Sublimation camphene

Camphene [565-00-4] M 136.2, m 51-52°, b 40-70 /10mm. Crystd twice from EtOH, then repeatedly melted and frozen at 30mm pressure. [Williams and Smyth J Am Chem 5oc 84 1808 1962.] Alternatively it is dissolved in Et20, dried over CaCl2 and Na, evaporated and the residue sublimed in a vacuum [NMR Chem Ber 111 2527 1978]. 

The isobomeol so formed melts at 212°, but the determination must be carried out in a sealed tube, as the melting-point is very dose to the temperature of sublimation. It is, however, very rarely that the isobomeol so prepared is free from impurities, and the melting-point will often be found to be as low as 203° to 205°. It is therefore necessary to pare derivatives of the isobomeol in order to identify it with certainty. Kie compound with bromal melts at 71° to 72°. Other compounds will be found mentioned under isobomeol . By dehydration by means of zinc chloride, isobomeol is easily converted into camphene, melting at about 49° to 50°. 

In recent years, some monoterpenes have attracted some interest as environment-friendly solvents for polymeric systems. Camphene, which is both harmless and readily sublimed, has been tested as solvent for polypropylene... 

Camphene is a minor component of many terpene oils from which it is purified. It is a waxy solid, which sublimes at room temperature. Because it contains a reactive double bond, it tends to oxidize to form non-volatile oxidation products. For this reason, the commercial product is normally compounded with an antioxidant. 

The solid, subliming materials - camphene, tricyclene, menthol and cyclododecane - have been used as temporary, volatile consolidants and release agents (lagers lagers, 1999 Cleere, 2005). These have been chosen to be suitable because of their ease of use and resistance to polar solvents. Of these, cyclododecane is the preferred material because it is the most stable to degradation, has fewer impurities, and has fewer health and safety risks. It is important that the material applied contains as little as possible non-volatile material, which will remain after treatment as a contaminant. 

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