Morton Raban

Studies of the hydrolysis of 14C-labeled tetraethoxypropane to malondialdehyde.

1,1,3,3-[1,2,3-14C]Tetraethoxypropane has been subjected to acid-catalyzed hydrolysis and the [1,2,3-14C]malondialdehyde produced was quantitated following chromatography on Sephadex G-10. At initial concentrations of tetraethoxypropane of 1, 10, and 100 m m , malondialdehyde constitutes 77, 80, and 78%, respectively, of the material eluting from the columns. The malondialdehyde has been identified by its chromatographic behavior and by uv and NMR spectroscopy. Two different procedures are given for the preparation of crystalline sodium malondialdehydate.

Thermodynamic asymmetric induction: a new approach to the development of rules for the determination of absolute configurations

Abstract The absolute configurations of chiral primary amines can be determined using the optical rotations of the corresponding N-p-toluenesulfonyl-N-2,4-dinitrobenzensulfenyl derivatives.

A sterically switched ionophore

Abstract A cyclohexane pro-ionophore is held in one chair form (non-ionophoric) by a large, tertiary, ketal moeity. Upon hydrolysis the acetyl group is small enough to be axial and the cyclohexane ring can flip to an ionophoric conformation.

Alkali metal chelation by diacetamide

Abstract Proton NMR spectroscopy indicates that diacetamide exists as an equilibrium mixture of Z,Z and E,Z diastereomers in methanol solution. Addition of Lil, Na1 or K1 (configurational titration) shifts the quilibrium because of bidentate complexation (chelation) by the amide carbonyl oxygens.

Stereochemistry in trivalent nitrogen compounds. 40. Torsional barriers in N-2,4-dinitrobenzenesulfenylbenzimidazoles.

Abstract N-2,4-Dinitrobenzenesulfenylbenzimidazoles exhibit substantial barriers to torsion about the sulfur-nitrogen bond ( ca 19 kcal/mole).

MASS SPECTRAL FRAGMENTATION OF DISULFENAMIDES

Abstract Five disulfenamides were prepared by reaction of benzylmethylamine and benzyliso-propylamine with sulfur chlorides, (RSR, RSSR and RSSSR, R = C6H5CH2NCH3 or R = C6H5CH2NCH(CH3)2). Their mass spectra are presented and discussed.

THE SULFENAMIDE CHIRAL UNIT. TORSIONAL BARRIERS IN TRINITROBENZENESULFENAMIDES AND PERHALOBENZENSULFENAMIDES

Abstract The free energies of activation for degenerate racemization of sulfenamides, measured by DNMR spectroscopy provide information about the N-S formal single bond since stereomutation is accomplished by torsion about this bond. The S-N torsional barrier in benzenesulfenamides (arSNR1R2) is singnificantly increased by the presence of substituents which are electron withdrawin (by resonance). However, while the barrier is increased by para anda/single ortho substituent, the introduction of a second ortho substituent lowers the barrier.