Rose oxide, manufacture

Multiple runs of the dark singlet oxygenation for rose oxide manufacture have been carried out successfully in 10 m stirred tank reactors, with easy catalyst recycling via simple extraction steps. 

In 1961, chemists (19) isolated a minor component of geranium oil, characterized it as rose oxide (1), and reported that this compound contributed to the characteristic geranium odor. Rose oxide (1) is manufactured by the photooxidation of citroneUol (8). 

See Section 3 for a discussion of the photochemical synthesis of an endothelin receptor antagonist 199 using the Barton reaction and the synthesis of a precursor to (-)-rose oxide 200 which is of industrial interest to fragrance manufacturers. 

Rose oxide (467), a valuable perfume additive, is manufactured by an ene reaction (Section 6.7.3) of citronellol (468) (derived from lemon grass) with oxygen by irradiation in the presence of Methylene Blue as a triplet photosensitizer (Scheme 6.227).1311 1312... 

Manufacture of rose oxide by ene-type allylic oxidation via dark singlet oxygenation of -citronellol... 

M.p. 190-192 C. The enolic form of 3-oxo-L-gulofuranolactone. It can be prepared by synthesis from glucose, or extracted from plant sources such as rose hips, blackcurrants or citrus fruits. Easily oxidized. It is essential for the formation of collagen and intercellular material, bone and teeth, and for the healing of wounds. It is used in the treatment of scurvy. Man is one of the few mammals unable to manufacture ascorbic acid in his liver. Used as a photographic developing agent in alkaline solution. 

This route might be an environmentally benign alternative to the conventional method for the production of the very important fragrance phenylethanol which has the smell of roses. This compound is still manufactured out of ethylene oxide and benzene in the presence of a high excess of AICI3, yielding unwanted toxic by-products. 

The consumption of phenol rose noticeably after the 1920 s with the increase in its importance as a raw material for phenolic resins, for the manufacture of 8-capro-lactam and the production of bisphenol A. The oxidative conversion of cumene into phenol and acetone has proved to be an environmentally safe and economical process thus it gained an edge over the other processes and is presently the only phenol process operated on a worldwide scale. 

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