James Bouquant

Guaianolides from the leaves of Centaurea incana

Abstract Six guaianolides have been isolated from the aerial parts of Centaurea incana from Algeria. They were identified as desoxyrepin, repin or subluteolide, repin monochlorhydrin, acroptilin, janerin and repdiolide triol.

1H‐NMR for the safety control of food packaging materials: Analysis of extracts from polyolefin samples

A new approach for the identification of the additives in extracts of packaging plastics, using proton nuclear magnetic resonance (1H-NMR), is presented. The technique can be used in a preliminary step for the determination of contaminants potentially released by the food packaging materials; it may greatly reduce the time required to identify the constituents of the materials, either individually or as functional classes. A classification of the EEC additives is proposed on the basis of chemical shift. 1H-NMR can also be used as a fingerprint technique in the quality control of the food packaging materials.

Quick methods to control compliance of plastic materials with food packaging regulations

A general strategy is presented, aiming to provide plastics manufacturers, food industries and enforcement laboratories with quick methods to check whether migration from materials for food contact will be acceptable during the time of use. The strategy involves several steps, with increasing time demand and cost. Monitoring extraction kinetics allows both the optimization of the extraction time, and the selection of conditions where extraction is more severe than migration. The influence of the extracting solvent is discussed. It may give rise to specific non-extraction of some migrants, which may change the conclusions when the solvent is used in replacement of a fatty food simulant. Factors ruling this effect at a given temperature are identified: the affinity to the solvent with the migrant (selectivity), its ability to reach molecules entangled in the polymeric network (accessibility) and its interaction with the polymer (penetration). The kinetic parameters of the penetration of olive oil into polypropylene have been determined by the determination of profiles of concentration.

Preparation of 3-azabicyclo [3.2.0] heptenones by intramolecular [2+2] cycloaddition

Abstract Pyrolysis of N-allyl enaminoesters is a general method for the stereoselective synthesis of 3-azabicyclo[3.2.0] heptenones ; the reaction involves a [2+2] intramolecular cycloaddition of an intermediate iminoketene.

Alternative test methods to control the compliance of polyolefin food packaging materials with the European Union regulation: The case of aromatic antioxidants and of bis(ethanolamine) antistatics based on 1H‐NMR and UV‐visible spectrophotometry

In order to decide whether a plastic food packaging material complies with the European Communities (EC) regulation on migration, a quick analysis of two functional classes of plastics additives (aromatic antioxidants and antistatic agents) from polyolefin materials by 1H-NMR and UV-visible spectrophotometry is presented. The scope of spectroscopic methods for alternative and migration tests is presented. 1H-NMR can be used in several ways, from a simple fingerprint of the potential migrants to an identification procedure. Extraction is optimized using UV spectrophotometry. Optimization relies on extraction kinetics, which include the demonstration that extraction is more severe than migration. Only a few hours are required to conclude whether a material complies with the regulation. The specific migration limits are expressed as specific absorbance limit values, alpha. These data can be annexed by food industries to specifications of a plastic packaging material.

Selective formation of aminoxyls or oxaziridines by oxidation of 2,2,4,4-tetrasubstituted oxazolidines

Abstract The reactivity of 2,2,4,4-tetrasubstituted-1,3-oxazolidines 1 with m-chloroperbenzoic aicd was reinvestigated. Aminoxyls 5 are isolated in good yields in ether at −15 °C, or in anhydrous dichloromethane at 0 °C. Oxaziridines 4 are promoted at room temperature, or in the presence of an acid. In any case, short reaction times prevented the degradation of aminoxyls and oxaziridines. The competition between oxaziridines 4 and aminoxyls 5 is ruled by the oxazolidine imine equilibrium.

A simple stereochemical assignment of 1,4-diols having a cis-2,3-methano bridge

A convenient and reliable method, based on derivatization and NMR, allows for the assignment of the relative stereochemistry in various substituted cis-1,2-bis(hydroxymethyl)cyclopropanes.

Nuclear magnetic resonance lanthanide-shift regents: conformational analysis of 1-methylcyclohexanol

Results of the conformational study of 1-methylcyclohexanol with Eu(dpm)3 are in agreement with a conformational equilibrium shift of the complexed molecule compared to the free one.