Wild volatile-oil plants and their economic importance

Part 2

Chapter 23,582 wordsPublic domain

Borneol, although closely allied to camphor, is much less used commercially in the United States, principally because of the difficulties encountered in its collection by the natives in Borneo and the Malay Archipelago. It would probably be used more extensively in this country if a sufficient supply could be obtained at reasonable prices, the high price of the article preventing its use for technical purposes.

Borneol is antiseptic and stimulant, and finds its main use in medicine, but is also in demand in the perfume industry, the esters being especially desirable. The acetic acid ester of borneol (bornyl acetate) is in fact the odoriferous principle of pine-needle odor. Borneol is used mainly as a base for the manufacture of bornyl acetate which is much used in the preparation of pine-needle odors by perfumers. It is in considerable demand in the Orient where, according to Janse,[24] it is sought by the Chinese, who use it principally in religious ceremonies, but also in medicine and the perfuming of India inks. The Chinese are said to pay as much as $1.25 an ounce for it, and since the native producers are unable to supply the demand, a synthetic borneol, which is not a pure substance but a mixture of borneol and isoborneol, has entered the markets of the East.

Cineol, or eucalyptol, is a very important and valuable article of commerce. Its virtue as a remedial agent has placed it in a high position among the important drugs used in the treatment of human ailments. The uses of cineol are entirely medicinal. It is used both internally and externally, and also as an inhalant. It is administered internally in the form of various pharmaceutical preparations for the treatment of colds, pneumonia, bronchitis, and other respiratory affections. As an inhalant it is used for asthma, diphtheria, and throat troubles in general. Together with other medicaments cineol is applied externally in the form of ointments or liniments. Furthermore, it has a wide application in the manufacture of dentifrices, mouth washes, and other preparations where an antiseptic action is desired. At the present time pure cineol, as prepared from eucalyptus oil, commands a price of $1 to $2 a pound.

PURPOSE OF THE INVESTIGATION OF WILD AROMATIC PLANTS NATIVE TO THE UNITED STATES.

Since many valuable volatile oils and volatile-oil constituents have been discovered in plants growing wild in various parts of the world, it has been thought that an investigation of the wild aromatic plants of this country would reveal many, now practically useless and possibly classed as weeds, which might become of commercial value.

The economic value of these plants is determined not only by the proportion of oil which they contain, but by the constituents of the oil; hence careful analyses must be made in order to discover what these constituents may be. The present bulletin deals with the analyses of three heretofore unutilized plants, which may be grouped together, because the oils obtained from them are all of a camphoraceous character and because they contain several constituents in common. These, gathered from different sections of the United States from entirely different habitats and belonging to unrelated families, are as follows: Black sage (_Ramona stachyoides_) from California, wild sage (_Artemisia frigida_) from South Dakota, and swamp bay (_Persea pubescens_) from Florida.

SPECIAL INVESTIGATIONS.

BLACK SAGE.

BOTANICAL DESCRIPTION AND DISTRIBUTION.

_Ramona stachyoides_ (Benth.) Briquet (synonyms--_Audibertia stachyoides_ Benth., _Salvia mellifera_ Greene), commonly known as black sage (figs. 1 and 2), is a shrubby aromatic perennial, occurring from middle to southern California on low hills from April to June. The shrub attains a height of 3 to 6 feet and possesses herbaceous leafy branches with oblong leaves, green and wrinkled above and ash colored and hairy below. The flowers are white or lilac and in whorls or heads. The leaves have a strongly aromatic and decidedly camphoraceous odor, the woody branches being very brittle and also strongly aromatic.

DISTILLATION OF THE OIL.

A quantity of the fresh herb partly in bloom, including the flowering tops, branches, and leaves, was distilled by steam in the vicinity of Los Angeles, Cal., in April, 1908, and yielded 0.75 per cent of oil. The oil was nearly colorless and possessed a penetrating, camphoraceous, yet agreeable odor, with a bitter, camphorlike taste. At 24° C. the specific gravity was found to be 0.9144; specific rotation A_{D} = +30.2°; re-fraction at 24° C., 1.4682. The oil was soluble with clear solution in 1½ volumes of 70 per cent alcohol, becoming turbid with 3½ volumes or over.

