Anthony H. Conner

Predicting the reactivity of phenolic compounds with formaldehyde under basic conditions: An ab initio study

A method is needed to predict which compounds, from the many alternative phenolic compounds, might be best for making polymeric phenolic systems. Kinetic data for the reaction of a series of phenolic compounds with formaldehyde using a base catalysis are available in the literature. Semiempirical calculations, using RHF/PM3, and ab initio calculations, using RHF/6-31G, RHF/6-31+G, and B3LYP/6-311+G(2d,p), were performed on the series of phenolic compounds to determine their relative reac- tivities. Atomic charges were determined for the phenolate anions. For each compound, I summed the absolute value of the calculated, negative charges residing on carbon atoms of the phenolic ring at which the HOMO was located and at which no substituent was present to cause steric interference with the reaction. The sum of the charges for each compound was then regressed against the log of the relative reaction rate for that compound. The sum of charges from PM3-based calculations gave poor correlation with reactivity. The sums of charges calculated by the CHelpG and Merz-Kollman/Singh methods at the ab initio levels of theory give excellent correlations with reactivity of the phenolics toward formaldehyde. Based on the calculated charges, estimates of the relative reactivity at each of the reactive sites on each of the phenolic compounds were determined.

The reversion reactions of d-glucose during the hydrolysis of cellulose with dilute sulfuric acid

Abstract The reversion products formed during the acid hydrolysis of Avicel to d -glucose, under conditions envisaged for the industrial conversion of woody biomass into monomeric sugars, have been determined by using gas-liquid chromatography. Avicel was hydrolyzed in dilute sulfuric acid (0.26–1.27 wt.%) between 160 and 250° in small (3 mm, i.d.) glass tubes at a 3:1 liquid-to-solid ratio. The anhydro sugars, levoglucosan and 1,6-anhydro-β- d -glucofuranose, were produced in the ratio of 7:3 and ocnstituted > 50% of the total yield of reversion products. The yield of anhydro sugar followed equilibrium kinetics, and reached 6% at maximum yields (50%) of d -glucose. Isomaltose and gentiobiose were the most preponderant disaccharides found among the reversion products, constituting together ∼25% of the reversion products. The (1→2)- and (1→3)-linked α-disaccharides preponderated over their β counterparts. The total yields of reversion products approached 10% on the basis of the d -glucose theoretically available.

Effects of aqueous sulfur dioxide on cellulose

SummaryThe reaction of aqueous sulfur dioxide with cellulose pulp and cotton linters was investigated to determine the effect of this lignocellulosic pretreatment method on the cellulosic portion. Sulfur dioxide treatment dramatically reduced the DP of the cellulose but did not affect its enzymatic digestibility, and did not decrystallize the cellulose as recently reported by Leeet al. (1979).

Phenolation of (+)-catechin with mineral acids. II. Identification of new reaction products

Abstract To investigate the reactions that occur in the flavanoid unit during the liquefaction of tannin in phenol, the phenolysis of (+)-catechin was studied using either H2SO4, HCl, or BF3 2H2O as acid catalyst. In addition to 2-[3-(3,4-dihydroxyphenyl)-2-hydroxy-3-(4-hydroxyphenyl)propyl]-1,3,5-benzenetriol (1) and 2-[(3,4-dihydroxyphenyl)(4-hydroxyphenyl)methyl]-2,3-dihydro-4,6-benzofurandiol (3) that have been described previously, eight additional reaction products were isolated, four of which were compounds that have not been described previously. The novel compounds described here are: 2-[3-(3,4-dihydroxyphenyl)-2-hydroxy-3-(2-hydroxyphenyl)propyl]-1,3,5-benzenetriol (2), 2-[(3,4-dihydroxyphenyl)(2-hydroxyphenyl)methyl]-2,3-dihydro-4,6-benzofurandiol (4), 2-[(3,4-dihydroxyphenyl)(4-hydroxyphenyl)methyl]-2,3-dihydro-7-(4-hydroxyphenyl)methyl-4,6-benzofurandiol (5), and 2-(1,3,5-trihydroxyphenyl)methyl-3-(3,4-dihydroxyphenyl)-6-[(3,4-dihydroxyphenyl)(4-hydroxyphenyl)methyl]-2,3,5,6-tetrahydrobenzo[1...