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T H E J O U R N A L OF I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y
Vol. 13. No. 6
Yield and Composition of Wormwood Oil from Plants a t Various Stages of Growth during Successive Seasons1 By Frank Rabak OFFICEOF DRUQ, POISONOUS AND OIL PLANTINVESTIGATIONS, BUREAUOF PLANTINDUSTRY, WASHINGTON, D. C.
The plant Artemisia absirtthium L., commonly known as wormwood, which is found growing wild in European countries and cultivated in several localities in t h e United States, principally in Wisconsin, Michigan, a n d New York, yields upon distillation a volatile oil of considerable importance. For the production of the oil of commerce t h e whole flowering plant is distilled in the fresh condition. The oil is described as a brownish green liquid with a strongly aromatic, unpleasant odor a n d bitter taste, the principal constituents of which are thujone (absynthol), thujyl alcohol, esters of thujyl alcohol, phellandrene, pinene, and cadinene. The oil is used principally as a medicament for both internal and external application. DISTILLATION
O F PLANTS
tation, average mean temperature, clear, partly cloudy, a n d cloudy days. The figures given represent t h e conditions during the growing months of April, May, June, a n d July, before harvest and distillation. TABLE11-COMPARISONOF YIELDS OF OIL WITH CLIMATIC CONDITIONS DURING APRIL, MAY,JUNE,AND JULYFROM 1907-1919 Average -Weather ConditionsYield PrecipitaMean Partly of Oil tion Temperature Clear Cloudy Cloudy YEAR Per cent Inches Degrees Days Days Days 15.05 62.2 48 41 3a 12.72 67.7 42 57 23 12.08 66.5 47 48 27 18.47 67.0 59 37 26 10.04 68.2 54 35 28 18.82 66.7 57 33 23 36 42 15.49 53 67.7 13.99 67.7 42 47 33 14.01 67.0 35 48 39 19.67 67.0 34 42 46 17.31 66.0 36 54 32 15.31 67.0 38 46 38 17.44 67.5 38 34 50
It will be noted t h a t t h e highest yield of oil in most cases was during those seasons in which t h e precipitation was lowest, this being especially true of the years 1908, 1911, and 1914. It is also significant t h a t t h e highest mean temperature prevailed during these seasons. Some relationship also apparently exists between t h e clear, partly cloudy, and cloudy days and the yield of oil. The greater the number of clear and partly cloudy days, t h e greater was the tendency of t h e plants t o high yields of oil. High precipitation a n d low temperature, together with much cloudy weather, a s in 1915, 1916, 1917, a n d 1918, apparently tended toward low content of oil. Such a combination of conditions would be conducive t o high moisture content in the plants, thereby increasing the weight of the plant and lowering t h e yield of oil. Under the same conditions it also appears t h a t stimulation of the plant with regard t o t h e formation of the volatile oil is likewise retarded. I n general, i t may be stated t h a t the yield of oil from wormwood is dependent upon the particular combinaTABLE I-YIELD OF WORMWOOD OIL FROM FRESHAND DRY FLOWERING tion of climatic conditions existing during each growSUCCESSIVE YEARS HERB DURINQ SEVERAL (All yields of oil calculated on basis of fresh herb) ing season, a n d will vary from year t o year in propor1907 1908 1909 1910 1911 1912 1913 1914 1915 1916 1917 1918 1919 Av. tion t o the varying conditions of precipitation, temFresh Herb perature, a n d sunshine. 0.12 0.18 0.13 0.200.21 0.17 0.15 0.24 0.15 . . 0.15 0.14 0.16 0.166 EFFECT O F DRYING-Discussing further the results Dry Herb 0.09 .. 0.11 .. 0.050.16 .. .. 0.08 .. .. .. .. 0.098 in Table I, i t is apparent t h a t drying of t h e plants A study of Table I shows t h a t the yields of oil from before distillation invariably results in a loss of volatile oil, causing, thereby, a decrease in t h e percentage of t h e fresh herb differ considerably from year t o year. oil. The average yield of oil from fresh flowering This observation is of material interest since t h e plants herb during the seasons 1907 t o 1919, inclusive, was were cultivated during the whole period of years on 0.166 p r r cent, while t h e yieId of oil from dry herb was t h e same heavy clay soil with approximately the same 0.098 per cent. T h e average yield of oil from the dry fertility. Since all conditions were practically alike, herb is, therefore, approximately 41 per cent lower i t may be concluded t h a t t h e variable yields of oil were t h a n the yield from t h e fresh herb. due entirely t o climatic conditions. EFFECT OB CLIMATIC CONDITIONS-FOr the purpose Of PHYSICAL AND CHEMICAL EXAMINATION OB OILS FROM FRESH AND DRY FLOWERING HERB correlating t h e yields of oil from the fresh flowering I n order t o study further the effect of seasonal herb with the climatic conditions which prevailed during the several seasons, Table I1 was prepared. The par- changes and drying on the plants, determinations were ticularqnconditionstaken into account were the precipi- made of the physical properties of the oils and also the percentage of free acids calculated as acetic acid, esters 1 Reqeived February 21, 1921. T h e following observations were made with wormwood under cultivation a t the Arlington Experimental Farm, Arlington, Virginia, for a period of years. During t h a t time the plant was distilled both in the fresh flowering a n d in the dry condition, and also a t different stages of growth. A number of t h e oils obtained were subsequently examined in the laboratory a n d compared from t h e standpoint of their physical and chemical properties. As the volatile oil is contained in both t h e flowers and leaves, the whole plant was distilled in every instance. Distillations were made of both fresh and dry plants in order t o ascertain the effect on yield and quality of the oil. Since the oil is distilled commercially during t h e flowering stage of the plant, this stage was selected in making the following comparisons as regards yield of oil. The conditions of distillation in every instance were identical, the same distilling apparatus a n d like steam pressure being employed each year. T h e results of the experiments are embodied in Table I.
