Perfumery:
Basic Facts for Pharmacists' CURT P. WIMMER
Columbia University College of Pharmacy, New York City
I D you ever realize that the delightful new-mown hay, trefle, or orchid perfume used as welcome g ~ f t smay not contain a drop of natural flower or vegetable oil? Yet, this may be exactly the case. Perfumery, as practiced today, must be considered a science as well as an art. Its scientific aspect has progressed tremendously within the past generation. Improvements in the extraction and rectification of aromatic plant constituents have furnished the compounding perfumer with materials having great odor and strength value. The organic chemist has learned to synthesize substances which may or may not have been found as component parts of natural volatile oils -some of which have found wide use and important applications. The modern perfume industry is founded upon the results of research carried on during the 19th century. The French scientist, Dumas, was the first critically to examine a flower oil, to determine its composition. He found it to be a mixture of organic substances and identified several of them. Later on (about 1872 to 1890), French and German chemists determined the exact nature of these substances and succeeded in preparing them not only by extraction from the plant but by direct synthesis from coal tar. Since then, the number of natural and artificial perfume materials has increased to such an extent that even a professional perfumer is not acquainted with all of them. Although perfume substances of animal origin are few in number, they are very important; among them are musk, civet, and ambergris. They are almost indispensable in fine perfumery; and are used in perfume mixtures as tinctures or infusions, imparting not only exciting and stimulating odor notes, but simultaneously serving as fixatives-helping to equalize the rapidity of evaporation of the several components of the mixture and thus prolonging the lasting qualities of the perfume. Musk is obtained from the preputial follicles of the male musk deer, a small, shy, and very fleet animal that comes out of its hiding place a t night to seek food and water; it always travels in pairs. The mnsk deer is indigenous to the mountains of northern India, China, and Siberia. It is hunted or caught in traps; usually both male and female deer are slaughtered indisaiminately in the search for the precious musk. As a consequence, natural musk is becoming scarcer and more expensive. It soon will be unobtainable. Artificial musks are available, but there really is no good substitute. Ambergris is a pathological excretion from the
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Reprinted, in part, from The .Wwck Report, 54,24 (February, 1945)
intestine of a certain species of whale. It is, a t times, found floating on the ocean and cast upon the seashore; but most of it is obtained by whalers and brought back in whaling boats. It comes in black or opaque, gray lumps of varying sizes and weights, and commands a high price because of the inimitable fine odor note it imparts to perfumes. Civet comes from an Abyssinian cat whose abdominal pouches fill with the perfume material when the cat is angered. It is a dark-brown, soft paste, which has a disagreeable odor when in concentrated form; however, when highly diluted, a distiuctive, stimulating perfume note is obtained. PROCESSING AROMATICS FROM PLANTS
Next in importance as perfume components are the numerous essential or volatile oils. Their method of preparation, for the perfume industry, depends upon several factors, such as the nature and habitat of the plant, the part used, and the desired form of the aromatic constituents. In general, the methods used may be classified as expression, distillation, maceration, and extraction by means of a suitable solvent. Expression is used for the preparation of citrns oils, such as lemon, orange, or bergamot oil. The oil is found in the tiny plant cells, located directly underneath the epidermis; simple pressure of the peel will liberate the oil. The method of expression varies from a simple twist by means of skilled fingers, to machinery which not only mashes the entire fruit but separates the oil from the other extraneous matter. Most of the essential oils are obtained by some form of distillation. The apparatus employed varies considerably, from the simple still of the ambulant farmer who sets up his apparatus right in the field where the plants grow, using a little stream nearby to supply the cooling water for the condenser, to the huge still in the modem factory where engineers and chemists carefully control the process. Maceration is employed for flowers whose constituents are not injured by heat used in the process. The flowers are immersed in wann liquefied fat and left there for va~yingperiods of time--sometimes eight hours or more. The mixture then is strained and the aromatized fat is allowed to cool and solidify. The aromatics thus removed are now in the form of a "pomade." If, however, the perfume in the flower is apt to be affected by heat, the process, termed enfEeurage, is employed. For example, tuberose, jasmiu, and jonquil odors are so sensitive to warmth that cold extraction must be employed. In enfiewage, a glass frame about 30 inches in length is covered with a thin layer of fat, usually a suet-lard
mixture; upon this a thin layer of flowers is spread. A number of such frames are prepared and stacked high, one upon the other; they are allowed to stand for days to enable the fat to absorb the aroma. The extracted flowersthen are removed and fresh ones added in their place. The manufacturing perfumer knows from experience how many changes are necessary to saturate the fat with the flower perfume. The fat is next removed from the frames and extracted with pure alcohol; the perfume dissolves in the alcohol which, in turn, is evaporated a t a very low temperature or under a vacuum. The residue is the concentrated perfume material known as a "concrete soluble." The most efficient method of extracting aromatic coustituents from plant parts consists of using petroleum benzine of low snecific 'mavitv. The freshlv cut flowers , are placed into batteries of percolators, in which the solvent circulates freely and extracts the aromatics from the flowers. The benzine solution is evaporated either spontaneously or under a vacuum, leaving the aromatics as a >nastv residue. This contains waxes , and other plant constituents which are subsequently removed by dissolving the residue in strong alcohol and cooling the solution to about 5T.,when the waxes separate out and the liquid is filtered while still cold. Upon evaporation of the alcohol, the aromatics remain in their purest and most concentrated form, known as "absolute." It usually is very expensive, prices ranging from $250 to $1000, or even more, are not unusual for a pound of absolute. In reviewing perfume materials, one must include moss extracts, resins, e. g., labdanum, benzoin, myrrh, tolu, storax, and many others which serve important purposes in perfume mixtures. Pure organic substances used are the isolates and synthetics; the former are plant constituents separated from an essential oil in more or less pure form and used in the compounding of perfumes; geraniol, citronellol, linalol, and borne01 are g o d examples of isolates.
