Aldehyde furfur

Chlor-benzaldehyd 4-Methoxy-benzaldehyd 4-Methyl-benz aldehyd Furfural... 

Furfural exhibits high selectivity at elevated temperatures (175° to 250° F.) this characteristic results in the benefits of reduced viscosity and high temperature gradient and permits operation on waxy stocks. At ambient temperatures, kerosenes and gas oils may be extracted. Water in furfural has a bad effect on its extraction efficiency therefore, solvent recovery systems must include dehydration facilities. From its chemical composition aldehyde furfural appears to be unstable. However, when handled in accordance with standard operating procedures, decomposition and polymerization are negligible. 

A comprehensive study of the volatiles from strawberries was conducted by McFadden et al. (236). Over 150 components were detected, and the major volatiles were identified from strawberries. The major components included alcohols, esters, acetals, aldehydes, furfural, methyl furfural, aromatic aldehydes, and ketones. 

The fermentation inhibitors include furan aldehydes, aliphatic acids, and phenolic compounds. The furan aldehydes, furfural, and hydroxymethyl furfural (HMF), are formed from pentoses and hexoses, respectively (4,5). Several studies indicate that furfural inhibits Saccharomyces cerevisiae, at least when present in high concentrations (6-10). HMF has a similar effect (11,12). 

Hydrolysis of lignocellulose is necessary to enable its use for ethanol production. However, when lignocellulosic materials are hydrolyzed with acid, compounds toxic to the yeast cells are released. The inhibitors are of three main types aldehydes, organic acids, and phenolic compounds. Among the aldehydes, furfural and hydroxymethylfurfural (HMF) are typically found in high concentrations—particularly in dilute-acid hydrolysates (1,2). These compounds have been shown to inhibit certain enzymes in the catabolism necessary for cell growth (3-9). 

Cork products can also emit considerable amounts of the aldehyde furfural (2-furancarboxaldehyde) with surface-specific emission rates SER, > 1,000 pg m - h [57], whereby the release of the furfural generally corresponds with that of acetic acid. The cause for the formation of furfural is the thermal decomposition of the hemicelluloses contained in the cork at temperatures above 150 °C, while acetic acid is formed by the separation of acetyl groups. Further by-products identified in the thermal treatment of natural cork were formic acid and hydroxymethylfurfural [58]. 

Alcohol per cent by volume Extract per cent Total acid Non- volatile acid Ethers Higher alcohols (A.-M.) Aldehydes Furfural... 

Nature of Sample Alcohol per cent by volume Volatile acid Ethers Higher alcohols (Teed) Aldehydes Furfural Total coefficient... 

Original proof Color Solids Acids Esters Aldehydes Furfural Fusel oil... 

Aldehydes are organic compounds that have a carbonyl group (-CHO) on the terminal carbon atom of a hydrocarbon chain or attached to an aromatic or heterocyclic ring. The aliphatic aldehydes are useful as chemical intermediates in synthetic chemistry where oxidation produces the corresponding acid and reduction yields the alcohol structure. Condensation reactions of the aldehydes with phenol, urea, or melamine yields useful resinous products. A useful heterocyclic aldehyde, furfural or 2-furaldehyde (the aldehyde group attached to the 2 position on the furan ring), is both a reactant in synthetic chemistry and has several specialized uses as a solvent. 

The one- and two-carbon aldehydes, formaldehyde and acetaldehyde, are gaseous products at ambient temperatures. Formaldehyde boils at -2PC while acetaldehyde boils at 20 C. Formaldehyde is most often used as a 37-55 wt% aqueous solution or as an alcoholic solution containing some 55 wt% formaldehyde. Methanol and n-butanol are the two alcohols often used for the formaldehyde solutions. Other aliphatic aldehydes useful as chemical intermediates include propionaldehyde (b.p. 48 C) and two butyl aldehydes, rt-butyraldehyde (b.p. 75"C) and isobutyraldehyde (b.p. 64"C). The one commercially important heterocyclic aldehyde, furfural, is a high boiling-point (161.7 0 liquid. 

Condensation is stopped by adjusting pH to 5-8. The prepolymer is stable for several months (>38 °C). Further condensation with additional furfuryl alcohol or with aldehydes (furfural or formaldehyde) and with phenol or urea is again activated by strong acids. 

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