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Accession number 966 d.ard/lard Research Center Greensbore INVESTIGATIONS INTO THE EXTRACTION OF NICOTINE FROM TOBACCO Submitted by: J. R. Reid Report number: Date: 2/7/77 Summary or Abstract: Investigations have been carried out to find an inexpensive and efficient method of extracting nicotine from tobacco. A survey of the literature indicated that two promising techniques were the extraction with water or freon. Both procedures have been studied and result in an 80-85% reduction in leaf nicotine. The water method yielded'directly a suitable smoking material but the nicotine recovery procedure involved elaborate pro- cessing. The freon-ammonia system afforded.the nicotine in a straightforward manner but required further develop- mental work for the tobacco to be a suitable smoking material. /lmh Xc: Dr. H. J. Minnemeyer Dr. R. S. Marmor Dr. R. W. Slaven Mr. R. L. Thomas Library

I t TABLE OF CONTENTS Page No Title Page and Abstract ................................ Introduction ........................................... 1 Organic Solvent Extraction ............................. 5 Conclusions from Freon Extractions ............. 16 Recommendations for Freon Extractions .......... 17 Water Extraction ....................................... 18 Conclusions from Water Extraction 33 Recommendations to Water Extraction 33 Conclusions to Overall.Extraction Work Performed.........33 Recommendations from Overall Extraction Work ............. 34 List of Tables ........................................... 35 List of Diagrams ......................................... 36 Appendix References

.S I LIST OF TABLES Table #' Title Page No. 1. Leaf Analysis of Freon Extracted Tobacco 6 2. Leaf Analysis of Tobacco after Sequential Increments of Ammonium Hydroxide 7 3. Gas Chromatographic Analysis of Extracts 7 4. Leaf Analysis and Recovery Volumes - Seq,uential Addition of Freon 8 5. Leaf Analysis of Tobacco from Large Scale Extraction I 9 6. Leaf Analysis of Tobacco from Large Scale Extraction II 11 7. Leaf Analysis of Tobacco from Two-Stage Extraction 13 8. Leaf Analysis of Stems from Freon Extraction 14 9. Taste Profile of Freon-Ammonia Extracted Tobacco 15 10. Leaf Analysis of Methylamine-Freon Extracted Tobacco 16 11. Sequential Extraction Scheme for Small Scale Burley Tobacco 18 12. Leaf Analysis of Sequentially Extracted Burley and Flue-Cured Tobacco 20 13. Sequential Extraction Scheme for Large Scale Burley Tobacco 22 14. Recovery of Nicotine from Sequential Extraction 23 15. Leaf Analysis of Tobacco from Partial Extraction 23 16. Leaf Analysis of Tobacco from Whole Leaf Partial Extraction 24 17. Organoleptic Evaluation of Partially Extracted Kent Burley 25 18. Sequential Extraction Scheme in Stem Extraction 27 19. Parameters of Steam Distillations 29

LIST OF DIAGRAMS Diagram #' Title Page No. 1. Steam Distillation Concentration Apparatus 30 2. Continuous Nicotine Extraction Apparatus 32

Lorillard currently desires to introduce a low "tar", moderate nicotine cigarette as a marketable sales brand. One means of accomplishing this goal is by the addition of nicotine, either as the pure alkaloid or as a salt at some point in the tobacco processing, onto a low tar, low nicotine blend of tobaccos. The nicotine requirement for the yearly support of a sales brand of 10 billion cigarettes containing 600 mg of tobacco per cigarette and an added l% nicotine amounts to 132,000 lbs/year. Our primary objective was to study the economically feasible sources of nicotine and its isolation and recovery as the pure alkaloid or as a nicotine salt. Previous estimates for the isolation of nicotine from our current stock of waste tobacco range from~40-45% of this total nicotine requirement depending upon which waste is utilized and specificaliy the efficiency of our recovery and~isolation procedures. The remainder of the nicotine must be purchased as alkaloid, alkaloid salts or tobacco suitable for extraction. This tobacco must be processed and the nicotine subsequently isolated and~recovered. Since an isolation technique would be required, we began to study a variety of published procedures for the isolation of nicotine from tobacco. The use of nicotine as a commercial insecticide has generated numerous methods for the extraction of nicotine from tobacco. All the methods for the extraction of nicotine can be broken down into four distinct categories: 1. Water Extraction. 2. Extraction with organic solvents with or without preliminary treatment of the tobacco. 3. Steam distillation directly from the tobacco. 4. Pyrolytic degredation of tobacco material and direct distillation of the nicotine. These four areas were investigated for their relative advantages and disadvantages reported in the literature. 1. Water Extraction The water extraction technique is one of the ollest methods used for the manufacture of insecticidal solutions. This technique has been performed~using either hot or cold water 3 or water which has been treated with~ alkali (ammonia, lime or lye)

