its composition was determined by Liebig and Dumas in 1832. 

A recent study extensively investigated the pyrolysis of polysaccharide binders, with and without a silylating agent [56]. Some of the main results relative to the pyrolysis silylation of sugars and polysaccharide binders can be summarised as follows [56 59] ... 

SCHEME 32. Anhydro sugars obtained by pyrolysis of cellulose. 

D. Fabbri, C. Torri, and V. Baravelli, Effect of zeolites and nanopowder metal oxides on the distribution of chiral anhydro sugars evolved from pyrolysis of cellulose An analytical study, J. Anal. Appl. Pyrolysis, 80 (2007) 24-29. 

The extraction of environmental or geological particulate matter with solvents, solvent mixtures or supercritical carbon dioxide is the preferred method, because it results in minimum alteration of its polar components, avoids hydrolysis of anhydrides, esters, etc. and is highly efficient for most organic compounds (even sugars). Other workers have reported the direct vaporization by thermal desorption or flash pyrolysis of organic compounds from particulate matter into GC, MS, or GC-MS instruments. Those methods work fine for neutral compounds (e.g. hydrocarbons) but should be used with caution when analyzing polar or labile compounds. 

Thus, by the Maillard reaction in different browning systems of sugars and amino compounds, some mutagenic substances were formed, although their activities are quite weak compared with those formed by pyrolysis of amino acids. They were confirmed as intermediates and some of them were identified as furan, pyrrole, or thiazolidine derivatives formed from glucose and amino acids... 

J-Hydroxyamino acids under pyrolysis conditions (250 °C) can give rise to a-hydroxyaldehydes and a-aminoalcohols, which can enrich the pool of sugar fragmentation products.59... 

The volatiles produced by sugar degradation can make an important contribution to flavour. Pyrolysis of glucose at 300 °C allowed 56 compounds to be identified, the main product being l,4 3,6-dianhydroglucopyranose.567 More than 100 volatiles were separated when glucose was heated at 250 °C for 30 min in air or in nitrogen 4-hydroxy-2-pentenoic acid lactone, 1-(2-furyl)propane-l,2-dione, and 3-methyl-cyclopentane-1,2-dione were identified as new products.568... 

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