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Aryl Esters (aryl + ester)

Distribution by Scientific Domains
Chemistry75%

Selected Abstracts

ChemInform Abstract: Pd-Catalyzed Decarbonylative Olefination of Aryl Esters: Towards a Waste-Free Heck Reaction.

CHEMINFORM, Issue 34 2002
Lukas J. Goossen
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

UV/Vis to NIR Photoconduction in Cyclopalladated Complexes

CHEMISTRY - AN ASIAN JOURNAL, Issue 7 2009
Nicolas Godbert
Abstract Funky discotics: Photoconductivity is measured in newly synthesized cyclopalladated metallomesogens exhibiting hexagonal columnar mesophases at room temperature. The tuning of the HOMO/LUMO energy levels by modification of the chain/core linkage (ester 1 vs ether 2) makes compound 2 photoconductive across the whole UV/Vis/NIR range. The incorporation of a rigid core, formed by a cyclopalladated azobenzene fragment bonded to an ancillary Schiff base ligand, into molecules with 12 or 11 peripheral alkyl chains has been successfully achieved. These new complexes, 1 and 2, respectively, are columnar liquid crystals between room temperature and about 50,°C. Both cyclometallated and ancillary ligands have been polyalkylated through either aryl ester (electron-withdrawing group) or aryl ether (electron-releasing group) linkages, in order to tune the HOMO/LUMO energy levels. The photoconductive properties of 1 and 2 have been studied as a function of their absorption properties before and after annealing, from the UV/Vis to NIR region. Compared with the reference compounds, tris-alkynyl benzene discotics, these new materials gave similar performances (,/I,8×10,13,S,cm,W,1 with E=10,V,,m,1 at ,=370,nm). Moreover, complex 2 shows a normalized photoconductivity ,/I=8.5×10,13,S,cm,W,1 at ,=760,nm. Organic photoconductors in such a high wavelength spectral range are not common and are usually assembled by mixing dyes with organic semiconductors. [source]

ChemInform Abstract: Organocatalytic Asymmetric Intramolecular [3 + 2] Cycloaddition: A Straightforward Approach to Access Multiply Substituted Hexahydrochromeno[4,3-b]pyrrolidine Derivatives in High Optical Purity.

CHEMINFORM, Issue 38 2010
Nan Li
Abstract A chiral dinaphthyl-BINOL-derived phosphoric acid (NABIP) efficiently catalyzes the asymmetric intramolecular cycloaddition of formylphenoxybutenoates (I) and (IV) in the presence of ,-amino-,-aryl esters (II). [source]

Phthalate Esters in Foods: Sources, Occurrence, and Analytical Methods

COMPREHENSIVE REVIEWS IN FOOD SCIENCE AND FOOD SAFETY, Issue 1 2010
Xu-Liang Cao
ABSTRACT:, Phthalates are a group of diesters of ortho-phthalic acid (dialkyl or alkyl aryl esters of 1,2-benzenedicarboxylic acid). Higher-molecular-weight phthalates, such as di-2-ethylhexyl phthalate (DEHP), are primarily used as plasticizers to soften polyvinyl chloride (PVC) products, while the lower-molecular-weight phthalates, such as diethyl phthalate (DEP), di-n-butyl phthalate (DBP), and butyl benzyl phthalate (BBzP), are widely used as solvents to hold color and scent in various consumer and personal care products. Phthalates have become ubiquitous environmental contaminants due to volatilization and leaching from their widespread applications, and thus contamination of the environment has become another important source for phthalates in foods in addition to migration from packaging materials. Human exposure to phthalates has been an increased concern due to the findings from toxicology studies in animals. DEHP, one of the important and widely used phthalates, is a rodent liver carcinogen. DEHP, DBP, BBzP, and several phthalate metabolites, such as monobutyl phthalate, monobenzyl phthalate, and mono-(2-ethylhexyl) phthalate, are teratogenic in animals. Since foods are the major source of exposure to phthalates, information on levels of phthalates in foods is important for human exposure assessment. The objective of this review is to identify the knowledge gaps for future investigations by reviewing levels of a wide range of phthalates in a variety of foods, such as bottled water, soft drinks, infant formula, human milk, total diet foods, and others, migration of phthalates from various food-packaging materials, and traditional and new methodologies for the determination of phthalates in foods. [source]