The present paper is intended as a contribution to the specific chemistry of the naturally occurring hydroxyamino acids. Certain established differences in the chemistry of the acyl derivatives of amino and hydroxy groups have so far not been utilized in the study of hydroxyamino acids, and in particular no simple method for the preparation of their 0-acetyl derivatives has been developed. The ...

The aim of this study was to improve enteric properties of shellac by the formation of succinate derivative through dry media reaction. Shellac and succinic anhydride were mixed and then co-ground by planetary ball mill. The ground mixture was then activated by heating for various times and washed for removal of excess succinic anhydride. The ground mixtures and the heat-activated mixtures were...

The mechanisms and kinetics of unimolecular decomposition of succinic acid and its anhydride have been studied at the G2M(CC2) and microcanonical RRKM levels of theory. It was shown that the ZsgsZ conformer of succinic acid, with the Z-acid form and the gauche conformation around the central C-C bond, is its most stable conformer, whereas the lowest energy conformer with the E-acid form, ECGsZ,...

The difructose anhydrides include four welldefined crystalline sugars. Diheterolevulosan was first prepared by Pictet and Chavan [1]l by the action of concentrated hydrochloric acid on fructose at 0° C. This sugar is a difructopyranose in which carbon atoms 1 and 2 of each fructose residue are joined to form a dioxane ring. The other members [2,3] of this group arc designated difructose anhydri...

As shown in the previous paper, a metabolite of thiamine anhydride (TA) (I) was isolated as crystals melting at 172-173•‹ from the urine when TA was given parenterally to rats and it was assumed to be thiamine anhydride sulfoxide (TAO) (II) from its analytical data. It is known, however, that TA can be oxidized to TA sulfone (III) besides its sulfoxide by hydrogen peroxide according to the con ...

INTRODUCTION The inability of acetic anhydride to acetylate pulp efficiently in the absence of a catalyst has received much attention from different research workers. In fact the acetylation with acetic anhydride is unsuccessful if pre-activation has not been carried out. It can be assumed that the energy of interaction between acetic anhydride and cellulose in the absence of a catalyst is insu...

The present paper is intended as a contribution to the specific chemistry of the naturally occurring hydroxyamino acids. Certain established differences in the chemistry of the acyl derivatives of amino and hydroxy groups have so far not been utilized in the study of hydroxyamino acids, and in particular no simple method for the preparation of their 0-acetyl derivatives has been developed. The ...

Only one case report concerning allergic alveolitis caused by polyester powder paint has been published previously. The aim of this study was to determine whether phthalic anhydride (PA) or trimellitic anhydride (TMA) is the alveolitis-causing agent in such paint. A 61 year old woman showed recurrent symptoms of chills, cough, and fever whilst at work. She was working in a plant where epoxy pol...

Lattice energy calculations using a model potential were performed to model the crystal structures of cis-1,2,3,6- and 3,4,5,6-tetrahydrophthalic (THP) anhydrides. The optimized molecular models using the DFT method at the B3LYP/6-31G** level were found consistent with the available experimental evidence and allowed all differences observed in crystal packing between cis-1,2,3,6- and 3,4,5,6-TH...

An efficient method to improve the mechanical performance of a commercially available photocure resin is described wherein modified with mixture cycloaliphatic epoxy and an anhydride curing agent. Photocured samples are thermally treated in subsequent step cure obtain interpenetrated polymer network (IPN) also complete reaction acrylate monomers remaining from photocure. The latter accomplished...