March 19U2 E-561 UNITED STATES DEPARTI-ffiNT OF AGRICULTURE BUREAU or ENTOMOLOGY AlID PLANT Q.UARANTI1^ A REVIEW OF INFORMATION ON NORNICOTINE By L. N. Markwood, Division of Insecticide Investigations Contents Page Introduction 2 Physical properties 3 Occurrence ^ Synthesis 10 Analytical determination ik Pharmacology I5 Patents 19 Reviews and popular accounts 19 Summary 19 Literature cited 20 <;\ /■. Introduction 7orr.icotine is a licuid alkaloid, closely related to nicotine "both in ch-mical structure and in phj'sio'^Oe^ical "behavior. It occurs in ordinary tobacco, Nic otiana ta bacuru L., in other species of I:T icotian a, and in a.t least one other plant as well, viz, P-gboisia hopyroodii F. Mue].l .■ Nornicotine is an alkaloid of relatively recent history. The vrord nornicotine, which means the normal or parent form of nicotine, apparently first occurred in chemical literature in 1879 '''hen Andreoni (5a) attempted to make it from nicotine by the action of hydrochloric and hydriodic acids. Pictet and Rotschy (30) in I9OI also ref-^rred to nornicotine. The first actual claim for its existence appeared in I927 on the part of M. and II. Polonovslci (32,33) > ^''^0 described a method for preparing various nor- alkaloids, of which nornicotine was one. In 1928 j^hrenstein (lO-, ll) re- ported finding it in tobacco. In 1930 Von Braun and Weissbach (5) obtained it by demethylating nicotine. Since then a nijjnber of papers dealing with nornicotine have appeared. The most important contributions have been made by Spath and coworkers (3S to Ub) , vrho have greatly elaborated the entire field of tobacco alkaloids. The relationship between nicotine, CioH]^i:|.F2> ^^^^- nornicotine, CqHi2?l2, is seen from the- structural formulas. H2 Ho p-p. ITicotino Nornicotine Where nicotine has a mcthvl group joined to tho pyrrolidine-nitrogen atom, nornicotine has a hydrogen atom; • The latter alkaloid- is therefore a secondary- tertiary base, in distinction from nicotine, which is ditertiary. Because of its secondary character nornicotine enters into a number of re- actions j-rhich are not possible for nicotine. A more descriptive name for nornicotine is beta-pyr idyl-alpha-pyrrol idine, or 2-( 3 '-pyridyl) pyrrolidine . Nornicotine, like nicotine, is optically active. All three forms, d- , 1-, and dl-, occur in nature rnd have also been synthesized. The most prominent source of nornicotine, from tho standpoint of present available supply, is ordinary tobacco, Nipotiana tabacum . The pro- portion of nornicotine in tho total alkaloids is variable; in most strains the percentage is low, being of tho order of r fe--' percent, but it can also occur in nuantities up to 95 pore mt of the total alkaloids. The latter case is apparently connected with low-nicotine tobaccos. Tho 1-form is th principal isomer occurring in tobacco, but t.he dl-form 0.I50 occurs. W. silv_estri^ Speg. and Comes is a plant also containing a notable auantity of the 'l-"form of nornicotine, which is usuo.lly the predominating alkaloid therein. Other species of tii_co_tiana no doubt contain this alka- loid, but for the most part their alk; loidal nature 1^^' not been completely investigated. II e ka'' not ll - 3 - Both d-nornicotine and dl-nornicotine occur ir. the Australian plant I>.iboisia ho"owoodii. Physical Properties Nornicotine i"; a colorless, hygroscopic, sonie^'hat viscous liquid '•^ith a c^lij'icht amine odor v/hich is definitely less pungent than the odor of nicotine . It a;>Tpears to be more stable than nicotine, as it colors only moderately (yellow) in a clear-^^jlass bottle ex-oosed to lirht, and ■^■'ith accer.s to air. It is miscible vdth crater and oriranir solvents in ■ ill proportions. Strong alkali causes it to se-parate from anueous solu- t .' ':-ns . It ii- only slightly volatile with steam, in which respect it differs from nicotin-?, which is r.^adily volatile?. This difference has been utiliz-ed in separating the two bashes. The picrate of nornicotine is more-, soluble than thot of viicotine; a diff^->rence vrhich hur, also served in the repi^ratir;;! of the,:e bases. The most trastworthy value? of the phyr^ical -propertie.s of nar- nicotine have been selected from the literature and are recorded belov;. Although such proporties do not usually vary -ath cntic-al isonors, the nature of the isomer is notv^d with the value cited. ThQ values for nicotine are also rccord'^d, for coinparison. Specific .gravity dj'"''^= 1.0737 (Ehrcnstein, I3) . 1 and dl :20 = 1.07 (Smith, 37). 1 a d "^ = 1.070 (STjsth .and Zajic, 4b^ . 1. d^*-* = 1.070 (Spath, Iferion, and Zajic, ^^5) . 1. ^-1 = 1.0737 (Hic^-:s and ';oko?Kurlor, 18). d c-.nd dl. d^° = 1.072 (Spath, Hici:s, and Zajic, 3S) • ^^ llicotino, dg^ - 1.0092. "Boil ing goi nt 130.5-131.3° at 11 m\. (Ehrenstein, I3) . 1 and dl . 13l4_133° " ;:„t 1'- rim. (Ehrcnstein, 13) . 1 ixrA dl . 139-lUo'' at 1?. mm. (Craig, 7)- cil . 139-lUO° at 12 mm. (von Braun and Weissbach, 3)- -- ^"'i ''^^- • 266-267'' at atm. pres. (von Braun and Weissbach, 3). 1 and dl. 270-271° at atm. r^res. (Smith, 37). 1. 266-26^° at atm. pres. (llicks and LeMcssurier, IS), d and dl . 117= at '-^.35 nun. (Hicks and LeMessurier, 18). d and dl . U7'^ at\3.6 mm. (Spath, Hicks, end. Zajic, 3S) . d and dl Nicotine, 2i5^i''oi at 7!+3 mjn.; 12^*= at 2-3 mm. . u- Refraetive ind ex nJ^-^ = 1.5378 (Ehrenstein, 133. I and dl. nJ^-^ « 1.5^90-1.5518 (Hick* And leMessurier, IS), d and dl. nJ^'^ = 1.5'430 (Spiith, Hicks, and Zajle, 3S) . d and dl. Nicotine, np= I.53OO. Optical rotation [alpha]§^ = -8&'.8« (Spath and Zajic, U6) . 1. [alpha]^"' = +86.3° (Spath, Hicks, and Zajic, 39). d. Nicotine, [alpha]§^ « -I69.3*. Ultra-violet rib sorption Maximum at 2b00 A.U.; log e » 3«15 (Hicks and Lel-Iessurier, 18). d and dl. $7icotine, maximum at 260^ A.U.; log e = 3.37. Occurrence Ehrenstein (lO, ll) in 192S presented preliminary results of an investi^a-tion of the secondary allcaloids of tobacco. A further statement (12) appeared in 1930, and in I931 (l3) a complete account of his work appeared. He reported the finding of tv;0 nev alkaloids in tobacco, one of v'hich waB 1-nornicotine. The existence in tobacco of alkaloids other than nicotine goes back to Pictet and Rotschy (30) , vrho in I9OI reported finding three new alka- loids. One of these was called "nicotcine", b. p. 266-7°; the formula ^10^T2^^2 ^^^** structure ^^ 1' 11 were assigned to it, vN.