92 JOWETT AND PPMAN : RELATION BETWEEN CHEMICAL VII1.-Relation between Chemical Coristitution arm? Physiological Action in the Tnyeines. By HOOPER ALBERT DICKINSON JOWETT and FRANK LEE PY~IAN. IN a previous communication (Trans., 1906, 89, 357) it was shown by one of us, in conjunction with Mr. Hann, as the result of the physiological examination of a number of new tropeines : (1) That the peculiar difference in physiological action between a lactone and its corresponding hydroxy-acid, as exemplified by pilo- carpine and pilocarpic acid, also occurs in the case of a tropeine having a haptophore group similar to that in pilocarpine, namely, terebyl- tropeine, and also in the case of phthalidecarboxyltropeine. (2) That Ladenburg's generalisation, so far as it refers to the necessity for a mydriatic tropeine to contain a benzene nucleus, does not strictly hold since terebyltropeine possesses a distinct mydriatic action.I n order further to elucidate these two points the following tropeine was prepared and physiologically examined : ? /\.GO-- \/'CH(OH)*CH*CO*C,H,,ON I I ' Lactone of o - Cnrboxyphen ylglgceryltropeine. If Ladenburg's generalisation is valid, namely, that a tropeine to possess mydriatic properties must contain an acyl group attached to a benzene nucleus, and an aliphatic hydroxyl in the side-chain containing the carboxyl group, and if the observation that a lactone is much more active physiologically than the corresponding hydroxy-acid applies also in this instance, then the above tropeine should be a very powerful mydriatic, for it fulfils the requirements of Ladenburg's generalisation and is also a lactone.Its corresponding hydroxy-acid would contain two hydroxyl groups in the side-chain bearing the carboxyl, and the lactone of such a compound might naturally be expected to prove very active physiologically. It was found that this tropeine, on heating, readily lost the elements of water, forming isocozcma~.incurbox?/ltr~peilze, /\.co--- ? - /).CO-? \/*CH I t (OH)-CH-CO-C,H,,ON -+ (/CH: C*CO*C,H,,ON ' in a manner similar to the conversion of the lactone of o-carboxy- phenylglyceric acid into isocoumarincarboxylic acid (Bamberger and Kitschelt, Ber., 1892, 25, 896).CONSTITUTION AND PHYSIOLOGICAL ACTION IN THE TROPEINES. 93 This lactone was examined physiologically, and it was also thought to be of interest t o prepare and examine physiologically certain alkyl bromides of these tropeines, as well as those of homatropine.The necessary physiological experiments were conducted in the Wellcome Physiological Research Laboratories by Mr. C. T. Symons, to whom we wish to tender our best t*hanks, and he reports as follows : No effect was observed on instillation of aqueous solutions into the conjunctival sac, but a certain degree of mydriasis mas produced by intramuscular injection ; in this respect, therefore, they mere very much weaker than homatropine or atropine. Experiments were also made t o determine their action on the vagus nerve-endings in the heart, and in this respect also they proved t o be much less active than atropine.With regard to their action as lactones it mas found that, similarly to pilocarpine (compare Marshall, J. Yhysiol., 1904, 31, 153), they lost their action on the vagus nerve-endings in the heart after a molecular proportion of alkali had been added to the base, this change of activity being undoubtedly due to the conversion of the lactone into i t s corresponding hydroxy-acid. With regard to the alkyl derivatives of these tropeines, it was found that distinct differences in activity exist between the hydrobromides on the one hand and their corresponding methobromides on the ot,her. As has teen observed before with other alkaloids, so here, the introduc- tion of a methyl group, forming a quaternary nitrogen base, very much diminishes the action of the substance on nerve centres, and induces a more curare-like action on the motor nerve-endings in voluntary muscle. This is particularly noticeable in a comparison