United States Patent Office Patented Aug
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2,715,627 United States Patent Office Patented Aug. 16, 1955 2 being but one of economic discretion. For example, one may elect to extract the whole, dried plant providing the 2,715,627 additional alkaloids to be obtained thereby balance eco SOLVENT EXTRACTION OF OPUMALKALODS nomically the additional solvent requirements. Charles L. Mehltretter and Francis B. Weakley, Peoria, 5 The binary solvents are composed of a major portion Eil, assignors to the United States of America as repr of a lower alkanol having at least two carbon atoms, as resented by the Secretary of Agriculture for example, the propanols, the butanols, or the pentanols, or mixtures thereof. The solvents contain a minor pro No Drawing. Application May 26, 1952, portion of water, the weight ratio of water to alkanol Serial No. 290,109 O being about 1.0 to 2.0 parts water for each 10 parts of alkanol. We prefer to employ as alkanol those in which 4 Claims. (Cl. 260-285) the solubility of water is limited, particularly those in (Granted under Title 35, U. S. Code (1952), sec. 266) which the limit of solubility lies within the designated range. An example of preferred solvent is isobutanol. Use of such solvents simplifies maintenance of the proper A non-exclusive, irrevocable, royalty-free license in the ratio of water to alkanol, for the ratio may be maintained invention herein described, for all governmental purposes, simply by keeping the solution saturated with water. throughout the world, with the power to grant Sublicenses Our binary solvents also contain an alkali, such as am for such purposes, is hereby granted to the Government of monia, or an alkali metal base. The total amount of alkali the United States of America. required is that which will convert the alkaloids from This invention relates to the solvent extraction of alka their salt forms, as they occur in the plant, to their free loids from plant materials containing them. It relates, organic base forms. Thus, the minimum amount of alkali particularly, to the extraction of morphine and associated needed for any particular quantity of dried poppy material alkaloids from Papaver somniferum, commonly known as may be readily calculated on the basis of the known or the opium poppy; and more particularly, to the extraction : estimated alkaloid content of the material. of such alkaloids from the dried stems and capsules of the The ratio of solvent to plant material and the tempera opium poppy. ture of extraction may be varied over wide ranges. For Opium, as the term is commonly used, refers to the batch extractions, we usually employ not more than about dried latex of the opium poppy. It may be obtained by 4:1 ratio of Solvent to poppy straw. This represents about incising the unripe seed capsules and collecting the latex 30 the minimum amount of solvent to give a slurry which which exudes from the incision, after it has dried. The can be stirred or agitated. Free-flowing, countercurrent narcotic properties of opium are due principally to the extractions may require greater ratios. We may use morphine, which is present to the extent of about 10 per greater proportions of Solvent to straw in our extraction cent in opium. There are numerous other alkaloids pres process, but for reasons of economy prefer to employ ent in opium which possess narcotic properties and, like near minimum amounts. The temperature of extraction mcrphine, are valuable pharmaceutically. may be any temperature from room temperature or lower The hand method of harvesting opium from poppies, as up to and above 60° C. Higher temperatures are desir mentioned in the foregoing paragraph involves a large able for rapid extractions, but efficient extraction is ob amount of hand labor and is not satisfactory in regions tained at the lower temperatures, say in 2 hrs. or less. where labor costs are significant. Numerous methods 40 Likewise, an excess of alkali over that theoretically re have been devised for extracting alkaloids from the poppy quired for the conversion may be employed, but we prefer plant. For example, since the alkaloids are concentrated to use the minimum amount, inasmuch as excess alkali mainly in the capsules, there may be crushed and extracted serves no useful purpose in the extraction. with various solvents. The poppy heads and straw may be The extract obtained according to our process may be dried and extracted with aqueous solvents to obtain an treated to recover the extracted alkaloids. The treatment extremely dilute aqueous solution of alkaloids which may may vary, numerous recovery methods being readily ob then be re-extracted with organic solvents to obtain a vious to those skilled in the art. For example, the alka more concentrated solution of the alkaloid. Alternatively, loids may be isolated by liquid-liquid