>^ Noga (28) in 191^^- confirmed the presence of this body. Ehrenstoin, however, doubted the purity of '•nicoteine" and reinvestigated the matter. He readily obtained a fraction of alkaloids, b. p. 269-70°, which corresponded well v/ith nicotcine. A methylimino (N-CH-z) determination was negative, however, and hence the structure assigned above was incorrect. He found tlriat both from the steam-volatilo and the nonvolatile portions of the original tobacco extract this fraction of alkaloids could be isolated. After several fractionations of the crude base by distillation, the picrato was precipitated eind then fractionally -crystallized from different solvents. In this i/ay two different picrates were obtained, a higher-melting one corresponding to a higher-boiling alkaloid and a lower- molting one corresponding to a lover-boiling alkaloid. The former of these is not considered hero, except to note that ho concluded it was anabaoine, which v;as an error, as Spath and Kesztler (^-2) later showed it was anatabine. O' / A 5 - The lower-'boiling alkaloid was found to be l-nornicotine, CqH]^2^2j b. p. 130.5-131.3° (11 mm.) or 13^5° (1^ mm.), dJ9-5 = 1.0737, [alpha]g^ = -17.70°, N^^O = 1.5378. It was a nearly colorless liquid of a slight amine odor, v;hich liardly colored after 1 year in a sealed tube. The HCl salt was dextrorotatory'-. Oxidation with ELJOv gave nicotinic acid; the U-CHv determination showed absence of alkylated nitrogen. The methiodide derivative made from it was identical in properties v;ith the corresponding derivative maide from nicotine, as shovm by the following scheme: CH3I Nicotine (HI formed in the case of nornicotine) Nornicotine Other compounds made to characterize the base were: picrate, m. p. 191-2°; picrolonato, m. p. 250-2°, urea, m. p. l67-70°; phenyl thiourea, m. p. 176-7°. The natural l-nornicotine isolated here agreed well in properties v;ith that already report 3d by von Braun and Weissbach (5), which v/as made by deraethylating nicotine. Ehrcnstein quantitatively de- hydrogenated nornicotine over ?t-asbcstos at 320-30° to 2-[beta-pyridyl]- pyrrole, or nornicotyrine. J I. -D. 100-102' picrate m. p. 202-3°. By this investigation Ehrenstein proved for the first time the presence of nornicotine in tobo-cco . Shmuck (35) i^ 193^ published results on the investigation of several species and hybrids of Ni cctiana . The chief feature was the attempt to characterize the several types by division into steam- volatile and nonvolatile alkaloids. The following tabic' illustrates the character of the data in the paper. Plant Nicotiana alata Link ?-nd Otto ^- longiflora Cav. P et-gnia vio lacea L indl . N. glauca G-ra.ham I- !■ N, II, N, silvestris Speg. and Comes glutinos a L. tabacum L . tabacum x N. s ilvest ris tabacum x N . ^■' a uca Total Alkaloids alkaloid content Volatile Nonvolatile Percent Percent Percent 0.1130 0.0 100.0 .0766 0.0 100.0 .1201 0.0 100.0 .^77^ 23.8 76.2 ■ 5577 11.8 88.2 .33^^2 0.6 99.^ 1.9'4 100.0 0.0 • 91 2U.6 75.^ .19 80.0 20.0 r-:i Pi crate, , m. 207- -8° 176- -8° 208- -10° 218- .90 198- -200' 178- -80° - 6 - The division of alkaloids into volatile and nonvolatile groups has a "bearing on their nature in that nicotine is readily volatile with steam while the other tohacco alkaloids are much less volatile, although still volatile enough on prolonged distillation td he detected in the distillate, The ahove tahle shows complete volatility of the alkaloid of N. tahacum , which is indicative of nicotine only. The first three plants, of minor interest here, have completely nonvolatile alkaloids; their study may be interesting in other connections. Three species, N. glutmo sa, N. sil- vestris , and N. glauca , are of great interest because of their high total alkaloid content and their high proportion of nonvolatile alkaloid. Shmuck did not positively identify .any of the alkaloids except nicotine. However, in the follovdng table, which gives the ;:ieltin'g points of the picrates of the volatile alkaloids, some insight in gained into their character. Volatile alkaloid of — Pi cratc, m. p. Nicotiana glauca G-rahajn N. silvestris Speg. and Conas N. glutinosa L. N. taba c;:i L. N. tabacum x N. glauc a N. tabacu m x N. silvest ris The lowest-melting picrate of the group nicotine, nornicotine, and anabasine is that of nornicotine (m. p. 191-2°); honce N. sil vestris (Smith, 37)) as well as the hybrid N. tabacum x IT, sil ve s tri s, contains nornicotine as the chief volatile alkaloid constituent. The allcaloids of N. glauca and of N. glutinosa , forming picrates of closely agreeing melting points, are obviously alike. Smith (36) later showed that the alkaloid of N. glauca is largely anabasine, and this alkaloid has since been reported in K. glutinosa by K. H. Smith and C. R. Smith (unpublished) Spath and Zajic (^6) in 1935 » in the third of a series of papers on tobacco alkaloids, reported on the isolation of 1-nornicotino therein. Starting with a mixture of Kentucky and Virginia tobacro . br.cy prepared a concentrated extract, which was made strongly alkaline c:,nd exhaustively extracted v;ith ether. The ether extract was fractionally d3.s\.illcd, giving a main fraction distilling at 9'^-5° (l nim.) and a highor-boiling fraction. The ether solution of the main fraction was fractionally' ex- tracted with a saturated NaCl solution containing a small quantity of HCl. Each fraction \\ras made alkaline and steam-distilled under vacxium at low temperature until all the nicotine was expelled. The alkaloid rocoverod from the residue v/as converted into picrate (m. p. lSU-8°) , and the base, still n«t pure, was recovered and distilled (l tun.). There was thus obtained an almost colorless liquid hfiving a specific rotation [alpha]§^= -39.7°. This crude nornicotine vras purified by crystallization as the perchlorate from nethanol-ether solution in the form of white crystals. The free base recovered fx-om the perchlorate had, after dis- tillation at 1 i.