Probable Reaction Pathways Research Articles

Terpene amines. IV. Synthesis and study of the structure of amines from d-fenchone

The reductive amination of d-fenchone by aliphatic nitriles has been studied. A probable reaction pathway is suggested, and the stereochemical composition of the products has been determined. It has been established with the aid of13C NMR that the reaction forms a mixture of isomeric optically active N-alkyl-1,3,3-trimethylbicyclo[2.2.1]hept-2-ylamines with a 3:1 ratio of endo and exo isomers. The absolute configurations of the amines synthesized have been determined.

ChemInform Abstract: ABSOLUTE RATE CONSTANTS FOR THE HYDROXYL RADICAL REACTIONS WITH ETHANE, FURAN, AND THIOPHENE AT ROOM TEMPERATURE

Interests in the gas phase oxidation of heterocyclic organic compounds containing oxygen, nitrogen, or sulfur have become increasingly evident due to the important roles that these compounds may play in combustion processes, atmospheric chemistry, and photochemical air pollution. The rate constants for the reactions of OH with furan (C4H4O) and thiophene (C4H4S) have been determined for the first time under pseudo‐first‐order conditions, using the discharge flow‐resonance fluorescence technique. The measured room temperature rate constants are (2.31±0.40)×10−13, (1.05±0.08)×10−10, and (4.77±0.63)×10−11 cm3/molecule−1 s−1 for ethane, furan, and thiophene, respectively. The results are discussed in terms of structural differences and probable reaction pathways.

Absolute rate constants for the hydroxyl radical reactions with ethane, furan, and thiophene at room temperature

Interests in the gas phase oxidation of heterocyclic organic compounds containing oxygen, nitrogen, or sulfur have become increasingly evident due to the important roles that these compounds may play in combustion processes, atmospheric chemistry, and photochemical air pollution. The rate constants for the reactions of OH with furan (C4H4O) and thiophene (C4H4S) have been determined for the first time under pseudo-first-order conditions, using the discharge flow-resonance fluorescence technique. The measured room temperature rate constants are (2.31±0.40)×10−13, (1.05±0.08)×10−10, and (4.77±0.63)×10−11 cm3/molecule−1 s−1 for ethane, furan, and thiophene, respectively. The results are discussed in terms of structural differences and probable reaction pathways.

Study of interfacial kinetics for liquid-liquid systems—II: Intrinsic kinetics of the copper chelation reaction with an oxime-based reagent

The interfacial chelation of copper from copper sulfate-sulfuric acid solutions by the commerical oxime extractant LIX65N in toluene is studied using the liquid jet recycle reactor. The intrinsic initial rate of copper chelation by LIX65N is found to be represented in mol. cm −2-sec −1 by the expression R = 1.22 × 10 −8{Cu 2+}[LIX65N] {H +} + 0.0288[LIX65N] where {Cu 2+} and {H +} are the cupric and hydrogen activities. The interfacial rate expression above is determined as free from diffusional contributions by using a numerical solution to model mass transfer with interfacial reaction in the LJRR. The above expression is selected on statistical and physical grounds from a set of models systematically generated from the most probable reaction pathways. The liquid jet technique has been shown to be an effective and accurate (±6% experimental error) technique for the study of liquid-liquid interfacial reactions.

The preparation, characterisation and some reactions of Os3(CO)9(μ2-H)(μ3-SR) (R  Me or Et)

Abstract The complex Os 3 (CO) 9 (μ 2 -H) 2 (μ 3 -S) reacts with KOH/MeOH to produce the anionic complex [Os 3 (CO) 9 (μ 2 -H)(μ 3 -S) − , which reacts in turn with RO + (R = Me, Et) to form HOs 3 (CO) 9 SR. This complex is especially reactive towards ligands L (L = C 2 H 4 , CO, PR 3 and MeCN) to generate complexes of the type Os 3 (CO) 9 (μ 2 -H)(μ 2 -SR)(L). At 125°C the complex Os 3 (CO) 9 (μ 2 -H)(μ 2 -SR)(C 2 H 4 ) (in the presence of C 2 H 4 ) ejects RH and CO to form Os 3 (CO) 8 (μ 2 -H)−(μ 3 -S)(CHCH 2 ). The structures of the new complexes are described and the probable reaction pathways discussed.

Novel polysulphur bridged metacyclophanes from the iron-catalysed reaction of bis-(2,4-dimethoxyphenyl) sulphide with disulphur dichloride. Evidence for the cleavage of the carbon–sulphur bond by electrophilic agents

The iron-catalysed reaction of bis-(2,4-dimethoxyphenyl) sulphide (3) with disulphur dichloride (S2Cl2) in dilute chloroform solution has been investigated. Surprisingly, the reaction gives 4,6,11,13,18,20-hexamethoxy-1,2,9,16-tetrathia[2.1.1]metacyclophane (4) as the major product, accompanied by minor amounts of 3,5,10,12,17,19,24,26-octamethoxy-1,8,15,22-tetrathia[1.1.1.1]metacyclophane (5), 4,6,11,13,18,20,25,27-octamethoxy-1,2,9,16,23-pentathia[2.1.1.1]metacyclophane (6), and 5,7,14,16-tetramethoxy-1,2,3,10,11,12-hexathia[3.3]metacyclophane (1). The 1H n.m.r. and mass spectra of compounds (4)–(6) are briefly discussed. The unexpected formation of compounds (1) and (4) suggests the occurrence of an unusual cleavage of carbon–sulphur bonds, operated by electrophilic species on sulphur-bridged oligomers, and subsequent rearrangement of the involved intermediates to the cyclic derivatives. This interpretation is supported by the successful chlorinolysis under mild conditions of the sulphide (3) by means of sulphuryl chloride, affording 1,3-dichloro-4,6-dimethoxybenzene (8) and bis-(5-chloro-2,4-dimethoxyphenyl) disulphide (9). A probable reaction pathway is proposed.

