Alcohols oxidation with chromic acid

Cyclopropene underwent cycloaddition to tropylium perchlorate in aqueous dioxane at 20 °C to give an oily alcohol oxidation with chromic acid gave predominantly the ketone 4 derived from endo addition. ... 

An optically active, secondary terpene alcohol. ( —)-Piperilol is found in various eucalyptus oils and (-l-) piperitol in the oil from a species of Andropogon. A somewhat viscous oil of pleasant smell. It yields piperitone on oxidation with chromic acid. 

It is of interest that the methyl alcohol 81 underwent oxidation with chromic acid to afford 3-acetylfervenulin 83 in good yield, whereas the same conditions resulted in the conversion of alcohol 79 into fervenulin 8. The desired product of this latter transformation, that is, fervenulin-3-carboxaldehyde 82, could, however, be obtained, albeit in low yield, by the oxidation of alcohol 79 with manganese dioxide. Fervenulin-3-carboxaldehyde 82 could be obtained in much better yield from the treatment of 3-styrylfervenulin 68 with periodate in the presence of osmium tetroxide, or by ozonolysis of the same substrate. 

Pyrrolizidine alcohols are readily oxidized. Stereoisomeric 1-hydroxymethylpyrrolizidines when oxidized with chromic acid afford stereoisomeric pyrrolizidine-1-carboxylic acids (see Section III, C).81,90 Secondary alcohols, when subjected to Oppenauer oxidation or chromic acid treatment, yield amino-ketones (cf. refs. 72, 77, and 81). 

Benzyl alcohol readily undergoes the reactions characteristic of a primary alcohol, such as esterification and etherification, as well as halide formation. In addition, it undergoes ring substitution. In the presence of acid, polymerization is observed, and the alcohol can be thermally dehydrated to toluene [108-88-3], Catalytic oxidation over copper oxide yields benzaldehyde benzoic acid is obtained by oxidation with chromic acid or potassium permanganate. Catalytic hydrogenation of the ring gives cyclohexylmethanol [100-49-2]. 

Other chromium-based reagents are also found to oxidize alcohols, following a mechanism like the one depicted above for oxidation with chromic acid.4... 

The chemical properties and uses of propargyl alcohol has three potentially reactive sites (1) a primary hydroxyl group (i.e., CH2OH), (2) a triple bond (-C=C-), and (3) an acetylenic hydrogen (-C=CH) that makes the alcohol an extremely versatile chemical intermediate. The hydroxyl group can be esterified with acid chlorides, anhydrides, or carboxylic acids, and it reacts with aldehydes or vinyl ethers in the presence of an acid catalyst to form acetals. At low temperatures, oxidation with chromic acid gives propynal or propynoic acid ... 

Medium effects on oxidations with HxCrOa. The oxidation of an alcohol such as t-butylphenylmethanol (1) with chromic acid in aqueous acetic acid results in significant amounts of the cleavage products benzaldehyde and f-butyl alcohol. This cleavage is reduced to 6% when the reaction is conducted in aqueous acetone it is completely suppressed on addition of oxalic acid (6 equiv.), which is known to accelerate oxidations with chromic acid (5, 538). 

Selective oxidation of a primary alcohol. The final step in a recent synthesis of strophanthidin required selective oxidation of the primary hydroxyl group of stro-phanthidol (1) to an aldehyde group. Oxidations with chromic acid, N-haloamides,... 

Norbornanone is generally prepared from the Diels-Alder adduct of cyclopentadiene and vinyl acetate by hydrogenation, saponification, and oxidation with chromic acid in acetic acid solution. The present procedure, which gives higher over-all yields in fewer steps, makes use of the superior solvent, acetone, for mild chromic acid oxidations and of the observation that formate esters of secondary alcohols can be oxidized directly to ketones. ... 

Acetaldehyde or ethanal is the second member of the series and corresponds to ethyl alcohol from which it is made by oxidizing with chromic acid (potassium bichromate and sulphuric acid). 

Samandarone (XVI) is the main alkaloid of S. maculosa maculosa in 8. maculosa taeniata it is one of the minor alkaloids. It can readily be obtained from samandarine by oxidation with chromic acid conversely, samandarone is reduced stereospecifically to samandarine by sodium and alcohol or by sodium borohydride. 

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. 

The diosphenol (214) has been prepared from 3a-bisnorcholanic acid (217), itself obtained from ergosterol. The amino-group is introduced with retention of configuration by means of the Curtius reaction and methylated to give 3a-acetoxy-20a-dimethylamino-5/5-pregnane (216). After hydrolysis and oxidation with chromic acid, the ketone (215) is obtained. Aerial oxidation of (215) in the presence of potassium t-butoxide in t-butyl alcohol gives (214). 

Fine, glistening plates from ether, mp 212.8-216,8 gives no depression of melting point when mixed with cortisone. Very sparingly sol in water, ether. Sol in acetone, methanol, alcohol. Gives a carmine-red fluorescence reaction with coned. H2SOt. Reduces ammoniacal silver nitrate soln at room temp, uv max 242 nm (E 500). Oxidation with chromic acid in glacial acetic acid yields 4-androstene-3.17-dione. 

Norlobelanidine, C21H27O2N. Lobelanidine is separated from the other Lobelia alkaloids by crystallization of its sparingly soluble hydrochloride (488), and the alcoholic mother liquors contain the hydrochloride of a secondary base. This base, which is optically inactive, melts at 120° and forms a hydrochloride, m.p. 244°, a nitrate, m.p. 179-180°, and a hydriodide, m.p. 211°. Since it is converted by methyl p-toluenesulfonate to lobelanidine and by oxidation with chromic acid to norlobelanine, the base is norlobelanidine. It is obtained as an intermediate product in the synthesis of lobelanidine (486). 

Pinene forms with one molecule of dry hydrogen chloride, an addition-product, which is called artificial camphor (m.p. 125°) on account of the fact that it resembles camphor in appearance and odor. When this compound is heated with alcoholic potash or with a mixture of anhydrous sodium acetate and glacial acetic acid, hydrogen chloride is eliminated and camphene, an isomer of pinene, is formed. Camphene, the structure of which is not known, melts at 50° it is converted into camphor CioHieO (649) when oxidized with chromic acid. d-Camphene is found in ginger Z-camphene, in turpentine and in citronella and other essential oils. 

Mechanism 15.3 outlines the mechanism of chromic acid oxidation of 2-propanol to acetone. The alcohol reacts with chromic acid in the first step to give a chromate ester. A carbon-oxygen double bond is formed in the second step when loss of a proton from carbon accompanies cleavage of the bond between oxygen and chromium. The second step is rate-determining as evidenced by the fact that (CH3)2CHOH reacts 6.7 times faster than (CH3)2CDOH. If the second step were faster than the first, no deuterium isotope effect (Section 5.17) would have been observed. 

PCC is selective for the oxidation of primary alcohols to aldehydes. It is less reactive than the previously discussed oxidation with chromic acid in aqueous sulfuric acid, and the reaction is run stoichiometrically so that no PCC remains once all the alcohol molecules have been converted to aldehyde. PCC also has little effect on carbon-carbon double bonds or other easily oxidized functional groups. In the following example, geraniol is oxidized to geranial without affecting either carbon-carbon double bond ... 

When a primary alcohol is oxidized with chromic acid, a carboxyhc acid is obtained. It is generally difficult to control the reaction to produce the aldehyde. 

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