Camphor Chromic oxide

Camphoric yields eampheite oxide on oxidation with chromic oxide in acetic anhydride at — (Eq. 112), but 1-mcthyl-a-... 

The structure of the bicychc monoterpene borneol is shown in Figure 26 7 Isoborneol a stereoisomer of borneol can be prepared in the labora tory by a two step sequence In the first step borneol is oxidized to camphor by treatment with chromic acid In the second step camphor is reduced with sodium borohydride to a mixture of 85% isoborneol and 15% borneol On the basis of these transformations deduce structural formulas for isoborneol and camphor... 

Most synthetic camphor (43) is produced from camphene (13) made from a-piuene. The conversion to isobomyl acetate followed by saponification produces isobomeol (42) ia good yield. Although chemical oxidations of isobomeol with sulfuric/nitric acid mixtures, chromic acid, and others have been developed, catalytic dehydrogenation methods are more suitable on an iadustrial scale. A copper chromite catalyst is usually used to dehydrogenate isobomeol to camphor (171). Dehydrogenation has also been performed over catalysts such as ziac, iadium, gallium, and thallium (172). 

Bomeol is oxidized to camphor with chromic or nitric acid dehydration with dilute acids yields camphene. Bomeol is readily esterified with acids, but on an industrial scale bornyl esters are prepared by other routes. For example, levorotatory bomeol is synthesized industrially from levorotatory pinenes by Wagner Meerwein rearrangement with dilute acid, followed by hydrolysis of the resulting esters [86]. 

Scheme 34 shows the synthesis of the bc portion (336), which possessed three of the nine asymmetric centers present in cobyric acid. Retrosynthesis determined that (336) could be obtained, via sulfide contraction, from the two intermediates (337) and (338). Ring c was synthesized from (+)-camphor quinone (not shown). Ring b (337) was obtained from 8-methyl-j8-acetylacrylic acid (339), the two adjacent chiral centers being generated in the required relative orientation by a Diels-Alder cycloaddition with butadiene in the presence of tin(IV) chloride. Fractional crystallization served to resolve the diastereomeric a-phenethylamine salts derived from them, eventually affording the compound (340). Oxidation with chromic acid cleaved the double bond in (340) and one of the newly generated... 

A slightly modified procedure - oxidation with 100 per cent excess of chromic acid at 0 °C for a short period - is adopted for strained bicyclic alcohols (e.g. the oxidation of ( —)-borneol to ( —)-camphor, Expt 5.87) and gives excellent yields of the corresponding ketones. Cycle ketones which are susceptible to acid-catalysed epimerisation are moreover obtained by this procedure in a high degree of epimeric purity. 

Dinitropropane. CH3C(N02)2CH3 white crysts with a camphor-like odor mp 53° with subl bp 185.5° d 1.26g/cc subl at RT. V si sol in w and insol in alkalies. Was first prepd in 1876 by the oxidation of propylpseudonitrole, CH3C(N0)(N02)CH3, with chromic acid, or by simply heating it in air at 100° (Ref 2). Nef (Ref 3) prepd it, among other products, by treating Ag dinitroethane with methyl iodide... 

CAMPHOR, NATURAL (76-22-2) Combustible liquid (flash point I55 F/66°C). Violent reaction with strong oxidizers, chromic anhydride, potassium permanganate. Incompatible with chlorates, naphthalene, 2-naphthol, dichlorobenzene. Flow or agitation of substance may generate electrostatic charges due to low conductivity. 

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