minute quantities, but each one is essential to the production of the correct odor note. Our sense of smell is so keen that we would quickly notice the absence of any of them. IMPORTANT FACTORS I N BLENDING
A perfume consists of three factors: the main or basic odor substance, the adjuvant (a negative or positive potentiator), and the fixative. Each of the three factors may be very simple or complex. A good example is that of violet perfume oil. Is the basic odor substance to be used an oil of violets? No, that would be too expensive; it would make the perfume prohibitive in cost. The composition is based on a substance known as ionoue, which is prepared from oil of lemongrass and acetone; when highly concentrated i t has a grass-hay odor, but an attractive, violet odor when highly diluted with alcohol. This is the basic substance which must be supported by adjuvants, usually substances of similar odor notes, such as orris oil or concrete sweetened with heliotropin and vanillin. Next, one must use certain essential oils to round out the chemical effect, such as oil of ylangylang, oil of sandalwood, and others. If a "leafy" note to our violet odor is desired, a small amount of methyl heptine carbonate may be added, or if unmindful of cost some real violet-leaf concrete may be used instead. To improve the odor still further, small amounts of absolutes may be included. Since the perfume is to last on the ladies' handkerchiefs for some time, we must look for a proper fixative; it is in the choice of this ingredient that the artistic intuition of themaster perfumer reveals itself. From the numberless substances a t hand, he must select the right combination-one that blends exactly and gives the full, fragrant violet aroma upon aging. Just as ionone is the basic substance for violet odors, so are other basic materials for each odor type available to the perfumer; viz., hydroxycitronellal for the lily, lily-of-the-valley, and lilac; iso-eugeuol and eugenol for carnations; ~eraniol,citronellol, and -phenyl-ethyl alcohol for the SYNTHETICS iose types. The number of organic synthetics prepared by the Perfumers distinguish among several types of odor chemist is increasing by leaps and bounds. Among combinations: the sinele flower odor. the sinele them are chemicals that originally were discovered in flower bouquet, and th'fantasy odor. The first one essential oils, but now are made from coal-tar deriva- presents the beautiful odor of one single flower, such tives; for example, methyl anthranilate was found in oil as the tea rose, lavender, or lilac. This type is the of neroli (orange flower oil); it now is prepared syn- most difficult to compose. The single flower bouquet thetically. Perfume materials also are synthesized gives the effect of a bouquet of flowers with one of the without regard to their existence in plants; but a flower odors predominating, while the bouquet odor is chemist with a good sense of smell has found i t useful that of a beautiful bouquet in which none of the comfor perfume mixtures, e. g., diphenyl oxide. It was ponents is permitted to overshadow the odor of the prepared many years ago and stood on the shelves of the others. Then there is the fantasy odor perfume in chemical museum. No one recognized its value until which widest latitude is given to the creative perfumer an alert perfume chemist discovered its properties. who endeavors to produce odors and fragrances not Now, it is invaluable in the preparation of geranium found in nature, but which, nevertheless, are engaging, odors. From the preceding outline, it is obvious that a exciting, and captivating for the moods of temperaperfume is a very complex mixture; some perfumes mental femininity--odor combinations that blend with have more than a hundred constituents, many in and enhance the charm of every personality. ~
