Furans compounds

Other furan compounds, best derived from furfural, are of interest although commercial volumes are considerably less than those of furfural, furfuryl alcohol, furan, or tetrahydrofurfuryl alcohol. Some of these compounds are stiU in developmental stages. Apphcations include solvents, resin intermediates, synthetic mbber modifiers, therapeutic uses, as well as general chemical intermediates. 

Group of plastics composed of resins in which the furane ring is an integral portion of the polymer chain made from polymerization or polyconden-sation of furfural, furfural alcohol and other compounds containing furane rings also formed by reaction of furane compounds with an equal weight or less of other compounds. 

In this section some systems are briefly described which make use of furan derivatives as starting materials for chemical transformations which eventually lead to polymeric products. However, with the exception of Section (c), these final products bear little resemblance to the original furan compounds used and are, therefore, only marginally relevant to the context of the present review. 

Keywords furan compounds, hefera-Diels-Alder reactions... 

Among the various derivatives of biomass, furanic compounds obtained from furfural are important (200,0001 year-1). A new family of furanic diethers has been obtained by alkylation of 2,5-furandimethanol or furfuryl alcohol under microwave irradiation with PTC solvent-free conditions [83] (Scheme 8.59). 

The quantities employed correspond to the oxidation of one mole of furan compound by two moles of oxidant. Following the same procedure, except that only one mole of tetraacetate is used, a yield of 79% is obtained. 

L-Sorbose reacts with ethyl acetoaeetate in the same way, affording a high yield of fUran compound which has not yet been obtained crystalline. 

Newth, F. H., The Formation of Furan Compounds from Hexoses, VI, 83-106... 

Grandmaissen, J.L., Chantal, P.D., Kaliaguine, S., Conversion of furanic compounds over HZSM-5, Fuel, 1990, 69, 1058. 

Wilson, C. L. Reaction of Furan Compounds. VII. Thermal Interconver-... 

A consequence of the above observations is that hi ly conjugated furan compounds should display a strong inhibiting role (radical traps) m nree-radical reactions. This has indeed been verified even for structures as simple as ... 

The propensity of the C5 site towards electrophilic substitution has been exploited to prepare functionalized oligomers by cationic polymerization. Thus monomers like isobutene, s ene, the vinyl ethers, etc. polymerize in the presence of simple furan derivatives such as 2-methyl furan to give essentially short chains (DP between 2 and 100 depending on the specific experimental conditions) with a terminal furan ring as a result of predominant transfer onto the C5 position of the added furan compound (20). 

Two distinct working hypotheses have been considered. The first involves the use of furan compounds as additives in a given polymerization system and the second deals with a ecific reaction on the polymer after its synthesis. Both, however, make use of particular chemical specificities of the furan heterocycle. 

Hepatic Effects. The liver is a common target organ for substituted furan compounds (Boyd 1981). Ten days of oral exposure of female mice to a dose of 591 mg/kg/day of 2,3-benzofuran altered the activity of several hepatic enzymes, decreasing the rate of reactions which activate electrophiles and increasing the rate of reactions which deactivate electrophiles (Cha et al. 1985 Heine et al. 1986). No toxicity was reported in this study (Cha et al. 1985 Heine et al. 1986). Liver damage was seen in rats exposed to... 

The most import uni cyclic ethers arc (he furan compounds Furfural is manufactured by treating pentosan with sulfuric acid and steam stripping mil the furfural a n is formed The sources of pentosan arc such agricultural products uv comet tbs. oat hulls, and hagavtc Furfural is used to produce furan and tetrahydro furan fTHF) These products are used as organic intermediates, extraction solvent, polymer solvents, and in polyurethane applications... 

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