The use of ultrasonication for the release of nicotine into the water has been shown to expedite the extraction process ~y rupturing "nicotine cells" within the tobacco matrix. A recent report 6 has indicated that green uncured~ tobacco can also be used. In an effort to reduce cost, a high nicotine tobacco (N. Rustica) was cut while green, water and lime were added and the juice expressed using sugar cane technology. The solutions obtained by these water extraction methods usually contain 0.1% to 1.0% nicotine plus other dissolved or suspended tobacco material. These extracts are then processed to concentrate the nicotine, either as the pure nicotine alkaloids or as a nicotine salt. The usual salt chosen has been the sulfate since aqueous solutions of this nicotine salt may be con- centrated up to 40% before crystallization occurs upon storage. These 40% solutions are then marketed directly as insecticide under the name Black Leaf 40. The reported methods for the concentration of nicotine from dilute aqueous solutions include high pressure steamm distillation from alkalinized solutions 7 and organic solvent extraction. 8 The steam distillates then require an additional concentration step which has consisted of acidification followed by distillation or solvent extraction of realkalinized solutions. The large amount of organic solvent used to extract the dilute nicotine extracts must then be either removed by distillation to afford the nicotine alkaloids 9 or sequentially washed with aqueous acid solutions until the acid/nicotine concentration reaches the desired level. 9 The organic solvents used include kerosene, 10 methylene chloride, dichloroethylene, diethyl ether 11 and chlorobenzene 9. The time required for an efficient extraction depends upon the favorability of the partition of nicotine between water2nd the organic solvent and the pH of the water or extracts 1.[See Appendix] 2. Organic Solvent Extraction Previous investigators have demonstrated that a variety of organic solvents can be used to extract nicotine from tobacco. The Vbacco can be extracted B rectly with methylene chloride or methyl ethyl ketone continuously to effect an excellent removal of the nicotine. The tobacco has also been treated with ammonia, lime or lye then extracted with other organic solvents, such as tr}S hloroethylyle, benzene, gasoline, kerosene, diethyl ether or freon .

3 In the case of the organic solvents immiscible with water, the extracts can be reextracted with aqueous sulfuric acid solutions until the desired concentration is reached'. The organic solvents are recycled for further extraction. The methyl ethyl ketone extract was processed in a unique manner. The nicotine was reextracted from the organic solvent by the use of cold saturated aqueous salt solutions. The two phases were separated and then warmed, the salt phase was rendering the nicotine immiscible. The impure nicotine was separated as a distinct dark phase at the surface of these mixtures. 15 The organic solvents boiling lower than water also permitted direct fractional distillation~ to afford more concentrated solutions of nicotine since the heat requirement for concentration was substantially decreased. 3. Direct Tobacco Steam Distillation The nicotine can also be extracted from the tobacco by direct steam distillation. With the exception~of a small percentage of "free" nicotine, the maj?Eity of the nicotine in tobacco is bound as organic salts. These salts have been neutralized by the use of lye or lime and the nicotine distilled from the tobacco directly by the use of steam. Again the distillate is a very dilute solution of nicotine in water and required further processing as described earlier. The tobacco and stem material can be powdered to effect a more intimate contact between the alkali and the organic acids and thus free the nicotine 17 or alternately the alkali treated tobacco can be placed under a vacuum followed by a rapid release. This will rupture the nicotine cells, the nicotine from which is then~steam distilled. 18 An alternate procedure was used in~which a stream of ammonia was introduced continuously into a steam distillation apparatus. 19 The condensed distillate was then fractionally vacuum distilled to remove ammonia dissolved in the con- densate. 4. Dry Distillation~ The dry distillation technique has reportedly been used successfully on waste tobacco. 26 Tobacco material is treated with alkali and can be heated in a rotating drum with either vacuum~or a slow heated air steam being passed through. The nicotine volatilizes and is passed into a series of condensing traps. 21 By this technique various tobacco wastes were processed for their nicotine content. All volatiles pass over and a purification step, usually vacuum distillation, is required for the recovery of the nicotine alkaloids. At these higher temperatures, more nicotine is thermally degraded as well as the generation of undesirable pyrolysis products from the tobacco material. 22

4 It was felt that for the nicotine recovery system to be operated economically, the method chosen should cause little or no injury to the tobacco material. This would allow the tobacco, after extraction, to be reused for blending into a low "tar", low nicotine blend. Of the methods outlined, the two causing the least amount of damage to the tobacco are the water extraction technique and the organic solvent extraction technique. Our preliminary investigations into the dry distillation of tobacco 23 and direct steam distillation of leaf material 24 were not encouraging. The nicotine recovery was very low and the processing resulted in partial or complete destruction of the leaf material. These procedures would not be appli- cable to the extraction of nicotine from reusable leaf material, however, they might find utility in the recovery of nicotine from stems, dusts, or sands. Although there i~~an attractive patent making use of supercritical fluids it was not possible to investigate the use of extraction techniques employing them due to the unavailability of the high pressure equipment need for a laboratory evaluation. This report deals primarily with our investigations into the water extraction techniques and the extraction of nicotine from tobacco with organic solvents.