June, 1921
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TABLE 111-PHYSICAL PROPERTIES, ACID, ESTER, A N D ALCOHOL CONTENT OF WORMWOOD OIL FROM FRESH AND DRYFLOWERING HERBDWRING SEVERAL SUCCESSIVE SEASONS
Physical Properties, Acid, Ester and 1906 Alcohol Content Fresh Color Dark brown
-1907
Odor
Very strongly aromatic
Taste
Bitter, pungent
Specific gravity Solubility in alcohol
0.9251 3 vols. 90 per cent alc. with clear sol.
Free acids as acetic (per cent) Esters as thujyl acetate (per cent) Alcohols as thujyl alcohol (per cent) 1 At 25' C. 1 At
TABLE IV-YIELD,
1908
Fresh Dark brown
Dry Nearly black
I910
1
0.91691 0.9351 0.93082 1 vol. 80 per cent 1 vol. 80 per cent 1 vol. 90 per cent alc. with clear sol.
alc. with clear sol.
0.92748 0.92649 0.94202 1.2 vols. 80 per 1.2 vols. 80 per 0 . 5 vol. 80 per cent cent alc. Clear with more alcohol
cent alc. Clear with more alcohol
alc. Clear with more alcohol
0.15
0
0
0
31.8
32.2
35.0
32.5
24.1
27.3
33.2
15.6
13.8
11.6
19.3
21.5
13.8
16.6
23' C.
PHYSICAL
8
'
alc. with clear sol. Turbid with 10 vols.
0.14
PROPERTIES, ACID, ESTER, AND ALCOHOL COXTENT OF WORMWOOD OIL
0.10 Dark brown; rather pleasant characteristic odor, extremely bitter, slightly pungent taste
Flowering
0.20 Dark greenish brown; strong aromatic not unpleasant odor;
Fruiting
0.08 Dark brown; pleasant characteristic aromatic odor; slightly
very pungent taste
bitter aromatic and strong pungent taste bitter pungent aromatic taste At 23' C.
of thujyl alcohol as thujyl acetate, and alcohols as thujyl alcohol, in the oils. The results of these determinations are shown in Table 111. No material differences are observed in the color, odor, and taste of the oils distilled from the fresh herb during the five successive seasons beginning in 1906. The colors range from,a dark brown t o a dark brownish green, and the odors differ principally in their intensity. The specific gravity and the solubility of the oils show appreciable differences, indicating differences in composition. .The percentage of free acids in the oils from the fresh herb varies considerably. The contents of esters as thujyl acetate are in close conformity, with the exception of the oil from the 1909 crop, which shows a decided decrease in these constituents. The greatest differences in the constituents appear t o be in the thujyl alcohol content, which ranges from 11.6 t o 19.3 per cent. High ester content in the oils appears t o be accompanied by correspondingly low alcohol content, a n d vice versa. The oils distilled from the dry plants are uniformly darker in color and stronger in odor than those distilled from the fresh plants; and the thujyl acetate content is higher than t h a t of the fresh herb in both 1907 and 1909, while the thujyl alcohol content, on the other hand, is higher only in the oil from the 1909 crop. Observations on a larger number of oils from dry plants would probably show that these oils differ noticeably from the oils from the fresh plants, as shown by the marked divergence of the 1909 oil. During the seasons of 1908 and 1910, the whole, fresh
Specific Gravity
FROM
0.25
FRESH HERBAT VARIOUS STAGES OF GROWTH
Solubility in Alcohol
0.92731 10 vols. 90 per cent alc. with turbidity
0.93081 1 vol. 90 per cent alc. with 0.949'
clepr solution. with more alc.
