Terpeneless Geranium Oil

#### Geranium Oil, Terpeneless. Although the actual amount of hydrocarbons in geranium oil is comparatively small, the partial or total removal of "light" fractions of geranium oil (during a vacuum distillation) produces quite interesting perfume materials, distinctly different from the parent oil. From a chemical point of view, this treatment is not strictly a deterpenization (compare, e.g. wormwood oil, dethujonized) since the foreruns of a vacuum-distilled geranium oil will contain not only small amounts of pinene and other monoterpenes, but also certain amounts of aliphatic and olefinic alcohols of the C6 to C10-series, perhaps even higher members. Traces of aldehydes, ketones and low-boiling esters are also present in these "head" fractions. The "heart" fraction will consist mainly of the so-called "**Rhodinol ex Geranium**", a mixture of terpene alcohols, laevo-citronellol and geraniol presumably being the main components. In the "tail" fractions, there will again be certain components whose fragrance the perfumers do not appreciate to the same extent as for the rhodinol fractions. Thus, a "**Terpeneless Geranium Oil**" may be a bulking of selected fractions of a vacuum-distilled geranium oil. The fractions are selected esthetically by perfumers who are specifically experienced in this art. Consequently, this product varies significantly according to the origin and the supplier (producer). It is generally assumed that Réunion geranium oil yields the best rhodinol, but apart from the indisputable fact that this oil usually gives the highest yield of terpene alcohol fractions, it is also the most expensive of all the geranium oils. The yield will usually be well over *50%,** *in rare cases as high as 70%, depending upon the content of ketones (laevo-isomenthone and other ketones), etc. in the oil. These will distil immediately prior to the "rhodinol" and they may impart a "minty" note which is harmful to the delicacy of a good rhodinol. The terpeneless geranium oil or "rhodinol ex geranium" (two different perfume materials) are colorless or very pale yellow liquids. The odor of the "rhodinol" is delightfully sweet, yet fresh and rosy, very uniform and tenacious. The odor of the "terpeneless" geranium oil varies according to the individual supplier (producer) of the oil. "**Rhodinol ex Geranium**" is used very extensively in perfumery as a base for rose, muguet, carnation, apple blossom and many other perfume types. Its floral sweetness, delightful freshness and delicate warm-rosy tonalities blend well with the odors of hydroxycitronellal, linalool, geraniol, dimethyl benzyl carbinol, cinnamic alcohol, cyclamen aldehyde, phenyl ethyl alcohol, geranyl esters, linalyl esters, etc. etc. Rhodinol ex geranium is frequently adulterated with "synthetic" rhodinol, laevo-citronellol, dextro-citronellol, geraniol, nerol, fractions of palmarosa oil, citronella oil, phenyl ethyl alcohol, etc. In the evaluation of "rhodinol ex geranium", the instrumental analysis is a most valuable method to produce a proof in cases of suspicion as a result of the olfactory analysis. The fact that the large consumers are still willing to pay over 100 U.S. dollars per kilo for a good "rhodinol ex geranium" should be sufficient proof that there is no competitive substitute for this excellent perfume material.