5 Organic Solvent Extraction The use of organic solvents to extirt nicotine directly from tobacco has been well documented, however, recently most of these solvents hav e been under investigation as to their adverse toxicological properties. If the tobacco is to be reused as a smoking material, the solvent residue levels remaining must be minimal and harmless. Preliminary investigations into the choice of solvent included a isooctane/heptane system. The isooctane/heptane extraction system seemed to be only moderately efficient yielding only a 64% reduction in the leaf nicotine. The recovery of the nicotine from the solvent was excellent and' produced an overall 63%' recovery as the sulfate. 26 The use of kerosene or gasoline would leave large hydro- carbon~residues which would not only be highly flammable but might render the tobacco useless. Based on a patented procedure 15 we investigated the methyl ethyl ketone - brine extraction system. A four-fold extraction of tobacco with methyl ethyl ketone extracted over 85% of the leaf nicotine. The methyl ethyl ketone was extracted with cold acidic brine. The brine extract was made alkaline with sodium hydroxide and'warmed. This caused the nicotine to separate as a distinct upper phase which was separated. Upon analysis this phase was shown to be 20% nicotine giving a recovery of 82% from the leaf. In order to isolate the pure alkaloid a purification step would be required from this recovered concentrated nicotine upper phase. The experimental details of this extraction and the isooctane-heptane extraction have been reported previously. 26 Methyl ethyl ketone, chloroform, methylene chloride, tri- chloroethane and dichloroethane have been shown to be, or are suspected of being, carcinogenic agents. Freon 11 offered a solution to this problem in spite of current environmental controversy. The low boiling point (24°C) would enable volatilization with a minimum of heat and leave a very minimal residue on the tobacco itself. Since we currently use freon 11 in our puffing process the technology for handling and recovering large volumes of this solvent from tobacco is readily available. The following experiment, based upon a patented procedure,14 was performed in order to determine the relative efficiency of nicotine extraction from leaf material by freon 11. A 300g portion of Burley tobacco, Grade HH, was coarsely chopped and mixed with 60 ml of water. After standing for 30 minutes 1.75 Q of freon 11 was added. This suspension was allowed to stand for 30 minutes at 20°C then the tobacco was filtered through cheesecloth. After air drying in a hood for 24 hours the tobacco was then~analyzed for nicotine content. The freon was extracted with two 25 ml portions of 30g aqueous citric acid solution and analyzed by capillary gas chromato- graphy. 27

The following table lists the results: TABLE 1 Leaf Analysis of Freon Extracted Tobacco Tobacco or Extract % nicotine % total nitrogen Burley, Grade, HH 3.23 4.79 Grade HH, Extracted 3.30 4.67 The citric acid solution was found to contain 230 mg nicotine corresponding to ti 2% of the total leaf nicotine available. This correlates quite well with the amount of "free nicotine" found on burley tobaccos.28 One major deviation from the patented procedure was the use of 20°C at atmospheric pressure. The literature claims to have used 64°C at 40 psi. This work indicated'that freon 11 would not extract any appreciable amount of nicotine from the tobacco when used at room temperature and~pressure. It was felt that the nicotine could be extracted if the tobacco were first treated with alkali strong enough to release "bound" nicotine. For this reason ammonia was chosen and the following series of experi- ments performed to roughly determine the relative amount needed for efficient extraction of the nicotine fr=the tobacco. For the ammonia study the solvent used was not freon but rather methylene chloride. Even though this solvent would not be used for our large scale extraction process the lower volatility and very similar extraction properties made it possible to rapidly analyze the extracts directly for nicotine without solvent volatilization errors or subsequent acid extraction error. A 200g portion of coarsely chopped burley tobacco, was mixed with a solution of the desired amount of concentrated ammonium hydroxide (28.4$ ammonia by weight, d = 0.90 g/ml) which had'been diluted with water to 50.0 ml. After 30 minutes 500 ml of methylene chloride was added to the mixture. This suspension was allowed to stand for an additional 30 minutes in a covered beaker with no agitation. The solvent was filtered through cheesecloth and the tobacco pressed. The solvent was analyzed directly for nicotine. 27 The tobacco was air dried in a hood for 24 hours then submitted for leaf analysis. The results of these series of experiments are listed'in Tables 2 and 3. The maximum extraction efficiency for this one extraction system, using a minimum of solvent, was reached when approxi- mately 3.2g of free ammonia per 100g of tobacco was used at this 25% ' moisture level. This level corresponds to approxi-