SEPARATION OF STEAROPTENE.

Owing to the very strong camphoraceous odor of the oil, a separation of the stearoptene suggested itself. In order to separate a solid body which is held in solution by a volatile oil, the “freezing-out” method is usually employed. Accordingly 100 grams of the oil were subjected to a freezing mixture of ice and salt. A temperature of -15° C. was attained, and flaky crystals formed throughout the oil. The crystals were separated by being thrown on a force filter and the remaining oil again subjected to the cold, when a second lot was obtained, which was likewise separated. A total of 11.3 grams of crystals was separated, corresponding to a yield of 11.3 per cent. These crystals were soft and flaky in nature and possessed the characteristic odor of camphor.

IDENTIFICATION OF CAMPHOR.

In order to identify the crystalline substance obtained from the oil, a small quantity was sublimed, and the usual tests of melting point, boiling point, and rotation were applied. For further recognition of the compound, an attempt was made to prepare an oxime. Accordingly the method of Auwers[25] was applied, which, briefly, is as follows: To a solution of 10 parts of camphor in 10 to 20 times the amount of 90 per cent alcohol is added a solution of 7 to 10 parts of hydroxylamine hydrochlorid and 12 to 17 parts of a soda solution. If turbidity results, more alcohol is added and the mixture is heated on a water bath until a small portion of the solution remains clear upon the addition of water or until the resulting turbidity disappears, when a few drops of soda solution are added and no free camphor remains. The mixture is then diluted with water, filtered if necessary, and neutralized with dilute hydrochloric acid. The camphor oxime which separates is recrystallized from alcohol or ligroin. It melts at 118° to 119° C.

The above method applied to the sublimed crystals resulted in the formation of an oxime which melted at 120° to 124° C. Since an oxime was obtained (indicating possible ketonic characters), application was made of another reaction for ketones, namely, the formation of semicarbazone. Tiemann’s method[26] for the preparation of camphor semicarbazone was applied. The method is as follows: 1.5 grams of camphor dissolved in 2 cubic centimeters glacial acetic acid are treated with a solution of 1.2 grams of semicarbazid hydrochlorid and 1.5 grams of sodium acetate in 2 cubic centimeters of water. Water is added and the crystalline compound recrystallized from alcohol. The melting point of camphor semicarbazone is 236° to 238° C.

The sublimed crystals when treated in the above manner yielded a semicarbazone which melted at 232° C.

For a comparison of this substance with pure camphor, a tabulation was made of the more common physical properties and chemical tests.

+Table I.+--_Comparison of properties of crystals from oil of black sage and of pure camphor._

The table shows very close similarities in the melting point, boiling point, and rotation of the crystals from the oil of black sage and of pure camphor. The melting points of the oximes and semicarbazones, though not corresponding so well, seemed to indicate that the crystals were in all probability camphor. To further confirm the assumption that the compound from the oil was camphor, an elementary analysis of the compound was made after being twice sublimed.

0.1273 gram of crystals gave 0.1199 gram H_{2}O, corresponding to 10.5 per cent hydrogen.

0.1273 gram of crystals gave 0.3228 gram CO_{2}, corresponding to 79.7 per cent carbon.

C_{10}H_{16}O/camphor requires { 79 per cent carbon. { 10.5 per cent hydrogen.

0.1279 gram of crystals gave 0.1244 gram H_{2}O, corresponding to 10.8 per cent hydrogen.

0.1279 gram of crystals gave 0.3761 gram CO_{2}, corresponding to 79.9 per cent carbon dioxid.

The combustion results seemed to indicate that the compound is identical with that of camphor, as the above tabulation also clearly shows.

CHEMICAL EXAMINATION OF THE OIL.

CHEMICAL CONSTANTS.

Preliminary to the detailed chemical examination of the oil the usual chemical constants were determined.

