2—甲基—2—甲氧基羰基—5—次甲基—1,3—二氧环戊—4—酮的合成和阴离子聚合

本文报导了一种环状新单体，２－甲基－２－甲氧基羰基－５－次甲基－１，３－二氧环戊－４－酮的合成，并用红外、核磁及元素分析对单体和中间体的结构进行了鉴定．在－７０℃及干燥氮气保护下，用９－芴锂作阴离子５：发剂对此新单体进行了阴离子开环聚合反应的研究．聚合物的红外和核磁谱图表明：在聚合物中存在两种结构单元，这说明在聚合过程中同时存在开环和不开环的两种情况。虽然在聚合物中，这两种结构单元的量应取决于两种相应的碳阴离子的相对稳定性，但是开环聚合在热力学上是有利的，因为开环的结果形成了更稳定的羰基．用粘度法测定了聚合物的特性粘数。     

Stability of selected volatile contact allergens in different patch test chambers under different storage conditions

Background. Patch test preparations of volatile substances may evaporate during storage, thereby giving rise to reduced patch test concentrations. Objectives. To investigate the stability of selected acrylates/methacrylates and fragrance allergens in three different test chambers under different storage conditions. Methods. Petrolatum samples of methyl methacrylate (MMA), 2‐hydroxyethyl methacrylate (2‐HEMA), 2‐hydroxypropyl acrylate (2‐HPA), cinnamal and eugenol in patch test concentrations were stored in three different test chambers (IQ chamber?, IQ Ultimate?, and Van der Bend® transport container) at room temperature and in a refrigerator. The samples were analysed in triplicate with high‐performance liquid chromatography. Results. The decrease in concentration was substantial for all five allergens under both storage conditions in IQ chamber? and IQ Ultimate?, with the exception of 2‐HEMA during storage in the refrigerator. For these two chamber systems, the contact allergen concentration dropped below the stability limit in the following order: MMA, cinnamal, 2‐HPA, eugenol, and 2‐HEMA. In the Van der Bend® transport container, the contact allergens exhibited acceptable stability under both storage conditions, whereas MMA and 2‐HPA required cool storage for maintenance of the limit. Conclusion. The Van der Bend® transport container was the best device for storage of samples of volatile contact allergens.     

Occupational allergic contact dermatitis and contact urticaria caused by polyfunctional aziridine hardener

Polyfunctional aziridine (PFA) is increasingly used as a water-based cross-linker in 2-component paints, paint primers, lacquers, topcoats and other protective coatings. The cross-linker (PFA hardener) is made by reacting multifunctional acrylic monomer with a highly reactive aziridine compound. During 1992–1993, we came across 2 patients with allergic patch test reactions provoked by PFA hardener. One of the patients was a parquet layer, and the other a printer. Allergic-contact dermatitis (ACD) was diagnosed by positive allergic patch test reactions to PFA hardener in a dilution series in pet.: 0.3%-1% gave ++ to +++ allergic reactions in both patients, whereas 0.1% gave a weak (+) or questionable reaction (?+), respectively. The methacrylate patch test series was negative in both patients, although gas chromatography mass spectrometry analysis showed that PFA hardener contained 0.3% of trimethylolpropane triacrylate (TMPTA), a multifunctional acrylic monomer. One of the patients also had symptoms of contact urticaria, and a prick test with PFA hardener (1% aq.) induced a histamine-sized prick test reaction. The positive reactions with the PFA hardener and the negative reactions with the starting chemicals and additives in PFA, namely acrylates, propyleneimine and dimethylethanolamine, indicate that PFA caused ACD. This is in accordance with our previous observations, but differs from the reports of others, whose patients had been sensitized to acrylates present as remnants in the PFA hardener. As test substance, 0.5% PFA hardener in pet, is recommended for patch testing. Testing should be performed in patients with contact dermatitis if exposure to PFA has occurred. Skin prick tests may be of help to detect contact urticaria.     

Outperformance in Acrylation: Supported D-Glucose-Based Ionic Liquid Phase on MWCNTs for Immobilized Lipase B from Candida antarctica as Catalytic System

This study presents a highly efficient method of a synthesis of n-butyl acrylate via esterification of acrylic acid and n-butanol in the presence of supported ionic liquid phase (SILP) biocatalyst consisting of the lipase B from Candida antarctica (CALB) and multi-walled carbon nanotubes (MWCNTs) modified by D-glucose-based ionic liquids. Favorable reaction conditions (acrylic acid: n-butanol molar ratio 1:2, cyclohexane as a solvent, biocatalyst 0.150 g per 1 mmol of acrylic acid, temperature 25 °C) allowed the achievement of a 99% yield of n-butyl acrylate in 24 h. Screening of various ionic liquids showed that the most promising result was obtained if N-(6-deoxy-1-O-methoxy-α-D-glucopyranosyl)-N,N,N-trimethylammonium bis-(trifluoromethylsulfonyl)imide ([N(CH₃)₃GlcOCH₃][N(Tf)₂]) was selected in order to modify the outer surface of MWCNTs. The final SILP biocatalyst–CNTs-[N(CH₃)₃GlcOCH₃][N(Tf)₂]-CALB contained 1.8 wt.% of IL and 4.2 wt.% of CALB. Application of the SILP biocatalyst led to the enhanced activity of CALB in comparison with the biocatalyst prepared via physical adsorption of CALB onto MWCNTs (CNTs-CALB), as well as with commercially available Novozyme 435. Thus, the crucial role of IL in the stabilization of biocatalysts was clearly demonstrated. In addition, a significant stability of the developed biocatalytic system was confirmed (three runs with a yield of ester over 90%).