Turbid
0.5 vol. 90 per cent alc. with clear solution.
-
4 vnk
0.14 Dark brownish green; strong aromatic odor; bitter aromatic,
At 24O C.
0.21
A t 21' C.
Budding
At 22O C.
1910
Fresh Dry Fresh Dark brown with Dark brownish Dark brownish green green tint black Strong, penetra- Fatty, strongly Strongly character- Strong, unpleas- Very strong un- Characteristic, aroting, aromatic aromatic, disistic but not disa n t , aromatic pleasant, aromatic, not unagreeable agreeable matic pleasant Bitter, pungent Aromatic, slight- Bitter, pungent, Very bitter, aro- Very bitter, aro- Bitter, aromatic, aromatic ly bitter matic matic very pungent
Yield of Oil Color, Odor, and Taste YEAR Material Per cent 1908 Budding 0.17 Dark brown: strongly-aromatic, disagreeable odor; pungent aromatic taste Flowering 0.18 Dark brown; strongly aromatic, not unpleasant odor; bitter pungent aromatic taste Fruiting
1909
r
Fresh Dark brown
Turbid in
Free Esters as Alcohols Acid as Thujyl as Thnjyl Acetic Acetate Alcohol Per cent Per cent Per cent
.. .. ..
0.9594s 1 vol. 80 per cent alc. with 0.30
clear sol. Clear with more alc. 0.94208 0.75 vol. 80 per cent alc. with 0.26 clear sol. Clear with more alc. 0.94108 0.5 vol. 80 per cent alc. with 0.07 clear sol. Clear with more alc.
26.0
14.7
32.5
11.7
47.5
12.0
48.6
16.8
33.2
13.8
37.10
13.18
wormwood plants were distilled a t three stages of growth, namely, budding, flowering, and fruiting, in order t o study the resultant oils as they occurred in the plant a t these distinct stages of maturity. The yields of oil and the physical and chemical properties are tabulated for comparison in Table IV. It will be observed from Table I V t h a t the maximum yield of oil is attained in the plant during its flowering period. A decided decrease in oil content is noted during both seasons in its fruiting stage, being considerably lower in yield a t this time of growth than in either the budding or flowering stages. Only minor differences are evident in the color, odor, and taste of the oils, and no definite relationships seem t o exist in their specific gravities. A uniform increase, however, in solubility of the oils from the plants during both seasons is noted, especially in 1908. It will be seen, however, t h a t the oil from the budding stage of plants in 1910 is much more soluble in alcohol t h a n t h a t from the same stage of growth in 1908. Increase in solubility of the oils appears t o be accompanied by a high percentage of esters, since the content of thujyl acetate is greatest in the oils most soluble in alcohol. It may also be pointed out t h a t a fiigh percentage of thujyl acetate in any of the oils is invariably accompanied by high specific gravity, and vice versa. The content of free acids (as acetic) in the oils from the 1910 crop diminishes as the plants mature. The relationship between the alcohol content and the solubility and specific gravity is not so marked. There is, however, a decrease in the percentage of thujyl alcohol during both seasons as the plants pass from the budding t o the fruiting stage.
T H E J O U R N A L OF I N D U S T R I A L A N D E N G I N E E R I N G ’ C H E M I S T R Y Vol. 13, No. 6
538
co~cLusIo~s 1-The yield of oil from the fresh herb during its flowering stage varies greatly from year to year, owing entirely t o varying climatic conditions. Low precipitation, coupled with high temperature and much sunshine, affects the yield of oil favorably, while converse conditions cause a lower yield. 2-Drying of the plants before distillation invariably causes a reduction in the yield of oil, but apparently promotes esterification in the oils. The ester constit-
uents of the oils from the fresh herb over a period of years appear to be in closer conformity t h a n the alcoholic constituents. 3-The highest yield of oil is obtained during the flowering period of the plants. Solubility of the oil in alcohol apparently is a criterion of the percentage of esters present. Likewise, specific gravity bears a close relationship t o the ester content of the oils. The alcoholic constituents decrease as the plant approaches maturity.
Studies in Synthetic Drug Analysis. VIII-Estimation of Salicylates and Phenol‘ By W. 0. Emery SYNTHETIC PRODUCTS LABORATORY, BUREAUOR CHEMISTRY, WASHINGTON, D. C.
