Thirty-one isomers of polychlorinated biphenyl (PCB) were examined for biodegradability by two species of Alcaligenes and Acinetobacter. The following relationships between chlorine substitution and biodegradability of PCBs were observed. (i) Degradation decreased as chlorine substitution increased. PCB isomers containing more than four chlorines were less susceptible to degradation. (ii) PCBs ...

Enzymatic and chemo-enzymatic approaches provide straightforward access to uridine diphospho sugars irrespective of the relative and absolute configuration of the sugar, its ring size and substitution pattern.

Variable scan rate (0.1-500 V s(-1)) cyclic voltammetry experiments were performed on a series of model tocopherol (vitamin E) compounds with differing degrees of methyl substitution around the aromatic (phenolic) ring. alpha-Tocopherol, with a fully methylated aromatic ring, produced stable phenoxonium cations upon oxidation in CH3CN, and was modeled via an ECE mechanism (where "E" represents ...

A strategy for the synthesis of the lycopodium alkaloid dihydrolycolucine (1) has been investigated. Synthetic routes were developed based on N-acylpyridinium salt chemistry to prepare target fragments 3 and 4 that could ultimately converge to the natural product. Key reactions include IMDA cycloadditions and retro-Mannich ring-openings to form both the AB and the EF ring fragments. The ring C ...

Better switching: The introduction of bulky substituents into the bridge moiety of dithienylethenes led to derivatives exhibiting high photocyclization quantum yields. This novel and versatile form of substitution facilitated tuning of the switching performance without compromising on the optical and redox properties of the ring-open and ring-closed forms (see scheme).

The liquid structure of the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate, [BMIM]PF(6), was investigated by neutron diffraction with H/D substitution method, where the hydrogen atoms in the imidazolium ring were partially deuterated. The local structures around the ring hydrogen atoms in liquid are very similar to those estimated from the crystal structure.

Specific deuterated reference compounds were prepared to probe the stereoselectivity of the reductive ring opening of carbohydrate-based benzylidene-type acetals. AlD(3) revealed a retentive stereoselectivity probably through the rare S(N)i (internal nucleophilic substitution) mechanism. An S(N)1-like mechanism occurs in the acid-promoted regioselective BD(3)·THF- or Et(3)SiD-reductive ring ope...

The title compound, C(16)H(25)NO(2)S, is a sulfonamide derivative with the substitution of propyl and cyclo-hexyl groups at the N atom. The least-squares plane through all six C atoms of the cyclo-hexyl ring forms a dihedral angle of 58.88 (12)° with the toluene ring. No hydrogen-bonding inter-actions are present in the crystal structure.

Numerous abused drugs of the 3,4-methylenedioxymetamphetamine (MDMA; Ecstasy; N-methyl-1-(3,4-methylenedioxyphenyl)-2-propaneamine) type and various alkyl chain- and aromatic ring-substituted isomers give very similar electron ionization (EI) mass spectra. This seriously affects the analysis of especially ring regioisomeric drug variants. Using collision-induced dissociation (CID) (argon) under...