E. Baciocchi

Dimethyl arylmalonates from cerium(IV) ammonium nitrate promoted reactions of dimethyl malonate with aromatic compounds in methanol

Abstract Aromatic compounds undergo homolytic malonylation by reaction with cerium(IV) ammonium nitrate and dimethyl malonate in methanol at room temperature.

The role of nitrate free radicals in the photochemical side-chain nitrooxylation of alkylbenzenes by cerium(IV) ammonium nitrate in acetonitrile

Abstract It is suggested that the reactive species in the CAN-induced photochemical side-chain nitrooxylation of alkylbenzenes is the nitrate radical, which probably acts as one-electron oxidant.

Photochemical nitrooxylation of methylbenzenes by cerium(IV) ammonium nitrate in acetonitrile

Abstract The photochemical reaction of substituted toluenes with CAN in CH 3 CN leads to good yields of benzyl nitrates under very mild conditions.

Oxidation of aromatic compounds by metal ions. Part 8. Structure and selectivity in anodic and metal ion oxidations of polyalkylbenzenes

Positional selectivity and the partition deuterium isotope effect (k/sub H//k/sub D/) have been determined in the chemical (with cerium(IV) ammonium nitrate (CAN), cobalt(III) acetate, and N-bromosuccinimide (NBS)) and electro-chemical side-chain oxidation of alkyl aromatics by using 5-R-hemimellitenes (R = H, t-Bu) and 1,3-dimethyl-2-(trideuterimethyl)-5-tert-butylbenzene as the substrates. Considering also the already available data for isodurene, it has been found that the positional selectivity is strongly influenced by the substrate structure in the anodic and CAN-promoted oxidations, both reactions exhibiting a very similar pattern. In conrast, Co(OAc)/sub 3/ selectivities do not correlate with those of the anodic oxidation but with the selectivities of the side-chain bromination promoted by NBS. These results have been interpreted by suggesting that, as in the anodic oxidations, CAN-induced reactions involve first the formation of a radical cation intermediate which then loses a proton to give a benzylic free radical in the selectivity-determining step. The data for Co/sup III/ would instead suggest a mechanism involving a hydrogen atom transfer, but this conclusion cannot yet be considered definitive. No simple correlation exists between selectivity data and the k/sub H//k/sub D/ values.

Cerium (IV) ammonium nitrate catalyzed photochemical autoxidation of alkylbenzenes

Abstract The autoxidation of alkylbenzenes can be promoted photochemically in the presence of catalytic amounts of cerim (IV) ammonium nitrate (CAN) under very mild conditions, the efficiency of the process being significantly increased by added acids. It is suggested that the reaction is promoted by NO 3 , radicals formed in the light induced decomposition of CAN and that Ce(III) may be reoxidized to Ce(IV) by benzylperoxy radicals.

Rate and mechanism for the reaction of the nitrate radical with aromatic and alkylaromatic compounds in acetonitrile

The results of a laser photolysis study indicate that an electron transfer process occurs in the reaction of the nitrate radical with aromatic and alkylaromatic compounds.

Relative reactivities of isopropyl, ethyl and methyl groups in the gas-phase side-chain deprotonation of alkylaromatic radical cations

Abstract The relative reactivity of isopropyl, ethyl and methyl groups in the gas-phase side-chain deprotonation of alkylaromatic radical cations by some pyridines has been determined by using Fourier transform mass spectrometry.

Dehalogenation reactions of vicinal dihalides. Part II. Substituent and leaving-group effects in the reactions of 1,2-dihalogeno-1,2-diphenylethanes with iodide, bromide, and chloride ions

The I–-, Br–-, and Cl–-promoted dehalogenations of several meso- or erythro-1,2-dibromo-1-(4-R1-phenyl)-2-(4-R2-phenyl)ethanes and the I–- and Br–-promoted dehalogenations of erythro-1-bromo-2-chloro-1,2-di-phenylethane have been investigated. The reactions with I– have been carried out in MeOH and dimethylformamide, those with Br– and Cl– in dimethylformamide. Both leaving-group and substituent effects indicate that these reactions occur by a completely concerted mechanism of elimination with a large amount of double bond developed in the transition state. It has been observed that the order of nucleophilic reactivity in dimethylformamide is I– > Br– > Cl–, which is consistent with an attack of the nucleophile on one bromine atom of the substrate. A peculiar result has been obtained in the case of the dinitro-derivative (R1= R2= NO2) which is, with Br– and Cl–, much more reactive than expected. A modification of the usual transition-state structure is probably required in this case.

Side-chain reactivity of indole derivatives. The reaction of 3-indolylmethyltrimethylammonium methyl sulphate with sodium toluene-p-thiolate

The reaction of 3-indolylmethyltrimethylammonium methyl sulphate with sodium toluene-p-thiolate in methanol is of first order in both reactants; the bimolecularrate constants, k2, decrease as the toluene-p-thiol concentration is increased. The plot of k2 against [p-CH3·C6H4·SH]–1 is linear. The results fit an elimination–addition mechanism of the type suggested for nucleophilic substitutions of gramine. This is supported by kinetic results for the corresponding reaction of 3-(N-methyl)indolymethyltrimethylammonium iodide.

Products, kinetics, and mechanism of the chlorination of 2,3-dimethylbenzothiophen in acetic acid

Chlorination of 2,3-dimethylbenzothiophen in acetic acid in the dark gives 2-chloromethyl-3-methylbenzothiophen quantitatively. The reaction is of zero order in the component which is in excess and of first order in the other. The rate and kinetic form remain unchanged in the presence of aromatic hydrocarbons which are extremely reactive towards chlorine. These facts can be explained if chlorine and 2,3-dimethylbenzothiophen interact rapidly to give an adduct which decomposes slowly to the products. The stability constant of this adduct is estimated to be >106 l. mole–1. The nature of the adduct and the reaction mechanism are discussed.