Acidic Aqueous Ethanol Research Articles

The molecular structure of 6‐(bromomethyl)‐1,2,4‐trichloro‐3‐ethoxy‐3,7,7‐trimethoxybicyclo[2.2.1] heptane; an X‐ray study

AbstractHydrolysis of 6‐(bromomethyl)‐ 1,2,4‐trichloro‐3,7,7‐trimethoxybicyclo[2.2.1] hept‐2‐ene with perchloric acid in aqueous ethanol yields inter alia the title compound. X‐ray analysis proved the positioning of the substituents to be 6‐endo‐(bromomethyl)‐2‐endo‐chloro,3‐endo‐ethoxy, which is evidence that the addition in this case follows an endo‐tram mechanism.The title compound crystallizes in the monoclinic space group P21/n with a = 10.504 Å, b = 10.507 Å, c = 15.783 Å, γ = 92.20° and Z = 4. The structure was solved by conventional techniques to an R = 0.063 using Mo(Zr) diffractometer data. The effect of the substitution on the conformation of the norbornane skeleton is discussed, as well as the geometry of the acetal groups in terms of the anomeric effect.

Synthesis of 4-(2-hydroxyethylsulfonyl)-1-naphthalenesulfonamide

This method of synthesis appears to be the more desirable because of the ease of purification of the product. 1-Naphthalenethiol(3) was converted to 2-(1-naphthylthio)ethyl acetate(5) via 2-(1-naphthylthio)ethanol(4) in an overall yield of 75%. Sulfonation of the ester 5 was carried out using 1 equiv of chlorosulfonic acid in dry chloroform to produce the 4-(2-acetoxyethylthio)-1-naphthalenesulfonic acid(6) which was isolated as the sodium salt(7) in 68% yield. The acetoxy acid chloride (8) was prepared from 7 in 68% yield. The reaction of 8 with excess ammonia in acetonitrile afforded an 89% yield of the desired sulfonamide(9), which was readily oxidized with m-chloroperoxybenzoic acid to the sulfone(10) in 84% yield. Hydrolysis of 10 with dilute hydrochloric acid in aqueous ethanol at 60/sup 0/C readily afforded pure HO--ENS in 95% yield. The compound was subjected to /sup 13/C NMR studies and thin-layer chromatographic analysis. 2 figures.

Addition des thiols sur les cetones—V: Effet de structure dans la réaction d'addition du mercapto-2-éthanol

Resume Rate constants for addition of 2-mercaptoethanol to seventeen ketones have been determined; all measurements were made in acidic aqueous ethanol 50 50 v v at 27.00±0.02°C. It is shown that the transition state occurs early along the reaction coordinate, the difference in reactivity arising mostly from steric hindrance to the appeoach of the nucleophile. The relative rate constants of addition of 2-mercaptoethanol are compared to those of other nucleophiles.

ChemInform Abstract: THE OXIDATION PRODUCTS OF 1‐ALKYL‐3‐ARYLTHIOUREAS‐ A CHEMICAL AND SPECTRAL STUDY

AbstractBei der Oxidation der Thioharnstoffe (I) mit H2O2 in saurer äthanolischer Lösung entstehen die Thiadiazolidine (II) und die Guanidine (III).

The oxidation products of 1-Alkyl-3-arylthioureas: A chemical and spectral study

The oxidation of 1-alkyl-3-arylthioureas with hydrogen peroxide in acidic aqueous ethanol yields 2,4-dialkyl-3,5-bis(arylimino)-1,2,4- thiadiazoles and N,N?-dialkyl-N?-aryl-N-benzothiazolylguanidines as the final products. The former were found to rearrange into the latter in acidic solutions. The formation of amidinothioureas as the precursors of thiadiazoles is established by their isolation from solutions which were partly oxidized. The reduction of the thiadiazole afforded an amidino-thiourea which was different from the one obtained by partial oxidation of thiourea. The reaction of benzenesulphonyl chloride on these thioureas also yielded amidinothioureas. The N.M.R. and mass spectra of the products obtained by the oxidation of these thioureas are also discussed briefly.

Proton and electron transfer in molybdenum complexes: Implications for molybdenum enzymes

The reaction of sodium molybdate with o-aminobenzenethiol in acidic aqueous ethanol leads to the isolation of Mo(SNHC 6H 4) 3, in which each coordinated amino group is singly deprotonated. This result, and others from the literature, are used to illustrate the change in the acidity of ligands coordinated to Mo as a function of both oxidation state and the number of bound oxo-groups. Thus, ligands which may be coordinated to Mo in enzymes may change their p K a values from less than to greater than the physiological pH as the oxidation state decreases. The Mo site may therefore have both proton and electron transfer capacity and since all substrate reactions involve the flow of both protons and electrons it is suggested that the Mo site couples the flow of electrons and protons. In line with this notion, simple mechanistic schemes are presented which explain a number of features of the action of Mo in enzymes. Analogies are drawn between Mo and Re chemistry and it is suggested that Re complexes and Re substituted enzymes (if and when prepared) may provide useful complementary information in the study of Mo chemistry.

Enolization and oxidation: II. Oxidation of ferrocene by molecular oxygen and hydrogen peroxide in acidic media

AbstractFerrocene can be oxidized by molecular oxygen in acidic aqueous ethanol. The rate is first order in oxygen and second order in ferrocene and in acid. Probably, hydrogen peroxide is an intermediate. This hydrogen peroxide is able to oxidize ferrocene and ferricenium ions, but the rates of these reactions are relatively slow. Hydrogen peroxide is removed mainly by reaction with the solvent ethanol. The latter reaction is catalyzed by small amounts of iron ions which originate from decomposition of ferrocene. The presence of this catalytic effect of iron ions in the reaction between hydrogen peroxide and solvent was shown in separate experiments.

A study of some benzeneseleninic acids; kinetics of reduction by iodide ion

The kinetics of the redox reaction of some para- and meta-substituted benzeneseleninic acids with iodide ion in acidic aqueous ethanol are reported. The acids are reduced to diaryl diselenides with the uptake of 3 equiv. of iodide ion. The reduction is of the first order in seleninic acid, iodide, and hydrogen ion. The rate constants at 25 ± 0·1°C for the H, p-Cl, p-Br, p-NO2, p-Me, m-Cl, m-Br, and m-NO2 derivatives are also reported.

Assoziation bei Azoverbindungen III: Untersuchung von 4‐Dimethylaminoazobenzol‐Derivaten in Lösung und in der Gasphase

Abstract(1) Spectrophotometric measurements at widely different concentrations in neutral and acidic aqueous ethanol (50% vol.) show that derivatives of 4‐dimethylaminoazobenzene are not associated under these conditions.