-ir.i., a specific rotation of [alphr'.i]p= -8S.8° (the density calculated therefrom is d§3= I.070). Analysis for carbon and hydrogen' agreed with the composition CcjH,^"^^' . The picrate melted at 191-2°, and the melting point of a mixture of this picrate with ty' picrate of the Duboisia base (38), which was a mixture of d- and dl-l' lotine, showed no depression. The i-^iornicotinc v'as iiiPthylated with fon.ialdehyde and formic acid into a "base vrh-ich agr^^ed in properties with those of 1- nicotine, as shovm hy optical rotation and hy the nelting points of the picrate, trinitro-n-cresolate, and picrolonate (223-U°, 207-6°, 219°, resp.) . The dimethiodide of this base also agreed in optical rotation and n. p. v;ith that of 1-nicotine. Spathand Zajic vere accordine;ly the first to isolate l-nornicotine in pure forr., having the specific rota- tion of -SS.8°. Hicks and LeMessurier (18) in 1935 investigated the alkaloid of the Australian plant Puboisia hopMOodii . a plant used by natives to catch snas, "by poisoning vraterholes, and also che^^red on occasion by the natives vhen real "pituri" was unobtainable. "Pituri", " which is plant material chewed by the natives, was found to be a variable product; nornally it consists of the leaves of at least t'-ro species of N icotiana , viz, N. excelsior (Black) Black and N. gossei Domin (but not N. s uaveolens Lehn.l . Because of the variability of the product, the lack of botanical identification, and incorrect chemical deduction, confusion existed in the chemica-l literature as to the natvire of the alkaloid of pituri; some vrorkers re;jiboisia hopvroodii . The leaves of this plant are used by the natives of Australia as a chewing material and also as an animal poison. Some chemical ^^rork had already been done by earlier workers on the chewing material, knovm. as "pituri," but with contra- dictory results. The reason for the . confusion in regard to the alkaloid identity of pituri lay, as pointed out by Hicks,' Briicke, and Hueber (17) , in the fact that "^his material vras of a variable nature, not always consisting of I?.-t^^°' )pwoodii , but frequently being admixed with various i./i^ «4fiirV, , , - 8 ~ itiana species and with another si^ecies of Duboisia. The -Dresent investigation on an authentic sample of D. hopv/oodii established the presence of d-nornicotine. From an alcoholic extract of the plant was obtained a main frac- tion of alkaloid distilling at 117° (3-6 mm.), which proved to "be a mixture of d-nornicotir.e and dl-nornicotine. Analysis indicated the formula CoH-,2^'^2' *^^® molecular v^eight, found by the camphor method, was 150.2, compared with lUS . 11 calculated. Other values recorded for this alkaloid are: Density, dJO = 1.0757; refractive index, nJ2.3 = 1.5I19O; specific rotation, [alpha J§^ = +32.3°' "^^e ultra-violet absorption was a maximuiii at 2600 A. U., log e (epsilon) = 3 •15- For nicotine the maxi- mum absorption is at 260U A. U., log e = 3«3T. The dipicrate of this alkaloid melted at 191-2' (without bubble formation); the dipicrolonate melted at 252-3°. The base was methylated with formaldehyde ajid formic acid to nicotine, from vrhich the picrate of m. . p. 22l+° was obtained. The nicotine regenerated from, the picrate had in aqueous solution a specific rotation of [alpha]^ = +^8,3°, hence vras a mixture of the d and dl forms. Pure 1-nicotine vrhen tested under similar conditions (in KOK at low concentration) gave [alpha]^^ = -77-73°. By dividing 77 -73 into '43.3 there results 62 percent as the relative amount of d-nornicotine in the alkaloid and 3S percent as the amount of dl-nornicotine. The approximate specific rotation of pure d-nornicotine was then calculated: +38.3 divided by 0.b2 = +6l.7°. It was realized, however, that this value requires confirmation v/ith the pure d-base. Examination of the methylated base, with respect t^ the methiodide, trinitro-m-cresolate, and picrolonate, gave results consistent for a mixture of d- and dl- nicotins. A further test made on the I>aboisia alkaloid (via benzoylation) proved the absence of nicotine and other tertiary bases. Hicks (15) i^ 193^ further investigated the chemistry of the alkaloid of ^.iboisia hopwoodii . Its methiodide (m. p. 208-9°) ^^ras in agreement with the dimethiodide of nicotine (m. p. 208.5-209.5°)- Identity had previously been shovm by Ehrenstein for the methiodides of 1-nornicotine and nicotine (lO) , The Duboisia alkaloid was dehydrogenated (Pt-asbestos catalyst) according to procedures used by Wibaut and Overhoff (50) and by Ehrenstein (13). The product, b. p. 19^.2° (30 mm.), after re- crystallization from a mixture af ether and petroleum ether (large needles), had the m. p. 100-2°; picrate, m. p. 202-3°. These values agreed with those obtained by Ehrenstein for nornicotyrine, 2-[beta- pyridyl] pyrrole. Hence the alkaloid in Duboisia hopwoodii has the nornicotine structure. Spath, Kicks, and Zajic (39) reported in 1936 that they were able to separate d-nornicotine in practically pure form from the mixed Duboisia base, as the perchlorate. This method had proved successful in isolating pure 1-nornicotine from the tobacco bases (^6), whereby the value for specific rotation, [alpha]^^ = -88.8°, was obtained. For d- nornicotine from I hiboisia was now found [alphajS*-^ = +86.3°, which agreed closely in absolute value with that for 1-nornicotine. The melting points of the picrate, trinitro-m-cresolate,_ and picrolonate, of both forms agreed (l90-l°, 200°, 252°, resp, 1 Spath and Kesztler (U3) in 1937, in their study of totacco bases, investigated the mother liouor remaining after the crystallization of 1-nornicotine diperchlorate. The crude "base recovered from the liquor had a specific rotation of -33-6°. By means of l-6,6'-dinitro-2.2'- diphenic acid there was crystallized from methanol solution a salt of vrhich the regehetated base had a specific rotation of [alpha]^^ = -76.6°, and hence was still largely 1-nornicotine. The "base remaining in solu- tion was then treated with the d-form of the above diphenic acid, whereby was obtained a base leaving [alpha]^. = +^.2°. In order to prepare the racemate this slightly positive base was mixed with the calculated quantity of 1-nornicotine and the optical inactivity of the mixture was confirmed. A derivative of the racemate was made with 2,U-dinitrobenzoyl chloride. The m. p., 159-^0°, was \inchanged on mixture with the same derivative of knovm dl-nornicctine. There was a possibility that the dl-nornicotine so isolated might have been formed by racemization of 1-nornicotine luring chemical in- vestigation. Experiments were made by heating 1-nornicotine for ^8 hours at 100° vrith 10 percent HCl and with 10 percent KOH. The decrease in rotation amounted to only about 2 percent. Since mild conditions were employed throughout the course of treatment of these alkaloids, it could be ass^omed that hardly any racemization occurred, and therefore that dl-nornicotine e:3fists as such in tobacco. In a test of a certain G-erman tobacco the alkaloid found therein ^«ras practically pure 1- nornicotine having [alpha]^*^ = -88.78°. 