Kinetics and mechanism of the anodic dissolution of nickel in HCl-dimethylsulphoxide solutions

The anodic dissolution of nickel in HCl-DMSO solutions containing different supporting electrolytes has been studied between 20–40°C. The electrodissolution and electrodeposition are predominantly activated electrode processes. At high anodic potentials and in the presence of perchlorate ions at high concentration passivation sets in. A probable reaction pathway is postulated which explains most of the experimental findings. Passivation corresponds to a salt precipitation-dissolution process at the electrode vicinity.

The fluorination of 1,3-Bis-(trifluoromethyl)benzene over potassium tetrafluorocobaltate(III)

1,3-Bis-(trifluoromethyl)benzene has been fluorinated over potassium tetrafluorocobaltate under conditions where the bulk of the products are lightly fluorinated. Two aromatic products, 1-fluoro-2,4-bis-(trifluoromethyl)benzene and 1-fluoro-3,5-bis-(trifluoromethyl)benzene, are formed initially, the two associated 1,4-dienes being also found. The mechanistical implications are discussed, along with probable further reaction pathways.

Photochemical ethoxycarbonylmethylation of benzene with ethyl haloacetate in the presence of metallic halides

Photochemical ethoxycarbonylmethylation of benzene with ethyl haloacetate has been studied in the presence of SbCl 5, AlCl 3, ZnCl 2 or FeCl 3. In all cases, ethyl phenylacetate (2·3–24·4%) was obtained as a sole photoproduct and diethyl succinate, which suggests the formation of an ethoxycarbonylmethyl radical, could not be detected. The similar reaction of toluene in the presence of ZnCl 2 gives ethyl p-tolylacetate (12·8%) without o- and m-isomers. A probable reaction pathway involving photochemical electrophilic substitution is discussed.

Photochemical reactions of β,γ-unsaturated aromatic amines

Exposure of a dilute solution of N-allylaniline ( 1) in EtOH to UV light under N 2 gave mainly aniline (57%), accompanied by o-allylaniline (2, 6·8%) and p-allylaniline (3, 11·7%) etc. Irradiation of 1 in the presence of an oxidising agent such as FeCl 3·6H 2O gave different products, quinoline ( 4) in a low yield (2·6%), together with benzene, aniline and an unknown product. No reaction of 1 with FeCl 3·6H 2O to yield 4 occurred in the dark at room temperature. Similarly, N-allyl-α-naphthylamine ( 5) is photo-oxidised with FeCl 3·6H 2O to benzo[ h]quinoline ( 6, 2·4%). Further, irradiation of N-cinnamylaniline ( 8) in the presence of an oxidising agent gave 2-phenylquinoline ( 9, 5%) instead of the expected 4-phenylquinoline ( 10). The 2-phenyl isomer ( 9), but not 10 was obtained in a good yield on photolysis ofN-cinnamylideneaniline ( 11), which is expected in the FeCl 3·6H 2O oxidation of 8. Probable reaction pathways are discussed.

Isotope effect studies on elimination reactions. VI. The mechanism of the bimolecular elimination reaction of 2-arylethylammonium ions

The mechanism of the elimination reaction of 2-arylethyltrimethylammonium ions with ethoxide ion in ethanol has been examined using tracer and kinetic isotope effect techniques. Absence of exchange with solvent of both 2-phenylethyltrimethylammonium-2,2-d2 bromide and 2-(p-trifluoromethylphenyl)-ethyltrimethylammonium-2,2-d2 bromide and the observation of nitrogen isotope effects of 1.3 and 0.9%, respectively, have eliminated a two-step process involving a freely-solvated carbanion intermediate for both salts. The observation of only a slight change in the magnitude of the nitrogen isotope effect when the solvent is changed from ethanol to water has also excluded a zwitterionic intermediate which is specifically hydrogen-bonded to the molecule of ethanol formed by removal of a β-hydrogen by ethoxide ion. Finally, tracer studies using α- and β-dideuterated substrates have eliminated the less probable reaction pathways involving ylide and carbene intermediates. It is concluded that the reaction of 2-arylethyltrimethylammonium salts with ethoxide ion is a concerted E2 process.

The Redox Reaction of 1-Ethoxy-n-heptyl Hydroperoxide

Abstract 1) The reaction of 1-ethoxy-n-heptyl hydroperoxide with ferrous sulfate has given ethyl formate, n-heptanal, ethyl heptanoate and n-dodecane, while the reaction with a mixture of cuprous and cupric chlorides has given ethyl formate, n-hexyl chloride, n-heptanal and ethyl heptanoate. 2) The formation of n-heptanal in both reactions has been attributed to the reduction of the 1-ethoxy-n-heptanoxy radical with ferrous or cuprous ions to the corresponding anion, followed concertedly by the leaving of the ethoxide ion. 3) The probable reaction pathway, especially the difference between the natures of the heterocyclic ether syetem and the linear ether system, has been discussed.