By neutralization of a weighed quantity of the oil with standard potassium hydroxid V. S., the acid number (the number of milligrams of potassium hydrate required to neutralize 1 gram of oil) was found to be 2.

The ester number (the number of milligrams of potassium hydroxid required to saponify the esters in the oil) was found to be 2.5, which, calculated as bornyl acetate, corresponds to 0.88 per cent.

The ester number after acetylization of the saponified oil with acetic anhydrid (and which represents the total amount of alcohols present) was 27.1, which, calculated as borneol, represents a total of 7.58 per cent of borneol in the oil, both free and in combination.

FREE ACIDS.

The original oil was slightly acid, as indicated by the acid number previously mentioned. The free acid was shaken out from a quantity of the oil with a 10 per cent solution of sodium carbonate. The shaking was repeated several times and the alkaline liquids united. The united alkaline liquids were shaken out with ether in order to remove any oil held in suspension. The sodium-carbonate solution was then evaporated to a small bulk on a water bath, acidified with sulphuric acid, and distilled with steam. No oily globules separated, showing absence of higher insoluble acids. The distillate, which was decidedly acid, was neutralized with sodium-carbonate solution and evaporated to a small volume. The liquid which now represented the sodium salts of the free acids present in the oil was precipitated fractionally with a dilute silver-nitrate solution. Four fractions resulted. Each fraction was dried to constant weight and burned.

Fraction 1. 0.1014 gram silver salt = 0.0785 gram silver = 76.3 per cent silver.

Fraction 2. 0.1000 gram silver salt = 0.077 gram silver = 77 per cent silver.

Fraction 3. 0.1116 gram silver salt = 0.0859 gram silver = 76.9 per cent silver.

Fraction 4. 0.1088 gram silver salt = 0.077 gram silver = 70.8 per cent silver.

Fraction 4 indicates the presence of formic acid, the silver salt of which requires, theoretically, 70.5 per cent of silver. Fractions 1, 2, and 3 indicate silver carbonate (which requires, theoretically, 78 per cent of silver) with a slight admixture of silver formate. The presence of silver carbonate was caused by a possible slight excess of sodium carbonate being added when the acid distillate was neutralized.

COMBINED ACIDS.

_Saponification._--For the purpose of determining the acids held in combination in the oil in the form of esters, the oil was saponified with alcoholic potassium hydrate by heating on a water bath with a reflux condenser for one-half hour. Water was added to the mixture, and the oil separated in a layer. After removing the excess alcohol on a water bath, the alkaline solution was shaken out with ether to remove any adhering oil. The remaining solution was evaporated to a small volume, acidified with sulphuric acid, and distilled with steam.

The distillate from the above was extracted with ether and the ether evaporated spontaneously. Only a trace of an acid residue remained, which was neutralized with a solution of potassium hydroxid and precipitated in three fractions:

Fraction 1. 0.1012 gram silver salt = 0.0893 gram silver = 88 per cent silver.

Fraction 2. 0.0774 gram silver salt = 0.0637 gram silver = 82.3 per cent silver.

Fraction 3. 0.0758 gram silver salt = 0.0502 gram silver = 66.2 per cent silver.

The first two precipitates, when dried, consisted principally of silver oxid, which, theoretically, contains 89.2 per cent of silver. A slight excess of potassium hydroxid during neutralization was doubtless responsible. Fraction 3 would seem to point to the presence of acetic acid in the oil, silver acetate requiring 64.6 per cent of silver.

The aqueous acid portion remaining after the ether extraction was neutralized with sodium carbonate concentrated to small bulk and precipitated with silver nitrate in three fractions. Fraction 1 contained 76.2 per cent of silver; fraction 2, 77 per cent; and fraction 3, 74 per cent. Since silver formate contains 70.5 per cent of silver, a trace of formic acid is possibly present in the oil in combination.

The esters of the oil, as shown by the above results, are present in the oil principally as acetates, with a possible trace of formates.

FRACTIONATION OF THE OIL.

