Effect of intermolecular synergy in inhibiting action of 1-phenacylmethylpyridinium halides

The intermolecular synergy effect of 1-phenacylmethylpyridinium halides on steel corrosion in 3 M H2SO4 solutions was studied.     

Intermolecular effect in molecular electronics

We investigate the effects of lateral interactions on the conductance of two molecules connected in parallel to semi-infinite leads. The method we use combines a Green function approach to quantum transport with density functional theory for the electronic properties. The system, modeled after a self-assembled monolayer, consists of benzylmercaptane molecules sandwiched between gold electrodes. We find that the conductance increases when intermolecular interaction comes into play. The source of this increase is the indirect interaction through the gold substrate rather than direct molecule-molecule interaction. A striking resonance is produced only 0.3 eV above the Fermi energy.     

Simple synthesis ofβ-silyloxyacylcyclopropanes and the homoallyl rearrangement of cyclopropylcarbinols by the action of trimethylsilyl halides in the presence of zinc halides

The ZnCl₂ catalyzed condensation of 1-trimethylsilyloxyvinylcyclopropane with aldehydes and ketones gave -silyloxyacylcyclopropanes, which were converted by the action of TsOH in boiling benzene into 1-cyclopropyl-2E-alken-1-ones. Reduction of the latter gave saturated and allyl cyclopropylcarbinols, which by means of Me₃SiX and catalytic amounts of ZnX₂ (X=Cl, Br) were highly selectively converted into the corresponding linear mono- and dienic E-homoallyl halides. The sequence of reactions that was worked out provided an effective synthesis of 3E-dodecenyl acetate, a sex pheromone of the sugar beet moth.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2025–2036, September, 1990.     

Transformation of 4-nitrobenzyl halides at the action of phosphinates and carboxylic acids orthoesters

Russian Journal of General Chemistry -     

Temperature and concentration dependence of the activity of quinones of presumed inhibiting action

The inhibiting properties of a series of organic compounds with a quinonoid structure have been electrochemically studied. The effect of the area and the structure of the organic molecule on the activity of the quinones has been followed. The compounds studied inhibit mild steel's corrosion in model cooling water and prove to be inhibitors of a cathodic type. The degree of corrosion inhibition is a function of the temperature, the concentration and the nature of the substance. The protective effect of the quinones is explained with their adsorption on the corroding surface. The adsorption itself is facilitated by the presence of π-electron systems and conjugated bonds in the molecules as well as by the increase of the molecule's size. Some differences in the behaviour of the p- and o-compounds studied are observed.     

Rhenium,part XIV. Studies on the action of hydrogen halides on [ReO2en2]+

Summary The products from the reaction oftrans-dioxobis(ethylenediamine)rhenium(V) halides with hydrogen halides have been investigated. Dilute (2M) and concentrated hydrochloric acid react with (ReO₂en₂)Cl in the cold to give ReO(OH)enCl₂ and IRe(OH)₂enCl₂]Cl respectively, while with hot 6M HCl [ReOCl₅]^2– is formed. Dilute solutions of HX protonate [ReO₂en₂]X (X = Br and I) giving [ReO(OH)en₂]X₂ which are converted slowly into ReO(OH)enBr₂ and [ReO(OH)en2](I₃)₂. Hot and concentrated solutions of HX reduce Re^v in (ReO₂en2 )X (X = Br and I) giving enH₂(ReBr₆) and ReI₄en. The thermal decomposition of (ReO₂en₂)X (X = Cl, Br and I) has been studied by thermogravimetry and a polymeric compound, Re₂O₇en₂, has been isolated by heating (ReO₂en₂)X at 200°. The compounds have been characterised by molecular conductivities, magnetic susceptibility and i.r. spectra.     

The inhibiting effect of catecholamine-melanins on UV-induced lecithin peroxidation.

It was found that the yield of thiobarbituric acid reactive substances in UV-irradiated liposome membranes was significantly suppressed in the presence of catecholamine-melanins, indicating their ability to inhibit lipid peroxidation. The extent of inhibition depended on the type and concentration of melanin polymers. Melanin-copper complexes inhibited lecithin photooxidation less effectively than copper-free melanins derived from the same precursor. The antioxidant efficiency of melanins appears to be related to the levels of intrinsic and photo-induced free radical centers in the melanin polymer, as well as to accessibility of these centers for active species formed during irradiation of liposomes.