between the hydrobromide and the methobromide of the lactone of o-carboxyphenylglyceryltropeine, and also appears in a less pronounced degree in the case of isocoumarincarboxyltropeine. The alkyl salts of hornatropine were compared with homatropine hydrobromide as regards the mydriatic action produced on instillation OF 0.5 per cent.solutions into the conjunctival sac, and it was found that the pupils of cats’ eyes were dilated more completely and more quickly by the methobromide and methonitrate than by the hydro- bromide, but only very slightly by the ethobromide. The results of this investigation confirm and amplify the conclusions previously arrived a t (Zoc.cit.), and prove that Ladenburg’s generalisa- tion cannot be maintained, since it does not hold good in the case of terebyltropeine, which is mydriatic although not conforming to the generalisation, nor in the case of the lactone of o-carboxyphenyl- glyceryltropeine, which should according to the theory be very active, but does not prove t o be so. The tropeines were slightly mydriatic.94 JOWETT AND P’S’IVIAN : RELATION RETWEEN CHEhIICAL On the other hand, the difference in activity between the lactone and its corresponding hydroxy-acid, first noticed in the case of pilocarpine and pilocarpic acid by Marshall (Zoc. cit.), is shown in all the tropeines examined, and i t seems hardly open to question but that this difference possesses important physiological significance, and further inquiry into the reason of this difference should throw considerable light on the mode of action of these substances. E x P E R I M E N T A L.Lactone of o-Car6oxyphenyZglyceryZtropeine, /\*CO--? ‘0 CH(OH)*~H*CO*C,H,,ON This base was prepared by passing hydrogen chloride through a solution of tropeine neutralised with the lactone of o-carbosyphenyl- glyceric acid, and maintained a t a temperature of 120-125’ for two to three hours (Tauber, D.R.-P. 95853). The resulting dark brown gum was decomposed by ammonia, and the base, which separated in grey crystals, was purified by recrystallisation from absolute alcohol and obtained in rosettes of stout, acicular, colourless crystals which melted a t 172-173’.The base is insoluble in water and moderately soluble in alcohol : 0.2522 gave 0.6029 CO, and 0-1463 H20. C,,H,,O,N requires C = 65.2 ; H = 6.4 per cent. The hydrochloride separated from its aqueous solution, on evapora- tion i n a vacuum over sulphuric acid, as a viscid oil which gradually solidified, forming dense rosettes OF fine, acicular crystals. After recrystallisation from absolute alcohol, it was obtained in imperfect crystals, which melted a t 228-229’ and decoinposed a t 235’. This salt is anhydrous and is very easily soluble in water, but moderately so in absolute alcohol : C = 65.2 ; H = 6.4. 0.12 gave 0.0487 AgCI. C,sH,,O,N,HC1 requires C1= 9.6 per cent. The hydrobyomide separated from absolute alcohol in rosettes of fine, acicular crystals which melted a t 212-213’ ; it is very easily soluble in water and moderately so in absolute alcohol.,The air- dried salt contained 1 molecule of water of crystallisation, which was not entirely lost after five hours’ heating at 150’, and at a higher temperature the substance decomposed : C1= 10.0. 0.2078 air-dried salt gave 0.0906 AgBr. Br = lS.6. 0.1196 ,, ,, ,, ,, 0.0518 AgBr. Br=18.4. ClsH,lO,N,HBr,HzO requires Br = 18.6 per cent.CONSTLTUTION AND PHYSIOLOGICAL ACTION IN THE TROPEINES. 95 The hydriodide crystallised from absolute alcohol in microscopic prisms which melted at 204-205'; it is anhydrous and is very easily soluble in water, but sparingly so in absolute alcohol : 0.1812 gave 0.0916 AgI. 1=27*3. 'l'he nilrate crystallised from absolute alcohol in long, fine needles This salt is anhydrous and is very ClsH2105N,HI requires I = 27.6 per cent.which melted a t 174-175'. easily soluble in water and moderately so in alcohol : 0.0732 gave 0.1470 CO, and 0.0384 H,O. C,,H,,O,N,HNO, requires c! = 54.8 ; H = 5.6 per cent. When this salt is heated for some time a t 130' it decomposes, turning brown and losing water, and the decomposition product yields on recry stallisation from alcohol the nitrate of isocoumarin- cuboxyltropeine melting a t 238'. . 