The estimation of salicylates in general, and of salol, phenol, salicylic acid, aspirin, etc., in particular, are constantly recurring problems, the satisfactory solution of which depends in large measure upon the nature of the preparations in which such medicaments occur, whether alone or in simple admixture with inert materials susceptible of easy separation, or again in more complicated mixtures containing, besides vehicular matter, combinations of several therapeutic agents. I n a former paper,2 one of the two procedures outlined involved the alkaline hydrolysis of salol preliminary t o its separation from phenacetin by the aid of immiscible solvents, t h e subsequent steps constituting in principle, in so far as they related t o salol, the wellknown Koppeschaar method. While a similar or slightly modified procedure can undoubtedly be applied also t o mixtures in which the phenacetin is replaced in whole or part by acetanilide, i t not infrequently happens t h a t knowledge of the salol content appears desirable without the necessity of first eliminating the accompanying medicaments, particularly in preparations which involve not only acetanilide but phenacetin and caffeine as well. With this object in view, and in the belief also that most cases of drug analysis are facilitated in proportion t o the number and accuracy of alternative methods available for the solution of any given problem, advantage has been taken of the characteristic behavior of salol, or rather its constituent elements, phenol and salicylic acid, toward iodine. The final product of such action in t h e presence of alkali or alkaline carbonates is a purplish red amorphous compound3 having the composition CsH2120,and variously termed diiodophenylene oxide, tetraiodophenylene oxide, and tetraiodophenylene quinone, the derivation of which may be represented in the following manner: 1 Received
February 11, 1921. Emery, Spencer and LeFebvre, “Estimation of Phenacetin and Salol JOURNAL, 7 (1915), 681. in Admixture,” THIS 8 The formation of this substance, first reported by Lautemann, Ann., 120 (l86l),309,and later corroborated by Kekul6, I b i d . , IS1 (1864). 221, was observed in studying the iodine substitution products of salicylic, acid. The same compound was more fully described by Kammerer and Benzinger, Bcr., 11 (1878),557, who operated with iodized potassium iodide on phenol in hot aqueous soda. Bougault, J . pharm. chim., 16128,147,was apparently the Erst to suggest its use in a gravimetric way, employing it successfully in estimating salicylic acid admixed with either benzoic or cinnamic acid.
+ 4NazC032CsH2120 = + 8NaI + 4co2 + 4Hz0 2CeHd(OH)C02H + 612 + 4NanC03 = 2CeH2120 + 8NaI + 6CO2 + 4Hz0 +
~C.SHSOH 612
from which i t appears t h a t every molecule of salol is capable of yielding two molecules of the iodine derivative, expressed in its simplest form. Irrespective of the chemical constitution-whether an oxide or quinone in character-the physical properties are such as t o warrant its analytical application not only in cases involving salol, but also as a check on the various methods hitherto employed t o determine salicylic acid and phenol. EXPERIMENTAL
The tabulated data are representative of several hundred determinations carried out on both control and commercial mixtures. The individual products required for these controls were checked as t o purity, being selected from both domestic and foreign brands. I n general, the treatment consisted, in the case of pills and compressed tablets, in triturating with or without sand, exhausting the finely powdered sample with chloroform, then, after dissipation of the solvent, hydrolyzing the residue (in the case of salol) with aqueous sodium hydroxide, heating with iodine in the presence of sodium carbonate, and finally filtering, drying, and weighing the precipitate. RESULTSOBTAINEDON CONTROLS Salol Acetanilide Phenacetin Caffeine CRHZIZO Salol No. Gram Gram Gram Gram Gram Per cent 0.3209 99.9 1 0.10 “R” 99.6 0.3201 2 0.10“M” 0.3211 100.0 3 0.10 “C” .. 0,3203 99.7 4 0.10 “C” o:io 0.3204 99.7 0.20 5 0.10 “C” 0.3220 100.2 0.50 6 0.10 “C” 0.3220 100.2 0.10 7 0.1O“C” o:io .. 0.3217 100.1 0.10 0.30 8 0.10 “C” 0.3207 99.8 0.20 0.20 9 0.10 “C” 0:05 0.3214 100.1 0.25 0.20 10 0.10 “C” 0.3215 100.1 0.25 0.20 11 0.10 “C” 0.10 0.3216 100.1 0.10 12 0.10 “C” 0.3219 100.2 0.30 13 0.10 ‘“2” 0.3225 100.3 0.50 14 0.10 “C” Phenol cryst. 0.3627 99.1 .. 15 0.10 “K” 0.3648 99.8 16 0.10 “M” Salicylic acid *. 0.2471 99.2 17 0.10 “K” 99.3 0,2474 18 0.10 “Mt” 98.9 0.2464 19 0.10 “Mk” Acetylsalicylic acid 99.3 .. 0.1897 20 0.10 “D” 99.2 0.1894 21 0.10 “B” 99.4 0.1899 22 0.10“H” 99.9 0.1905 23 0.10 “E’.’ Sodium salicylate 0.2115 98.4 24 0.10 “ M k ” 0.2136 99.4 25 0.10 “K”
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