extraction with aque the aqueous extract, which may be acid in character, may ous mineral acid followed by alkali precipitation. The be concentrated by evaporation and a crude opium-like : extract may be evaporated to produce a residue rich in residue obtained. - alkaloids and the residue may then be treated to recover The disadvantages of the foregoing and other prior art the alkaloids. The alkaloids may be recovered from the methods for extracting alkaloids from the opium poppy extract by ion exchange techniques, one of which is de are that the initial extracts are extremely dilute, and costly scribed and claimed in our copending application Ser. No. and tedious concentration methods are required. More- : 290,110, filed May 26, 1952, and continuation-in-part over, the residues obtained as final products are frequently thereof Ser. No. 356,918, filed May 22, 1953. The latter quite crude and require further costly separation pro method of recovery is especially suitable for recovering cedure before the alkaloids may be obtained in a satis the alkaloids from our extractions, and as described in factory state of purity. our copending application, the extraction can be carried According to the present invention, dried poppy cap out in such a manner that an alkaloid product may be re sules, which may or may not be associated with stems or covered in high purity and excellent yield by an overall event the stalks and leaves of the whole poppy plant, are process for extraction and recovery which includes carry extracted with a binary solvent, whereby an efficient ex ing out our extraction process within certain critical traction is accomplished directly and whereby a relatively limitations and combining the extraction process with a concentrated extract is obtained. The extract may be Subsequent particular ion exchange recovery. treated by known methods to recover a crude alkaloid product rich in valuable alkaloids, principally morphine The following examples illustrate our invention. and codeine. The invention will be described below as EXAMPLE 1. it is applied to "poppy Straw,' i. e., the ground poppy cap In the extraction procedure, 25 g. of dried poppy straw, sules associated with some of the stem section, but it is to which had been tempered and flaked and which contained be understood that it may be applied also to the unground 13.2 percent moisture, was mixed with the solvents desig capsules, stems, and stalks, the difference in procedure nated in the following table. The time of extraction was 2,715,627 - 3 4 : 12 hrs. After the extraction, the solvent was removed We claim: in a stainless steel basket centrifuge and the residual flakes 1. The method of extracting opium alkaloids from immediately washed with a volume of water equal to the poppy straw comprising extracting dried poppy straw with volume of the first extract. The extract and wash water a solvent comprising isobutanol and water, the weight were combined, and total solubles and morphine content 5 ratio of water to isobutanol being within the range of from were determined. The poppy straw used contained 0.52 1:10 to the point of saturation, said solvent also contain percent morphine (dry basis). - ing sufficient alkali to convert the alkaloids of said poppy Comparative extractions were made with acidified aque straw to the free base form thus to obtain an extract of ous solvents, with water-soluble organic solvents and with ... alkaloids, and recovering alkaloids from said extract. ethylene dichloride, chloroform and mixtures of chloro 10 2. The method comprising extracting dried poppy straw .. form and ethanol. The efficiency of the extraction was with a solvent consisting of water-saturated isobutanol: considered on the basis of the amount of morphine ex containing sufficient ammonia dissolved therein to convert tracted, since this is the principal alkaloid present and the alkaloids of said poppy straw to the free base form, analytical methods for the determination of morphine are separating the extract from said poppy straw and recover considered more reliable than any of the other alkaloids. 15 ingalkaloids from said extract. Table 1 . Weight percent Percent of dry : " - Solvent? of solvent straw: Morphine Solvent Ely Teap, Title, -- East, - ratio - Alkali Water Solu-E. Sulfatedash . of total Chloroform-------- .5 50 2 ------------ 0. Ill---------- - 8 Sulfuric(0.6%) acid 10 80 42 ---------- 85... ." Water--- 10 80 32 1.5 80 Do--- 10 80 35 <11. 5. 00 Isopropano 5 60 - ... 5 Tr. 50 Do--- 5 60. 2 4.9 a v. 88 Isobutanol--------- ... 5 25 4 1.0.-- 6 Do------------ 5 60 41 (NaOH) l6 -------- 10 DO- 5 60 2 1 (NH3) 13 --------|-- 00 Do 5 60 2 0.5 17 95 Do- 5 : 60 2 0.23 17 - 95. N-butan 5 60 2 0.23 20 85 EXAMPLE 2. 3. 3. The method of claim 2 in which the weight ratio of Several runs were carried out on a larger scale on poppy solvent to poppy straw is about 4:1.