'l'he auricldoride separated from boiling water in stellate clusters of yellow needles which melted at 215-216"; it is anhydrous and is niodemtely soluble in boiling water, sparingly so in alcohol : C = 5 4 4 ; H=5.8. 0.3366 gave 0 0991 Au. C,,H,,O,N,HAuCl, requires Au = 29.1 per cent.Tht) platinicldoride separated from boiling dilute hydrochloric acid in groups of stout, yellow needles which melted and decomposed a t 193-1944 The air-dried salt contains 2 molecules of water of crystallisation which are only expelled a t a temperature of 150'; the anhydrous salt is redder than the hydrated salt : Au = 29.4. 0.2026 air-dried' salt lost 0.0063 H,O. 0.1448 ,, ,, ,, gave 0,0254 Pt. Pt = 17.5. 0.2902 ,, ,, ,, +, 0.0509 Pt. Pt = 17.5. H,O=3*1. (C,,H,,0,N),,MBPtC1,,2H,0 requires H,O = 3.3 ; Pt = 17.6 per cent. The picrate crystallised from hot water in short, yellow needles which melted at 218-220'. The methobroinide was prepared by adding excess of methyl bromide to a solution of the base in absolute alcohol at 0', and allowing to stand for one hour, when it Reparated in small needles.After crystallisation from absolute alcohol it melted a t 257-258' ; this salt is readily soluble i n water and very sparingly so in absolute alcohol : C,,H,,0,N,CH3Br requires Br = 18.8 per cent. 0.17 gave 0.0756 AgEr. Br= 18.9. isoCoumarincarboxyltropeine, 1 .v CIJ : C COO C,H,,ON This base mas prepared by heating the lactone of o-carboxyphenyl- glyceryltropeine to 120-1 25' until no further diminution in weight96 JOWE'lT -4ND PYMAN : RELATION BETWEEN CHEMICAL took place. The product was somewhat discoloured, and mas purified by repeated crystallisation from absolute alcohol ; the pure base formed colourless, glistening leaflets melting at 179-180°, which are only sparingly soluble in water, ether, and cold alcohol : 0*1804 gave 0.4561 CO, and 0.1025 H20.C=69*0; H=6*3. 0.2100 ,, 0.5315 CO, ,, 0.1185 H,O. C -69.0 ; Hs6.3. Cl,HI,O,N requires C = 69.0 ; H = 6.1 per cent. The Itydrocldoricle sepzrnted from its solution in absolute alcohol in tufts of slender needles ; it melted and decomposed a t 287--38S0, and is easily soluble in water, but sparingly so in boiling absolute alcohol. 0.2204 gave 0.0910 AgC1. C1= 10.2. C18H,90,N,HCI requires C1= 10.1 per cent. The hydrobromide, which separated from its solution in absolute alcohol in long, fine, matted needles, melted and decomposed at 252-2533; this salt is 'easily soluble in water and moderately so in absolute alcohol, and contains one-half a molecular proportion of water of crystallisation : The salt is anhydrous : 0.2811, dried a t looo, lost 0.0071 H,O at 120'.0.1016 ,, ,, 120°, gave 0.0494 AgBr. Br = 20.7. H,O=2*5. (Cl,H,,0,N,HBr)2,H,0 requires H,O = 2.2 per cent. C,,H,,O,N,HBr requires Br = 20.3 per cent. The hydq-iodide formed glistening scales which melted at 280-2W ; it is sparingly soluble in water and absolute alcohol, and contains one molecule of water of crystallisation : 0,3616 air-dried salt lost 0.0139 H,O a t 150". 0.2264 dried a t 150" gave 0*1208 AgI. H20=3%. I = 28.8. Cl,H,,04N,HI,H,0 requires H,O = 3.9 per cent. c!l, H15)04N,H1 9 , I = 28.8. The nityate was precipitated as a flocculent mass of glistening needles on adding dilute nitric acid to the solution of the base in absolute alcohol; the salt melted and decomposed at 228--229O, and is readily soluble in water and sparingly so in absolute alcohol, but insoluble in ether.It contains one half a molecular proportion of water of crystallisation, and after drying at looo : 0.4677 lost 0.0111 H,O a t 120". 0.1759 gave 0.3626 CO, and 0.0908 H20. (C,,H,,07N,),,H,0 requires H20 = 2.3 ; C = 56-1 ; H = 5.5 per cent. The aurichloyide was obtained as a yellow, crystalline precipitate ; on recrystallisation from absolute alcohol it separated in imperfect crystals which melted and decomposed at; 254-256O; the salt is H,O=2*4. C = 56-2 ; H = 5.7. 