as used herein , the term &# 34 ; alkyl &# 34 ; means straight or branched alkyl chains of 1 to 10 carbon atoms . &# 34 ; aryl &# 34 ; means a phenyl or naphthyl ring , or a phenyl or naphthyl ring substituted with 1 - 3 alkyl substituents . also included within the scope of the invention are salts formed with pharmaceutically acceptable acids such as hydrochloric , hydrobromic , oxalic , tartaric , maleic , fumaric , methane sulfonic and the like . the salts may be formed by conventional means , as by reacting the free acid or base forms of the product with one or more equivalents of the appropriate base or acid in a solvent or medium in which the salt is insoluble , or in a solvent such as water which is then removed in vacuo or by freeze - drying or by exchanging the cations of an existing salt for another cation on a suitable ion exchange resin . compounds of formula i have at least one asymmetrical carbon atom and , therefore , include various stereoisomers . the invention includes all such isomers both in pure form and in admixture , including racemic mixtures . the hydrogenolysis system preferably also comprises an inert solvent , such as methanol , ethanol , isopropanol , dimethylformamide , with methanol being particularly preferred . a preferred starting composition for the hydrogenolysis system based upon the weight of starting material of formula i comprises : a . about 25 to about 600 wt % hydrogenolysis catalyst , preferably about 75 to about 150 wt %; b . about 60 to about 850 wt % preferably about 150 to about 250 wt % hydrogen donor ; and , c . about 800 to about 4000 wt % solvent , preferably about 1500 to about 2100 wt %. the reaction preferably is carried out under mild conditions i . e . about 15 ° to about 150 ° c . at a pressure of about 0 . 9 to about 4 . 5 atmospheres . the reaction more preferably is carried out at up to 100 ° c . and atmospheric pressure , in a well - stirred reaction vessel . a particularly preferred embodiment of the present invention comprises hydrogenolysis of a compound of the formula ## str6 ## to a compound of the formula ## str7 ## as set forth in detail below . the title compound was prepared from a commercial sample of ( s )-(-)- 4 ( 2 - amino - 3 - hydroxypropyl )- imidazole ( aldrich chemical co ., milwaukee , wis ., u . s . a .) according the procedures set forth by gerhard and schunack in arch . pharm . vol . 313 pages 709 - 714 ( 1980 ). s -(-)- 4 -( 2 - amino - 3 - hydroxypropyl )- imidazole ( 124 . 1 g ) in sulfolane ( 2 . 5 kg ) was heated with thionyl chloride ( 2 . 0 kg ) for approximately 90 minutes the mixture was then stirred at 60 ° c . for 19 hours , allowed to cool to 30 ° c ., and filtered . the precipitate from the reaction mixture was taken into 3 . 5 liters of boiling ethanol , charcoal treated , and filtered . the filtrate was concentrated to 1 . 0 liter . a solid was formed , which was filtered , washed first with ethanol , then with et 2 o , and dried . the compound had the following physical properties : m . p = 199 °- 201 ° c . ( d .) ( from ethanol ); [ α ] d 26 =+ 17 . 6 °( c = 1 . 04 , h 2 o ); 13 c nmr ( dmso - d 6 ): 134 ( c - 2 ), 127 ( ch 2 ), 118 ( c - 5 ), 50 ( ch 2 cl ), 44 ( chnh 2 ), 25 ( ch 2 ); ms : 160 ( 2 , m + ), 110 ( 14 ), 82 ( 90 ), 81 ( 86 ), 80 ( 12 ), 78 ( 38 ), 55 ( 18 ), 54 ( 21 ), 44 ( 6 ), 43 ( 15 ), 42 ( 19 ). to a stirred solution of the product of preparative example 1 ( 9 . 6 g , 41 mmol ) in dry methanol ( 240 ml ) under nitrogen were added 10 % pd / c ( 12 . 0 g ) and anhydrous ammonium formate ( 20 . 