Olefins chromic acid oxidation

A Cr(VI)-catalyst complex has been proposed as the reactive oxidizing species in the oxidation of frans-stibene with chromic acid, catalysed separately by 1,10-phenanthroline (PHEN), oxalic acid, and picolinic acid (PA). The oxidation process is believed to involve a nucleophilic attack of the olefinic bond on the Cr(VI)-catalyst complex to generate a ternary complex.31 PA- and PHEN-catalysed chromic acid oxidation of primary alcohols also is proposed to proceed through a similar ternary complex. Methanol- reacted nearly six times slower than methanol, supporting a hydride transfer mechanism in this oxidation.32 Kinetics of chromic acid oxidation of dimethyl and diethyl malonates, in the presence and absence of oxalic acid, have been obtained and the activation parameters have been calculated.33 Reactivity in the chromic acid oxidation of three alicyclic ketoximes has been rationalized on the basis of I-strain. Kinetic and activation parameters have been determined and a mechanism... 

Chromic acid oxidation of olefins can rarely be used for the preparation of oxiranes because they occur as intermediates that rapidly undergo further transformation. From an investigation of the mechanism of oxidation of triaryl-substituted olefins, it was concluded that a carbonium ion or cyclic chromate ester is a possible intermediate. Selective epoxidation of compounds containing conjugated double bonds is attainable by means of chromic-acid oxidation (Eq. 48) 535 Exclusively cis product was obtained from a highly substituted octalin with Na2Cr04, KMn04, or ozone (Eq. 49). ... 

Sondheimer et al. used the catalytic method vrith success in another oxidative fission of a Barbier-Wieland diphenylethylene with which ozonolysis and chromic acid oxidation proceeded poorly. Sarel and Yanuka found the method successful as applied to the diphenylethylene (2) with which the periodate-osmium tetroxide method was completely ineffective. The olefinic compound (2) was dissolved in... 

Brown, H. C., Garg, C. P. 1961. Chromic acid oxidation of organoboranes. A convenient procedure for converting olefins into ketones via hydroboration. J. Am. Chem. Soc. 83 2951-2952. 

Oxidation of Straight-Chain 1-Olefins. Oxidation of a-olefins has been thoroughly studied using ozone, peracids, nitric acid, chromic acid, and others. 

When heated in the presence of a carboxyHc acid, cinnamyl alcohol is converted to the corresponding ester. Oxidation to cinnamaldehyde is readily accompHshed under Oppenauer conditions with furfural as a hydrogen acceptor in the presence of aluminum isopropoxide (44). Cinnamic acid is produced directly with strong oxidants such as chromic acid and nickel peroxide. The use of t-butyl hydroperoxide with vanadium pentoxide catalysis offers a selective method for epoxidation of the olefinic double bond of cinnamyl alcohol (45). 

While polymeric surfaces with relatively high surface energies (e.g. polyimides, ABS, polycarbonate, polyamides) can be adhered to readily without surface treatment, low surface energy polymers such as olefins, silicones, and fluoropolymers require surface treatments to increase the surface energy. Various oxidation techniques (such as flame, corona, plasma treatment, or chromic acid etching) allow strong bonds to be obtained to such polymers. 

When hydroboration of an olefin is carried out with the intention of oxidizing an initially formed secondary alcohol to a ketone, hydrogen peroxide oxidation can be dispensed with and the alkylborane oxidized directly with chromic acid. Thus Pappo converted a hydroxyl-free A -steroid into a mixture of stereoisomeric alkyl-boranes comparable to (1) and (2), oxidized the mixture with chromic acid, and obtained the 6-keto-5a-steroid in good yield the initially formed 6-keto-5i3-steroid underwent isomerism in the process. H. C. Brown developed an efficient two-phase system for oxidation of either alkylboranes or free alcohols to the ketones using aqueous chromic acid and ether. 

Barbier-Wieland degradation. Stepwise carboxylic acid degradation of aliphatic acids (particularly in sterol side chains) to the next lower homo log. The ester is converted to a tertiary alcohol that is dehydrated with acetic anhydride, and the olefin oxidized with chromic acid to a lower homologous carboxylic acid. 

More powerful oxidants are almost always needed. Those commonly used for cleavage of olefins — and for other degradations — include nitric acid, hydrogen peroxide, permanganate, chromic acid, very concentrated alkali hydroxides, and in particular ozone. The products to be expected from oxidative fission of an ethylenic carbon-carbon double bond are carbonyl compounds — an aldehyde or a ketone or both according as the doubly bonded carbon atoms do or do not carry a hydrogen atom — but it often happens that 1,2-glycols are obtained as intermediates. 

Aldehydes can also sometimes be obtained from olefins by oxidation with chromic acid or nitric acid, e.g., acetylvanillin from isoeugenol.111... 

The good solvent resistance of polyethylene and other olefins precludes the use of solvent-type cements. Several commercial rubber-type adhesives produce moderate adhesion with polyethylene that has been surface treated. One technique for surface treatment is to dip polyethylene in a chromic acid bath (made up of concentrated sulfuric acid 150 parts by weight, water 12 parts, and potassium dichromate 7.5 parts) for about 30 sec at 70°C. The parts are rinsed with water after this treatment. Still another effective surface treatment for producing cementable surfaces on polyethylene is electrical discharge. The open oxidizing flame method is also used extensively for this purpose. 

Though the terminal oxidation of a vinylidene group in an hindered olefin to a carboxyl function by chromic acid had prior analogy (73, 81), the formation of v /-longifolic acid (128) and the ring-expanded dione... 

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