0.2015 ,, 0.4125 CO, ,, 0.1012 H,O. C=55*8; H=5*6.CONSTITUTION AND PHYSIOJ OG ICAL ACTION IN THE TROPEINES. 97 almost insoluble in water and very sparingly soluble in boiling absolute alcohol ; it is anhydrous : 0.1096 gave 0.0334 Au.C,,H,,O,N,H AuCI, requires AU = 30.2 per cent. The pkatinichloride separated as a flocculent, amorphous precipitate. It was recrystallised from dilute hrdrochloric acid and melted and decomposed at 264-265". The salt is almost insoluble in water and alcohol, and contains 1 molecule of water of crystallisation, which is lost at 120° : AU = 30.5. 0.1802 lost 0.0031 H20. H,O = 1.7. 0.1771, dried a t 120°, gave 0.0329 Pt. Pt = 18.6. (C,,H,,04N)2,H2PtC16,H,0 requires H,O = 1 *7 per cent. (C,,13,,0,N),,H2PtC1, requires Pt = 18.8 per cent, Tho picrate crystallised from strong alcohol in matted, yellow needles, which turned brown at 240°, and melted and decomposed at 2 6 5 O . The methobromide was prepared in the same way as the lactone of o-carboxyphenylglyceryltropeine methobromide. It separated from absolute alcohol, in which it is sparingly soluble, in matted needles ; it is readily soluble in water : 0.1168 gave 0.0542 ApBr. Br = 19.7.Ci8H1904N,CH3Br requires Br = 19.6 per cent. Honzatropine &thobromide, C,,H,,O,N,C,H,Br. This salt was prepared by heating homatropine with excess of ethyl bromide in a sealed glass tube at 100' for one hour, and mas purified by crystallisation from absolute alcohol ; it melted at 209-210°, and is readily soluble in water and moderately so in absolute alcohol, but insoluble in ether ; it is anhydrous : 0.2138 gave 0.1028 AgBr. Br = 20-5. C,,H2,03N,C,H,Br requires Br = 20.8 per cent. Homatropine methobromide, C,,H210,N,CH3Br, has already been prepared by Merck (D.R.-Y.145996), who gives the melting point 180-1819 On repeated recrystallisation from absolute alcohol, we have been able t o obtain the salt in a state of greater purity. The pure salt melts at 192-196", is very readily soluble in water, and moderately so in absolute alcohol; it is anhydrous : 0.2614 gave 0.1296 AgBr. Br=21.1. Cl,H2,O,N,CH3Br requires Br = 21.6 per cent. Honta t rop ine Method'phate, (Cl6H 2 1 OSN ) 23 ( CH3)2S04. This salt was prepared by heatiag an alcoholic solution of homatro- pine with dimethyl sulphate in a sealed glass tube st 100' for two VOL. XCL. H98 BENTLEY AND WEIZMANN : hours. On concentrating the alcoholic solution in a vacuous desic- cator over sulphuric acid, a syrup was obtained from which a small quantity of crystals separated.After recrystallisation from absolute alcohol, the salt melted at 172-1'74"; it is readily soluble in water and moderately so in absolute alcohol : S= 4.9. !C,gH2,0,N),,(CH~),S0, requires S = 4.7 per cent. Hornatropine Methowitrate, C,,H,,0,N,CH3*N0,. This salt mas prepared by the action of silver nitrate on an aqueous solution of homatropine methobromide. The silver bromide was removed by filtration, and the filtrate evaporated in a vacuum, first on the water-bath, then in a desiccator over sulphuric acid. It separated as a viscid oil, which gradually solidified, and after crystallisation from absolute alcohol melted a t 134-135' : 0.1582 gave 0.0563 BaSO,. 0,1875 gave 0.3963 CO, and 0.1 183 H,O. C = 57.6 ; I3 = 7.0. C,,H2,0,N,CH;NO, requires C = 57.9 ; H = 6.9 per cent. Tropine Methonitrate. This was obtained in an attempt to prepare hornatropine metho- nitrate by heating together homatropine and methyl nitrate in methyl alcoholic solution for two hours in a sealed tube a t 100'. The clear solution was evaporated in a vacuum over sulphuric acid, and gave a viscid oil from which a small quantity of crystals separated. These crystallised from absolute alcohol i n large, transparent cubes which began to turn brown at 280°, but did not melt at 300" : 0,2198 gave 0.3982 CO, and 0.1632 H,O. C = 49.4 ; H = 8.3. C8H,,0N,CH,*K03 requires C = 49.5 ; K = S.3 per cent, THE WELLCOYE ~IIEhfICAL WOKKS, DARTFORD, KEST.