3y more drastic treatment of 1-nornicotine considerable racemiza- tion v/as induced. Thus, by heating with the calculated truant ity of HoSO^ at 180°, the siDecific rotation fell after 2U hours to -36.7°, and after l^U hours to -i2.6°. ICovalsnko (2l) in 1937 reported a study of the alkaloids of N. rusbyi Britt. and Husby and H. silvestris Speg. and Comes. These plants yielded an alkaloid, or rlkaloids, the picrate of vrhich had the m. p. 178-8^'^. No alkaloid, other than ixicotine, was definitely identified, but i% was established that another steam- volatile alkaloid was present, v;hich formed an insoluble' picrate. It had the character of a secondary amine. {The chief alkaloid in N. silvestris was shovm by Smith (37) to be nornicctine.) Smith (37) in 1937 reported finding 1-nornicotine in ITicotlana silvestris , grown in Virginia, in an amount equal to about 95 percent of the total alkaloids, vmich latter amounted to about 1 percent of the material examined. Associated with the nornicotine vras a small quantity of nicotine, vhich was separated by steam-distillation through a frac- tionating column. The nicotine was identified by its picrate (m. p. 22U°, cor.) and by optical rotation. The base recovered from the residue by ether extraction ha.d the following properties, ^-'hich identi- fied it as nearly pure 1-nornicotine: Sp. gr. 1.07; [alpi^a]^ = -80.0°; picrate, m. p. 191-2° (cor.); b. p. 270-1°. Por comparison, some nor- nicotine \^ras made from nicotine by KI"-!n0^ oxidation (U5) . The picrates agreed in m. el ting, point . The nornicotine from IT. silvestri s was methylated v.rith formaldehyde and formic acid C+S) to nicotine, the picrate of which hc^d the proper melting point (22U°) . Smith also established the prol\able absence of any appreciable quantity of anabasine .^ i.. ^ -lo- in the nicotin.e-free portion of the N. silvestris alkaloid. Zostoff and 3ara;:.a (20) in 1939 described the results of certain breeding expr-riments of tobacco. Under the direction of A. A. Shmuck, the nature of the plants vras determined in part by the difference be- tween tota^ and volatile alkaloids, and by the m. p. of the picrate. The p?rcentage of total alkaloid >/as determined by Keller's method, and the volatile alkaloid (which was chiefly nicotine) by Bertrand's method. The nonvolatile alkaloid group could be determined by difference. These differences for most cases of N. tabacu m were smal;., indicating nearly pure nicotine tj'pes, whereas in IT. silvestris (one of the ancestors of "E. tabacum ) they were considerable. Hence N. silvestris , according to Shmuck, contains a large percentage of nornicotine . ( Smith (37) in 1937 shovfsd that the alkaloid in this species is almost entirely 1-nornicotine.) Hicks (l6) in 19^0 discussed reasons for the confusion existing over the nature of the alkaloid of Duboisia hopwoodii . He pointed out that earlier workers had probably unknowingly worked on a mixture of D. hopwoodii and ITico tiana excelsior and had therefore found nicotine, whereas in fact the alkaloid cf D. hopv/oodii is nornicotine. Mark^'^ood (2b, 27) in 19^0 discovered that a certain strain of ordinary tobacco, N, tabacu m , grovm in Maryland, contained a high per- centage of nornicotine. It ^ras estimated that approximately 95 percent of the total alkaloid (the latter equal to about 0.73 percent of the lea.f) was nornicotine and the remaining 5 percent was nicotine. The melting point of the picrate of the unsepct-rated alkaloid fraction was 187-5°, which vras indicative of nearly pure nornicotine. After removal of nicotine, the picrate melted at ISS. 5-190°. The base was methylated vrith fornaldehyde and formic acid, forming nicotine, which was identified b.y the melting point of its picrate. The tobacco r-iaterial examined here vras a low-nicotine type. Sub- sequent unpublished work indicates an association of nornicotine and low- nicotir.e typos. This is in agreement v;ith the opinion of Zoenig, cited by Wenusch (---7) . It is likely that other strains or types of tobacco will also be found to harbor appreciable proportions of nornicotine. A method for readil;/ recognizing a nornicotine type of tobacco has been pre- liminarily worked out by the writer and awaits further confirmation before publication. Synthesis Pictot and Crepieux (29) in 1895 were the first to synthesize nornic- otyrine, v-hich is a dehydrogenated nornicotine. By distilling a mixture of beta-aminopyridine and mucic ncid the compound N-(beta-pyridyl)pyrrole was formed. This compound underwent rearrangement when heated to a low red heat, forming a lovr-melting compound (m. p. 72°), a C-(beta-pyridyl)- pyrrole, which was regarded as. alpha-(beta-pyridyl)pyrrole(nornicotyrine) . The monopicrate, m. p. 182°; chloroplatinate (CQH2N2-HCl)2-PtCli^-2H20, de- compooing at 150°; a mercury compound, m. p. 175-9°; and the methiodide, m. p. I7O-I', wore described. Chichibabin and Bylinkin (6) in 1923 preparedMa C-(alpha-pyridyl) - _^^.— ' - 11 - pyrrole, starting with alpha-aminopyridine and mucic acid, which were reacted in the presence of AloO-, as a contact substance for splitting out H2O. By passing the N-(alpna-pyr idyl) pyrrole through a slightly glowing tube they effected rearrangement into an isomeric C-(alpha- pyr idyl) pyrrole, which they identified as alpha-(alpha'-pyridyl)pyrrole (alpha-nornicotyrine) , m. p. 87-8°. Wihiiut and Dingemanse (U9) in 1923 follo\<;ed along the line des- cribed by Pictet and Crepieux (2g) but started with alpha-aminopyridine. The product obtained by reaction with nucic acid, and subsequent thermal rearrangement of the N-(alpha-pyridyl)pyrrole, was a mixture of two. isomeric C-(alpha-pyridyl) pyrroles; the main product load the m. p. 90° j while the other isomer had the m. p. 132°. One of these compounds was alpha-nornicotyrine, but vrhich one was not then determined. The compound of 90° in. p. was identical with the pyrrole (m. p. 87-8°) reported by Chichibabin and Bylinkin (6). Wibaut (^8) in 1926 established the structure of the two isomeric C-(alpha-pyridyl)pyrroles prei'lously prepared by Wibaut and Dingemanse (^•9) . By the reaction of ethyl pioolylacetate, chloroacetaldehyde, and WR-, vras obtained a C-(alpha-p'r idyl) pyrrole vrhich could ha.ve only the alpha-alpha structure. This pyrrole, m. p. 37.5-?8.2°, was identical with the pyrrole of S0° m. p. of Wibaut and Dingemanse, and hence the latter compound was alpha-nornicotyrine (alpha.