In order to ascertain the total percentage of camphor and to separate the remaining constituents as completely as possible, a quantity of the oil was fractionated into seven fractions, as follows:

Fraction 1, 160° C.; fraction 2, 160° to 170° C.; fraction 3, 170° to 178° C.; fraction 4, 178° to 182° C.; fraction 5, 182° to 186° C.; fraction 6, 186° to 190° C.; fraction 7, 190° to 195° C. These fractions (125 grams) were refractionated into 10 separate fractions, as shown in Table II, a determination of the physical properties of each fraction also being made.

+Table II.+--_Fractionation of the oil of black sage, showing the physical properties of the fractions._

+------------+---------+--------+----------+-----------+------------- | |Distilled|Specific| Rotation |Re-fraction| Fraction.|Temperature.| over. | gravity|in 50 mm. | N_{D} | Remarks. | | | at | tube. | 28° C. | | | | 26° C. | | | ---------+------------+---------+--------+----------+-----------+------------- |_Degrees C._| _Per | |_Degrees._| | | | cent._ | | | | 1 |Below 160 | 2.5 | 0.8070 | + 6.9 | 1.4570 | Slight | | | | | |terebinthine | | | | | |odor. 2 |160 to 170 | 6.8 | .8768 | +10.1 | 1.4613 | Cineol-like | | | | | |odor. 3 |170 to 174 | 7.8 | .8865 | +10.1 | 1.4640 | Do. 4 |174 to 178 | 12.1 | .8920 | +10 | 1.4648 | Decidedly | | | | | |cineol-like | | | | | |odor. 5 |178 to 182 | 14.8 | .8996 | +10.2 | 1.4652 | Do. 6 |182 to 186 | 8.6 | .9077 | +11.5 | 1.4659 | Slight | | | | | |camphoraceous | | | | | |odor. 7 |186 to 190 | 8 | .9105 | +11.1 | 1.4673 | Strong | | | | | |camphoraceous | | | | | |odor. 8 |190 to 195 | 8.1 | .9130 | +11.7 | 1.4683 | Do. 9 |195 to 200 | 7.7 | .9170 | +11.6 | 1.4710 | Do. 10 |200 to 208 | 11.6 | .9220 | +10.4 | 1.4710 | Do. Residue |208 and | 12 | .9236 |..........| 1.4854 | Do. | above | | | | | ---------+------------+---------+--------+----------+-----------+-------------

IDENTIFICATION AND SEPARATION OF THE CONSTITUENTS.

_Pinene._--The first fraction distilling below 160° C., and which possessed an odor of turpentine, was tested for pinene by means of the nitrochlorid reaction.[27] A deep blue coloration was obtained with slight turbidity, indicating a possible trace of pinene.

_Cineol, or eucalyptol._--Tests were made in fractions 2, 3, 4, 5, and 6 for cineol, which was easily recognized by its odor. For a qualitative test the iodol reaction was used, crystals of cineol iodol which melted at 111° to 112° C. forming in each fraction. Fractions 3, 4, and 5, which smelled strongly of cineol and which doubtless contained the major portion of cineol in the oil, were assayed by means of the phosphoric acid method, as directed in the United States Pharmacopœia for 1900.[28] From these four fractions a total amount of 22.5 per cent of cineol was obtained, calculated from the original oil. This figure represents approximately the percentage of cineol in the oil, although it is low rather than high, since fractions 2 and 6 both showed the presence of cineol by qualitative tests, but the quantitative estimation in these fractions was impossible owing to the preponderance of other constituents in the fractions.

A test for terpinene in fraction 6, by means of the terpinene nitrosite reaction, produced a characteristic blue coloration, but the crystalline nitrosite would not separate.

