Treatment of beech sawdust with a series of mono-and dicarboxylic acids in benzene solution at 25-30' in the presence of molar proportions of trifluoroacetic anhydride resulted in esterification of the cell wall components. The esterification is shown to be due in part to acylation by the carboxylic acid and in part to trifluoroacetylation. The latter caused discoloration of the wood due to slow hydrolytic release of trifluoroacetic acid on storage at room temperature. Similar esterification of sapwood lengths of Ponderosa pine resulted in surface modification only and was accompanied by a significant decrease in impact strength property.In the presence of increasing concentrations of trifluoroacetic acid liberated during reaction, the acylating power, rather than trifluoroacetylating power, of the acyl trifluoroacetates is enhanced. 7 8The application of this possible method of esterification of the cell wall components of (i) attempted esterification with halogenoalkylmonocarboxylic acids, in the hope of producing a measure of flame-retardant property in addition to dimensional stabilisation and (ii) attempted esterification with dicarboxylic acids to produce an ester-type cross-linkage between adjacent cellulose chains.By the latter method, with trifluoroacetic anhydride and dicarboxylic acid in a molar ratio of 2:1, cross-linkage would be expected to occur by acylation by a di-acylium ion. Thus :wood has been made on two different fronts, viz. :
The importance has been assessed of various factors responsible for the release of corrosive vapours from certain freshly‐felled hardwood and softwood species on exposure to high humidity and temperatures in excess of 30°. Variables studied include (i) season of felling, (ii) differences between sapwood and heartwood regions, (iii) initial acid content of the timber on felling, (iv) rǒle of non‐volatile extractive components in catalysing release of corrosive vapours and (v) inhibition of enzymic reactions by mild chemical sterilisation. Although the release of volatile acid is closely related to the loss of bound acetyl groups from the wood substance, indicating autohydrolysis of acetate in the cell wall material, the vapour corrosivity of a timber species is not directly related to its bound acetyl content. The presence of very small free acetic acid contents (0.01—0.03%) in some freshly‐felled undried woods is shown to play a significant rǒle in promoting rapid release of corrosive vapours by the woods (e.g., sweet chestnut and oak). Sterilisation of sweet chestnut and oak with propylene oxide vapour at ambient temperatures markedly reduces, but does not completely eliminate, release of corrosive vapours by these woods. An accompanying reduction in the proportion of bound acetate groups hydrolysed in the cell wall substance may indicate that the release of volatile acidic products from wood is in part due to a microbiological hydrolysis as well as chemical hydrolysis.
Changes in composition of volatiles released by freshly‐felled specimens of different softwood and hardwood species after incubation at sub‐tropical temperatures and high humidity have been determined by gas chromatographic and spectrophotometric techniques. A method is described for the isolation, identification and quantitative assay of organic acids, alcohols and esters released to atmosphere from selected wood species under certain exposure conditions. Sweet chestnut (Castanea sativa), oak (Quercus robur), wych elm (Ulmus glabra) and Douglas Fir (Pseudotsuga taxifolia) heart‐wood and wych elm sapwood all released significant quantities of acetic acid (1600‐550 p.p.m. of dried wood) and of formic acid (200‐40 p.p.m. of wood as dried) when incubated for 6 months at 48° and 100% R.H., but Norway spruce (Picea abies) and beech (Fagus sylvatica) heartwood and sapwood and Douglas Fir sapwood on the other hand released only small quantities of acids. The main neutral volatiles identified after incubation were methanol, methyl acetate, ethanol, formaldehyde and an unidentified component. Sterilisation of wood shavings with propylene oxide prior to incubation significantly reduced the concentrations of formic acid, acetic acid and methanol, with accompanying increases in ester concentration. This may be due to inhibition of enzymic hydrolysis of simple esters in sap fluids and of polymeric esters in the wood cell‐wall substance.
Procedures are described for converting primary amines into their well-crystalline trichloroacetyl-derivatives by treatment with hexachloroacetone under mild conditions. Although secondary aromatic N-methylamines are unaffected by hexachloroacetone, saturated heterocyclic amines react vigorously.A mechanistic study using 2-amino-4-t-butylthiazole showed that the reaction is first order in hexachloroacetone, second order in amine, and base-catalysed; there is no appreciable kinetic isotope (H/D) effect nor accumulation of intermediates during the reaction. A sequence which accommodates these results is suggested.N-SUBSTITUTED trichloroacetamides can be prepared by treating primary and secondary amines with trichloroacetyl chloride and primary amines with ethyl trichloroacetate,2 and, in low yield, by rearrangement of alkyl acet imidates .3 Some Nt richloroacet ylphen ylamines have also been obtained from the amines using aqueous hexachloroacetone; this ketone (in dimethyl sulphoxide) has been used for the trichloroacetylation of dipep tide^.^ The present work stemmed from the observation that 4-methyl-and 5-ethyl-2-trichloroacetamidothiazole, originally prepared using trichloroacetyl chloride,6 are formed readily from the 2-aminothiazoles and hexachloroacetone. A mechanistic investigation
A method for the determination of the fermentability of unboiled, filtered, malt Hot Water Extracts has been developed. The wort is fermented under carefully controlled conditions, using fresh dis tillers' yeast. Knowledge of a malt's extract and fermentability allows calculation of its fermentable extract content, which allows spirit yield prediction, and the method is in use as a basis for Malt Purchase Specifications.
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