-(alpha'-pyridyl)pyrrole) . The other pyrrole (m. p. 132°) ifas therefore beta,-(alpha'-pyridyl)pyrrole. M. and M. Polonovski (31) in 1927 described a general method for dealkylating tertiary amines to secondary amines, chief amoung such being the tropine alkaloids. The method was then extended to include nicotine, whereby nornicotine vras claimed to be formed (32, 33) • ^^e method con- sisted in treating nicotine oxide (the "oxynicotine" of Pinner and Wolffenstein, Ber. 2'4, 6l-7, I891) with either acetic or benzoic an- hydrides to form the corresponding acyl derivative, vrhich was then saponified, preferably with alcoholic KOH, to nornicotine. The inter- mediates, acetyl-nornicotine and benzoyl-nornicotine, were thick oils. ITornicotine, best purified as the chloroaurate, ^-^as an oil, very soluble in v/ater, from vrhich it vras separated by strong alkali, and was readily extracted by ether. The freshly distilled base, b. p. 150-155° ^* 30 ™^«: was colorless, but rapidly darkened and resinified in air; it ivas difficultly volatile vrith steam, of an odor recalling nicotine. It had the specific rotation, [alpha] = -20° (C = 3-2, in methanol). They prepared the dipicrate, m. p. 135°; chloroaurate, CqH-| 2^^2*'^^^^ '^^^■'■'^' m. p. 210-2°; nitroso derivative, an oil extractable vdth ether; and an oily phenyl isocyauate derivative. Prom later, more trustworthy vrork, it is seen that the nornicotine obtained here vras at best very impure. Yon Braun and Weissbach (5) in 1930 confirmed the inadeauacy of the Polonovski procedure, and proceeded along a similar line vrith better results. They reacted nicotine vrith benzoic or with hydrocinnamic acids (the latter vras preferable), thus obtaining the acyl derivative, which was then saponified to nornicotine. A secondary reaction in the acyla- tion resulted in the opening of the pyrrolidine ring with the formation of a metanicotine derivative. By treatment of the crude reaction product - 12^ with KBr a separation was feffeiJted, and at the same time the hydro- cinnamoyl-nornicotine was hj'dl-dlyted to nornicotine, which wfe.s re- moved in pure condition with ether i The yield was about 20 percent, "based on hydrocinnamic acid, hut less on the nicotine, vrhich was used in excess. The nornicotine obtained had the follov/ing properties: B. p., 266-7*' at atmospheric pressure; 139-^° at 12 mm. It was colorless, stable in air (no darkening or resinifying as with the Polonovski product), miscible with water, strongly basic, of piperidine-like odor. Density, dJS = l.O^U. Specific rotation, [alpha] = -5-5°, but this value was believed to be lower than the maximum rotation because of partial racemization. The picrate was obtained fairly pure by re- crystallization from alcohol; m. p. 188-90°. Purer than the picrate was the finely crystalline picrolonate, from alcohol; m. p. 239-Uo° (sharp). The hj-drochloride could be obtained only as an oil. The chloroplatinate was obtained as small, dark-red crystals, darkening at 270° and decomposing at 2%* . The chloroaurate was obtained as yellow crystals, m. p. 217°. Nitroso-nornicotine was readily formed by reaction of the base with ITaN02 in HCl solution; it was a yellow, viscous oil of b . p. 190-2° at 0.5 mm., miscible with water but separated therefrom by saturation with KoGO-, and extracting v;ith ether, or better, methylene chloride. The picrate, HCl salt, and Au salt were oily. The Pt salt formed fine crystals of m. p. 190°. The mononethiodide was well crystallized, m. p. lUU°. The nitroso derivative was converted into nornicotine by treatment with excess of strong HCl. By nitriting a mixture of nicotine and nornicotine a separation of these tWo bases can be effected, thus: The product is nitrited, then fractionated, whereby the lower-boiling unchanged nicotine is separated, and the nitroso-nornicotine is converted as above. [Such conversion and regenera- tion of nornicotine, however, probably results in partial racemization.] Nornicotine readily formed an acetyl derivative with acetic an- hydride. This derivative was a viscous oil; b. p. 2l2-U° at 12 mm.; specific rotation, [alpha]^*^ = -3.2U°.(in benzene). It formed a picrate, m. p. 151°; an oily Au salt; a Pt salt which decomposed at 2^5°; and a methiodide, colorless needles, m. p. 201°. Nornicotine formed a colorless, crystalline carbamide with cyanic acid, which was nornicotinyl carbamide, C H ON , m. p. l6U-6°. Its Pt salt, small red crystals, darkened at 250^ and decomposed at 270°. The picrate was oily. Nornicotine also ij'ormed a colorless, crystalline derivative with phenyl isothiocyanate, of composition C-igH-iYN^S and m. p. 171°. By the action of ethyl iodide on nornicotine, N-ethyl-nornicotine was made, of b. p. 127-8° at 12 mm. The HCl salt was a hygroscopic solid; the Au salt, yellow crystals which decomposed at 203®; the picrate, m. p. 17^6°. By sirailar treatment of nornicotine with allyl bromide was formed N-allyl-nornicotine, a colorless liquid, b. p. 136-7° at 12mra. It formed a picrate, m. p. 180-2°; a Au salt, decompos- ing at 1^5-8°; a Pt salt, orange crystals, darkening at 230° and de- composing at 255°. [ - 13 - Spath, Marion, and Zajic (U5) in 1936 effected the demethylation of nicotine into nornicotine in tv;o ways. A. By treatment of nicotine with KMnO^ a 0° in aqueous solution a partial demethylation occurred. The crude mixed basic product vas dissolved in ether and fractionally extracted with 0.1 N HCl saturated with NaCl, whereby the nornicotine was removed with only a small admixture of nicotine. The nicotine was then expelled "by vacuum distillation with water. The crude product was purified "by repeated recrystallization of the picrate, which was finally obtained pure with a melting point of 191°. The picrate was decomposed with HCl, the free base recovered and distilled. There was thus obtained, from 6.0 g. of nicotine, O.Ul g. of nornicotine. Specific rotation, [alpha]^*-* 5= -76.1"; by crystallization as the perchlorate the rotation was increased to [alpha]^^ =* -S3. 