The Preparation and Properties of Some α-Acyloxy- and α-Carbamoyloxy-Phosphonothionates

New f -acyloxy and f -carbamoyloxy derivatives of dimethyl 2,2,2-trichloroethyl-phosphonothionate have been prepared, characterized, and screened for activity against free-living soil nematodes. Several of the more easily hydrolysable esters, and also the N -methylcarbamoyl derivative, were as active as the parent pesticide, dimethyl f -hydroxy-2,2,2-trichloroethylphosphonothionate, after an induction period during which the active species is assumed to be released in vivo . It is concluded that the 2,2,2-trichloroethyl group is essential for activity in compounds of these types and that the presence of the N -methylcarbamoyl group does not in itself confer activity.     

Simple design flow injection PMMA acrylic sample cell for nitrite determination

A polymethyl-methacrylate(PMMA)acrylic sample cell using flow injection is developed in this research for the determination of nitrite in an aqueous media.The research focuses on exhibiting direct absorbance spectrophotometry of nitrite using concentration of samples ranging from 0.1078 to 1.725 ppm.Nitrite determination is done colorimetrically using the Greiss reagent method.This method is based on the reaction of nitrite with sulphanilamide acid and N-1-napthylamine(NED)utilizing diazo coupling,and a syringe is used to administer the nitrite solution.The sample cell being used possesses a diameter of 1mm with an overall size of 7.35×22 mm2.To gauge the direct absorbance,a wavelength range from 400to 650 nm has been selected for the testing,and the maximum absorbance is found to be at 545 nm.The validity of the proposed cell is explained in this letter.     

Effect of magnetic pore surface coating on the NMR relaxation and diffusion signal in quartz sand

Magnetic impurities are ubiquitous in natural porous media such as sand and soil. They generate internal magnetic field gradients because of increased magnetic susceptibility differences between solid and liquid phase in the pore space and because of the presence of magnetic centers. These internal gradients accelerate NMR relaxation rates and thus might limit the possibility of pore space characterization using NMR. In this study, we investigate the effects of coating the surface of natural sands by the antiferromagnetic iron oxyhydroxide goethite on NMR relaxation and diffusion properties. We found a non‐quadratic dependence of the relaxation time distributions on the echo time indicating that the relaxation experiments were not performed in the fast diffusion limit, while the weak dependence on the external magnetic field strength is explained by the preponderance of the surface relaxation over the effect of diffusion in internal gradients. The surface to volume ratio of the pore space, determined by NMR diffusimetry ((S/V)_NMR) remains approximately constant, whereas the same quantity, determined from gas adsorption ((S/V)_BET) increases proportional to the coating density. This is because gas adsorption measures surface roughness on sub‐nanometer scale, whereas NMR diffusimetry averages over structures smaller than few microns. This has consequences for the calculation of the surface relaxivities. The usage of the (S/V)_NMR leads to constant values, whereas the usage of (S/V)_BET leads to apparently decreasing relaxivities with increasing coating, which is unrealistic. Copyright © 2016 John Wiley & Sons, Ltd.     

Diels–Alder reactions and transformations of 2-cyclopenten-1-one with a chiral anthracene template

Excellent regio- and diastereoselectivity were achieved in the microwave assisted Diels–Alder reaction between (S)-9-(1-methoxyethyl) anthracene and 2-cyclopenten-1-one. The addition of Grignard reagents to the ketone cycloadduct gave poor levels of diastereoselectivity, however, the reduction was significantly more stereoselective. Flash vacuum pyrolysis of the reduced material furnished the corresponding allylic alcohol in good yield and ee.