5 g , 325 mmol ). the resulting mixture was refluxed under nitrogen for three hrs . the cooled mixture was filtered through diatomaceous earth , and the mixture of filter aid and catalyst was washed with methanol ( 200 ml ), dichloromethane - methanol ( 1 : 1 by vol , 200 ml ), and dichloromethane ( 800 ml ). the combined filtrates deposited a precipitate which was removed by filtration , washed with dichloromethane , and discarded . combined filtrates again gave a precipitate which was similarly removed , washed , and discarded . when no more precipitate formed on dilution of the combined filtrates with dichloromethane , solvents were evaporated to give the unpurified title compound ( 6 . 2 g ), as a foam having the following physical properties 1 h nmr ( 200 mh z , dmso - d 6 ): 7 . 70 ( s , 1h , h - 2 ), 7 . 0 ( s , 1h , h - 4 ), 3 . 41 ( sextet , 1h , ch ( me ) nh + 3 ), 2 . 87 ( dd , 1h , j a - b = 14 . 5 , j a - ch = 5 . 6 , ch a h b ), 2 . 70 ( dd , 1h , j a - b = 14 . 5 , j b - ch = 8 . 0 , ch a h b ). 1 . 16 ( d , 3h , j = 6 . 3 , ch 3 ); 13 c nmr : 17 . 3 ( ch 3 ), 30 . 8 ( ch 2 ), 46 . 4 ( chnh + 3 ), 115 . 6 ( c - 5 ), 132 . 5 ( c - 4 ), 132 . 4 ( c - 2 ); ms ( fab ): 126 ( 100 , [ m + 1 ] + ). analytically pure title compound was obtained from the title compound of example 1 by the following procedure . an aqueous solution of the title compound of example 1 ( 6 . 2 g ) was passed through a column containing 120 g of amberlite ® 1ra - 400 ( oh ) ion exchange resin ( rohm and haas company , philadelphia , pa ., u . s . a .) packed in h 2 o . removal of the solvent from the effluent under reduced pressure gave the free base ( 3 . 87 g ), which was dissolved in absolute etoh ( 50 ml ) and was cooled in an ice bath . saturated ethanolic hcl ( 70 ml ) was added , after which the title compound ( 6 . 0 g ) was recrystallized from 2 - proh - me 2 co , m . p . 174 °- 176 ° c . starting compounds where the aliphatic substituent is other than 2 - amino - 3 - chloropropyl may be prepared by methods analagous to that set forth in preparative example 1 and by other methods well known in the art . dehalogenated compounds within the scope of compound ii prepared from compounds of generalized structure i where the alkyl substituent is other than 2 - aminopropyl may be prepared generally by following the methods of examples 1 and 2 above . pharmaceutical formulations utilizing dehalogenated compounds prepared in accordance with the present invention are set forth below . ______________________________________no . ingredient mg / tablet mg / tablet______________________________________1 . active compound 100 5002 . lactose usp 122 1133 . corn starch , food grade , 30 40as a 10 % paste in purified water4 . corn starch , food grade 45 405 . magnesium stearate 3 7total 300 700______________________________________ mix item nos . 1 and 2 in suitable mixer for 10 - 15 minutes . granulate the mixture with item no 3 . mill the damp granules through a coarse screen ( e . g ., 1 / 4 &# 34 ;, 0 . 63 cm ) if necessary . dry the damp granules . screen the dried granules if necessary and mix with item no . 4 and mix for 10 - 15 minutes . add item no . 5 and mix for 1 - 3 minutes . compress the mixture to appropriate size and weight on a suitable tablet machine . ______________________________________no . ingredient mg / capsule mg / capsule______________________________________1 . active compound 100 5002 . lactose usp 106 1233 . corn starch , food grade 40 704 . magnesium stearate nf1 4 7total 250 700______________________________________ mix item nos . 1 , 2 and 3 in a suitable blender for 10 - 15 minutes . add item no . 4 and mix for 1 - 3 minutes . fill the mixture into suitable two - piece hard gelatin capsules on a suitable encapsulating machine . while the present invention has been described in connection with certain specific embodiments thereof , it will be evident to one of ordinary skill in the art that many alternatives , modifications and variations may be made . all such alternatives , modifications and variations are intended to be included within the spirit and scope of the invention .