2°. [Calculates to a density, d^O = 1.07O.] The picrolonate, m. p. 252°, and the trinitro-m-cresolate, m. p. 200° were made, B. The second method employed by these workers for demeth^rlating nicotine consisted in treatment with silver oxide. This reaction dates back to Blau (Ber. 27, 2535-9, IS9U) , v;ho thereby prepared nicotyrine, a dehydrogenation product of nicotine, but did not report the formation of nornicotine. The crude reaction product was fractionated as before. From ho g. of nicotine there was obtained 3 .9 S- 0^ nornicotine di- picrate, m. p. 190-191°. Before conversion to picrate the base had a specific rotation of -H0°; after purification via the picrate it showed [alpha]20 = -SS.8° (dgC = 1.07O) .' Craig (7) in 1933 synthesized nornicotine, and from it nicotine, by a series of aggregating steps starting with pyridine. Hence this method, while lengthy, represents more traly a synthesis than does the demethylation of nicotine. Pyridine vas sulfonated to sodium beta- pyridine sulfonate and the latter converted with NaCU to nicotinic acid nitrile. The nitrile was then reacted with the Grignard reagent made from gamma-bromo-propyl ethyl ether, v;hereby was formed beta-p;iTidyl- gamma-ethoxypropyl ketone, which v;as a new compouxi.d. From this ketone was formed the oxime with hydroxylamine . The oxims was reduced to the amine, l-[beta-pyridyl j-1-araino-U-ethoxybutane, which was dealkylated with HBr to the hj/droxy compound. Eing closure to make the pyrrolidine ring followed, and by addition of KOH a basic oil separated from which was obtained an oil distilling at 139-lUo° (l2 mm.). The properties of this oil agreed throughout with those reported by von Braun and Weissbach (5) for nornicotine, and similarly the picrate and phenyl thiourea com- pounds were in agreement. Methylation with CH-7I to racemic nicotine followed. The author noted that nornicotine is a stronger base than nicotine. The foregoing process represented a complete new synthesis from pyridine of the two bases in racemic form. Craig (8) in 193^ "^7 ^ similar procedure prepared so-called alpha- nornicotine and alpha-nicotine, in which linkage to the pyridine ring is in the alpha position instead of the beta position. The alpha-no r nicotine was described as a rather pleasant-smelling oil, soluble in water and in organic solvents in all proportions. The picrate melted at l66°. A phenyl thiourea derivative was made but could not be obtained pure. Spath and Kesztler (Ul) in 1936 resolved synthetic dl-nprnicotine prepared by the method of Craig (S) into the two optical antipodes. Whereas Pictet and Rctschy (Ber. 37, 1225-35, 190U) were able to resolve - lu - Al-nicotine "by means of tartaric acid, this acid proved unsuita"ble for nornicotine, and resort was had successfully to the optically active acid, 5,6'-dinitro-2,2'-diphenic acid, which, gave vrell-crystallized salts with the several to"bacco bases. The preparation of this acid and its resolution into d- and l-forms through the quinine so.lt v-ere dis- cussed. The dl-nornic«tine was first treated in methanol solution v/ith 1-6, 6'-dinitro-2,2'-diphenic acid; crystals of 1-nornico l.ino- !■• dinitrodiphenate were ohtained. The "base .recovered frOiH 'Mr-, litter "by decomposition with HCl first had a rotation, [alphaji^- = -Ua. ;; /; after purification through the perchlorato it had [alph^]^' = -S'i.F-^\ The mother liquor, on treatment with the d-diphenic acid, gave cy^-t iJa of d-nornicotine-d-dinitrodiphenate, the recovered "base of whici. f : ;t liad a rotation, [alpha]^'^ = +Ug.O®, and after purification as the porcilorate had [ alpha] J^ = +86.08'. For 1-nornicotine diperchlorate so prepared, CQH>j_i|0gN2Cl2> ^* p. 1S3-6'*, [alphali^ = +13.6° (in Wciter; c = 5.28). Tor the diperchlorate of natural 1-nornicotine, [alpha]^^ = +13. U° (in v;ater, c = 5.23). For d-nornicotine diperchlorate, [alpha]^^' = -12.98° (in water, c = 5.2h) . Spath and Kainrath (Uo) in 1938, in their work on the simplifica- tion of the classical Pictet nicotine synthesis, prepared the ccuxound l-( 3 '-pyridyl) pyrrole from 3-'^-3iiriOpjT*idine and mucic acid. This pyrrole by thermal treatment at 700° rearranged into two isomeric pyrroles, of which one was 2-(3'-pyridyl)pyrrole (nornicotyrine) , m. p. 97° (picrate, m. p. 200-2°); the Other isomer vras 3-( 3 '-pyridyl) pyrrole. Separation was effected by repeated crystallization of the free bases and their picrates, NornicotjTrine was reduced wi'bh hydrogen and Pri-sponge as catalyst to dl-nornicotine (dipicrate, m. p. 19'^°) . The crude hydrd- genation product vras also methylated with formalder^'de and formic acid to dl-nicotine. Lions and Ritchie (22) in 19U0 published a new synthesis of nor- nicotyrine, 2-( 3 '-pyridyl) pyrrole, in order definitely to confirm its constitution. It was synthesized from ethyl nicotinylac state, NC5HI1COCH2CO2C2H5, ethoxy ethyl enedichl or ide, CH2ClCHC10C2Hr,^ and strong NH3. The purified product, nornicotyrine, vras isolated in the form of needles, m. p. 92-9°, which gave a blue fluorescence in a mi.-.ture of benzene and petroleum ether (picrate, m. p. 203-^° (d.)), 1'l.is. t;/pe of synthesis, involving NHt, represents a departure from most fornior modes but is similar to the sjTithesis of alpha-nornicotyrine, employed by Wibaut (U8) in I926. Analytical Determination Qualitative tests for nornicotine are based upon such factors as the appearance and melting point of salts, e. g. , picrate 191-2°, 2,!|,6 trinitro-m-cresolate 200°, picrolonate 252°, urea l67-70°, phenyl thiourea 176-7°, and chloroaurate 217°. Methylation to nicotine, .with identification of the latter, is valuable evidence of nornicotine. - 15 - The optical rotation and other physical properties are also valuable means of identification. The quantitative determination of nornicotine has not been fully iiyestigated. It may be said, however, that any methods applicable to nicotine (with due regard to the difference in volatility with steam) are also applicable to nornicotine. The chief problem most likely to be encountered is the quantitative separation of nornicotine and nicotine as they occur in tobacco. Von Braun and Veissbach (5) in 1930 pointed out that a separation of nornicotine from nicotine could be effected by forming the nitroso derivative of nornicotine with IQTO2 in HCl solution; nicotine was not changed thereby. They then fractionally distilled the isolated bases and obtained nipotine as the lower-boiling fraction. [This method may be satisfactory for a quantitative determination of nornicotine, but it is open to objection in the preparation of 1-nornicotine because sub- sequent regeneration of nornicotine from the nitroso compound by means of strong HCl may result in racemization.] P. Zoenig (19) in 193^ observed that the distillates of certain tobaccos gave picrates of melting point departing considerably from that for pure nicotine (218-222.5°). These picrates melted at 2lU°, 205°, 193°, and even 173°; "tiie depression in melting point was attributed to foreign bodies, of which the chief one v;as nornicotine. He described a method for quantitatively separating these bases, by virtue of their difference in basicity and in volatility v/ith steam, A distillation from MgO solution yielded only the nicotine in the distillate, x^hile the UaCH distillation yielded both alkaloids. This was explained by the fact that nornicotine, being the stronger base, was less readily