_Camphor._--A strong odor of camphor being distinguishable in fractions 7, 8, 9, 10, and in residue, a quantitative separation was made as completely as possible by means of the “freezing-out” method. Between 186° and 190° C. some crystals of camphor began to form in the inner tube of the condenser, and at 195° C. the condenser had to be kept jacketed with steam to prevent clogging, so rapidly did the camphor distill over. The fractions above 195° C. were practically solid. The camphor which separated at ordinary temperature was filtered on a force filter, and the liquid portion of the fractions subjected to freezing successively until camphor no longer separated. It is apparent that the separation of the camphor from these small fractions by freezing out is rather inaccurate because of the losses in transferring and filtering. From the above fractions, however, a quantity of camphor was obtained corresponding to about 40 per cent of the original oil. This figure is low, for the separation on a larger scale working with much larger fractions would reduce to a considerable degree the loss of camphor which is unavoidable in such small fractions.

The fractions distilling between 195° and 208° C. yielded crystals when treated with bromin in a petroleum-ether solution of the oil. The crystals melted at 130° C. Thujone tribromid melts at 122° C. A trace of thujone is therefore probably present in the oil. It is very possible, in view of the fact that the acetylization of the oil disclosed some free alcohol, that the last fraction contained some borneol, which boils at 212° C.

SUMMARY.

The results of the experiments would seem to indicate that the oil of black sage is composed essentially of camphor (more than 40 per cent) and cineol (22.5 per cent), with a small quantity of an alcohol, probably borneol, both free and as an ester, and a small quantity of the ketone thujone, with traces of the terpenes pinene and terpinene. Free formic acid was found, and only traces of combined acetic and formic acids in the form of esters.

The constituents of possible economic importance in the oil are camphor and cineol, both of which possess considerable medicinal value, the former being used also very extensively in the arts. These constituents, possessing strong antiseptic virtues, no doubt impart antiseptic properties to the oil. Inasmuch as the yield of oil from the fresh herb approximates 1 per cent, if distilled during the full flowering stage, and furthermore, since the plant thrives on low sandy hills or wastes, it is very probable that the shrub could be grown profitably both for its oil and for the large amount of camphor and cineol capable of being isolated from it.

WILD SAGE.

BOTANICAL DESCRIPTION AND DISTRIBUTION.

_Artemisia frigida_ Willd., commonly known as wild sage, mountain sage, pasture sagebrush, and wormwood sage (figs. 3 and 4), is a hardy perennial 6 to 20 inches high, with a woody base and white silky leaves. The numerous yellow flowers, arranged in a racemelike head, possess a strongly camphoraceous odor. The leaves are also strongly aromatic. The plant abounds on dry sandy hilltops from the Dakotas west to Idaho, north into Canada, and as far south as Texas.

DISTILLATION OF THE OIL.

The oil distilled from wild sage was briefly reported by the writer in 1905[29] and 1906.[30] The promising preliminary results encouraged a further investigation of this plant. During the summers of 1907 and 1908 larger quantities of this interesting wild plant were distilled in South Dakota, a yield of 0.26 per cent of a very fragrant essential oil being obtained from plants which had passed their flowering stage. When the plant is distilled during its flowering stage the yield of oil is about 0.41 per cent.

The oil obtained by the distillation of the whole plant was beautiful pale green in color, with an agreeable fatty and camphoraceous odor and a slightly bitter camphorlike taste. The specific gravity of the oil at 24° was 0.940; specific rotation A_{D} = -24.2°; re-fraction N_{D} 24°, 1.4716. The oil was soluble in 1 volume of 80 per cent alcohol, becoming turbid in 2 volumes or over.

SEPARATION OF STEAROPTENE.

During the distillation and filtration of the oil, small crystals were observed at the mouth of the distillation apparatus and also at the mouth of the funnel after standing over night. In order to separate this stearoptene (solid portion of the oil) from the elaoptene (liquid portion) 50 grams of the oil were subjected to a freezing mixture of ice and salt for several hours. As a result crystals separated in the form of white flakes. The crystals were thrown into a force filter and weighed, a total of 3 per cent resulting.

IDENTIFICATION OF CRYSTALLINE COMPOUND.

After recrystallization of the above crystals from alcohol the properties of the crystals compared very favorably with levo borneol, as shown in Table III.

+Table III.+--_Comparison of properties of crystals from oil of wild sage and of pure borneol._