liberated from its salts, and also that it was less volatile with steam. The bases in the respective distillates were precipitated with picric acid, and the picric acid content of the picrates \^s determined by titration X'^rith NaOH. [Note: This separation is only approximate, and it favors a high value for nicotine, as nornicotine is volatile enough to distil over partially from MgO solution,] Pharmacologic'- Dingemanse, Laqueur, and Wibaut (9) in 192b reported on the pharmacology of certain pyridine and pyrrole derivatives. Anong them was olpha-nornicotyrine ( alpha- ( alpha '-pyr idyl ) pyrro 1 e) , m. p. 90°« ^ frog injected with 1 cc. of a 1-percent solution of alpha-nornicotyrine showed symptoms of paralysis. As an anesthetic this compound v;as about twice as active as novocaine. The general conclusion reached from this and other tests was that the alpha-pyridine compounds have about the same degree of physiological activity as the beta-pyridine compounds. (This conclusion, hov/ever, is not borne out by the tests of other in- vestigators.) The first information concerning the toxicity of nornicotine comes from A. Be^gT^rall, whose report of pharmacological tests was cited by Ehrenstein (13) r,n 1931 • I* was the latter' s nornicotine, isolated from tobacco, which •Vrei.s tested, and this it should be noted v;as not -Im- pure 1-nornicotine tut a mixture of the 1- and dl-forms (approximately 20 percent 1- and 20 percent dl-nornicotine) . Tests on the contraction of frog muscle showed nornicotine to have only one-tenth the activity of nicotine. Blood pressure tests on cats (injection in the Vena j ugular is ) shovred that nornicotine, like nicotine, causes a rise in arterial pressui'e which is accompanied hy irregular heart action, but the effect was weaker than that produced "by nicotine. It \>ras difficult to give numerical evaluation to tests of this kind, as repeated injections diminished the effects. Nor- nicotyrine (S-Cheta-pyridyll-pyrrole) , on the other hand, caused a lowering of "blood pressure, hut the action was relatively weak. Macht and Davis (23) in 193U reported toxicity tests on the following compounds, which '.^rere prepared hy L. C. Craig: l-beta-nicotine dl-h eta-nicotine dl-heta-nornicotine . dl-alpha-nicotine dl-alpha-nornicot ine (l-"beta-Nornicotine, the form naturally occurring in tobacco, vra.s not included.) The tests embraced grovrth studies on seedlings of Luoinus albus L., and mortality studies on tadpoles, goldfish, viater turtles, land turtles, white mice, white rats, guinea pigs, and cats. All five compounds were toxic, but the order of toxicity varied with the different test objects. In nearly all cases 1-beta-nicotine (natural nicotine) vras the most toxic. The beta compounds without ex- ception v;ere more toxic than the alpha. In general dl-bota-nornicotine was more toxic than dl-beta-nicotine, but there were exceptions. As between dl-alpha-nicotine and dl-alpha-nornicot ine, the order of toxicity was about equally divided, A typical picture of toxicity, showing the effect of intravenous injection of cats, in terms of mg. of compound per kg. of cat for lethal dose, is given in the following set of values (the order of compounds is that given above) J I.3, 2.0, 0.9, 6.1, 13.I. Macht and Davis (2U) in 1935 made a special report on the toxicity of the several compounds tested previously (23). The test here was con- fined to inhibition of root growth of seedlings of Lupinus albus . The data and conclusions of the previous article were substantiated. In addition, new data were given on the effect of combinations of those bases. The results shovred that certain combinations gave simple additive effects, agreeing with the calculated summation, while others produced a synergistic (greater than the calculated) effect, and still other com- binations were antagonistic. Hicks and LeMessurier (l8) in 1935 investigated the toxicological behavior of the alkaloid of Duboisia hopwoodii . whiph was nornicotine, roughly in 1:1 ratio of the d- and dl-forms. The ^, 1. d. for rats (peritoneal injection) was O.OO17 g.; the m. 1. d(.^^ nicotine was - 17 - 0.00^5 g.; hence the 3Xi"boisia alkaloid was about 2-l/2 tines as toxic as nicotine. The action on the isolated perfused mammalian heart was similar to that of nicotine. Intravenous injection into the intact animal (rabbit) caused a rise of blood pressxire similar to that given by adrenaline, followed by paralysis of the vatgus. This effect was similar to that produced by stimulation of the splanchnic ganglia by nicotine. The action on isolated frog's gastrocnemius preparation was similar to that of nicotine. It was noted that the symptoms of poisoning in the rat were distinct from thoise produced by nicotine, although death in -both cases \^s due to respiratory failure. The Duboisia plant is also known to be very trxic to camels, as one mouth- ful of the bush is fatal to these animals. Hicks, Brucke, and. Hueber (17) in 1935 reported more completely on the pharmacology of d-nornicotine, which was isolated- from Duboisia hopwoodii . Brood-pressure experiments on cats were conducted, and the action on peripheral ganglia was studied, both with reference to heart ganglia (isolated frog heart) and to the ganglion cervical e supremum (cat) . The action on isolated frog muscle ( muse , rectus abdominis ) and on the posterior extremities of a dog were also studied. The con- clusions reached were that the action of d-nornicotine on blood pressure, respiration, and vasomotor centers, as well as on peripheral vagal and sympathetic ganglia and on the heart, is not different from that of nicotine. The isolated frog muscle was somewhat more sensitive to d- nornicotine than to nicotine, but the difference was only slight. Richardson, Craig, and Hansberry (3^) in 193^ summarized the toxic action of a group of N-heterocyclic compounds upon the bean aphid, Aphis rumicis L. The compounds were applied in 0.25 percent sodium oleate solution. The concentrations required for 50 ^^^ 100 percent mortalities "of the insect were: 50 percent 100 percent Compound net mortality net mortality mg. per 100 cc. mg. per 100 cc . 1-beta-nicotine ' . 1+9 1,185 dl-beta-nornicotine 1+5 1+90 dl-alpha-nicotine 1,^96 10,960 dl-alpha-nornicotine . 1,51^ lOjUyO dl-beta-nicotine 96 1,259 anabasine 5 1^^ The results show the marked superiority of the beta compounds. Anabasine stands out as the most toxic aphicide. There v;as no great difference between the comparable methyl- and nor-forms. Natural nicotine was about twice as toxic as its racemic isomer. Although 1-beta-nornicotine, the alkaloid occurring in tobacco, v;as not in- cluded in this study, the racemic form of beta-nornicotine was shown to be somewhat more toxic than natural nicotine, and hence 1-beta- nornicotine quite likely would have a toxicity of the same order. It should be borne in mind that the results reported here apply only to the bean aphid and that the degree and order of toxicity can be different for other insects. This work represents the first insecticide investi- gation reported on nornicotine. - 18 - Wenusch (hj) in I936 pu'blished an interesting account of the toxicity of l-nornicotine as it relates to the smoking' of totacco . Cigarettes made of a nornicotine to'bacco were smoked by' intermittent puffs, and the smoke was caught in dilute sulfuric acid. The strongly alkaline liquid was exhaustively steam-distilled, and the picriate of the alkaloid was formed in the distillate. Since nornicotine dipicrate is more soluble in water and in alcohol than is nicotine' dipicrate, it was possible to effect a separation of these two "bases by fractional crystallization of the picrates. Compared with the amo\int of nornicotine in the original tobacco, the amount in the main Smoke stream was quite small; about 25 percent of nicotine passes into the smoke by inter- mittent smoking but the corresponding percentage of nornicotine is much less. In the soluble picrate fraction, beside one of m. p. 217-B**, there was obtained a picrate that blackened at 150°, sublimed in drape, melted at 192-^*, and when made alkaline smelled strongly like myosmine (mousy odor) but was not myosmine* A picrate of the same properties was prepared from nornicotine by KMnOij. oxidation,' Since this picrate could not be obtained directly from tobacco, it must bvro its origin to air-oxidation of nornicotine ftn coking. It appeared to be much less toxic than nicotine. l-Nornicotihe was physiologically less active than l-nicotlne, as revealed by tests on the contraction cf leech muscle. A solution of 1:300,000 of 1-nicotine produced approximately the same degree of contraction as a 1:60,000 solution of l-nornicotine, hence the activity was roughly one-fifth. The conclusion reached was that the presence of l-nornicotine in tobacco is toxicologically of minor importance since it is less toxic than nicotine and passes over into the smoke to a much less degree than nicotine. Hansberry and Norton (lU) in 19^0 reported on aphicidal (Aphis rvunicis ) tests vdth 1- and d-nicotines and 1-, d-, and dl-nornicotines. The 1-nicotine was obtained pure by the method of Ratz (Monatgh. 2d, I2U1-52, 1905); [alpha] =-168.90°. The d-nicotine was crystallized as the 1-tartrate from racemized nicotine, prepared by heating natural nicotine with H2SOI1. The l-nornicotine was isolated from N. silvestris grown at Ithaca, II. Y.; the plant contained approximately l.U percent crude alkaloids, of which 57 percent was nicotine and U3 percent nor- nicotine. The purified l-nornicotine had a specific rotation, [alpha] = -82°. The d-nornicotine was the base prepared from Daboisia hopwoodii and was furnished by G. S. Hicks of Australia. The dl- nornicotine was prepared from nicotine by the method of Iron Braun and Weissbach (5); the rotation was not determined; the picrate melted at 191-191.5°- The compounds were applied in O.25 percent sodium oleate solu- tion. The results are shown in the following table: I -'19 - Mean percent mortality of Aphis riunicis L Material Concentrat ions used, percent 0.00'^ 8 0.02 32 - 0.05 80 0.2 o.u 2.0 1-nicotine 87 100 d-nicotine 28 )45 90 100 1-nornicotine 16 63 98 100 d-nornicotine 16 i+s 65 100 dl-nornicotine 13 37 90 . 100 It is apparent that d-nicotine was substantially less toxic • than any. of the other alkaloids. All the nornicotines were more toxic than natural (l-) nicotine. 1-Nornicotine v;as doubtfully more toxic than the d- or dl-forms. No pronounced difference existed "be- tvreen the d- and 1- forms of nornicotine. The data indicate that ex- tracts of Nicotiana silvestris and Duboisia hopwoodii may be better insecticides than nicotine, toward some insects. The results of the tests with aphids indicate that nornicotine should be tested as an insecticide against other species. It may also have other uses, such as a vermifuge for poultry and other animals, especially if the nornicotine, when used for this purpose, proves to be less toxic to the host than is nicotine. Patents U. S. patent 2,219,287, dated October 29, 19U0, to Robert B. Arnold (U) , assignor to Tobacco By-Products and Chemical Corporation, specifies the group anabasine, nornicotine, and nicotine in combina- tion with a basG-exchange polysilicate, as a parasiticidal spray com- position. Reviews and Popular Accounts Marion (25) in 193^ presented a review of the tobacco alka- loids, which included a discussion of nornicotine. Spath and Kuffner (UU) in 1939 presented a comprehensive review on the entire subject of tobacco alkaloids, of ^yhich nornicotine is one, Popular accounts of Markwood's discovery of nornicotine in Mary- land tobacco appeared in Science Nevrs Letter (3), Science Digest (2), Modern Medicine (l) , and in newspapers, such as the New York Times (Sept. S, 19U0) and Buffalo Evening News (Oct. 16, 19^0). Summary Nornicotine is a colorless liquid alkaloid which occurs in the Nicotiana species tabacum L. a.nd silvestris Speg. and Comes, and in Duboisia hopwoodii F. Muell. It probably also occurs in other incom- pletely investigated species of Nicotiana . In chemical composition it - 20 - is 2- C3'-pyr idyl) pyrrolidine, Cg^g^Z) and differs from nicotine, to which it is closely related in chemical structure and physiological action, by the presence of an NH instead of an N'CH? group. Nornicotine appears to be more stable than nicotine, has a higher boiling point, and is less volatile with steam. Pharmacological tests indicate that in general it is less active than nicotine toward warm-blooded animals, but that toward insects (as judged by behavior with Aphis rumicis L.) it is equally toxic, perhaps even superior. This conclusion is only provisional, hovrever, as very few insecticidal tests have been made. The prospects for a supply of nornicotine are excellent, since a fairly rich source of it has been found in a domestic tobacco. From the insecticidal point of view it deserves thorough testing by ento- mologists. It may also have other applications, such as a vermifuge for poultry and animals. Literature Cited 1 . ANONYMOUS I9U1. 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