Research Journal of Recent Sciences ______ ______________________________ ______ ___ __ _ ISSN 2277 - 2502 Vol. 1( ISC - 2011 ), 79 - 84 (201 2 ) Res.J. Recent .Sci. International Science Congress Association 79 Synthesis, characterization and de - tert - butylation of 4 - N - t - butyl - 5 - aryl imino - 1,2,4 triazolidine - 3 - thiones into 5 - arylimino - 1,2,4 triazolidine - 3 - thiones Rashidi N.A and Berad B.N Department of Chemistry, Shri Shivaji Science College, Amravati , MS , INDIA Department of Chemistry, RTM Nagpur University, Nagpur, MS , INDIA Available online at: www.isca.in (Received 10 th October 2011, revised 10 th January 2012 , accepted 24 th January 2012 ) Abstract Triazole is a five membered heterocyclic ring which is a versatile lead compound for designing potent bioactive agents. The derivatives of triazole nuclei showed diverse biological activities. In the present study, we have synthesised some new 4 - N - t - butyl - 5 - arylimino - 1,2,4 - triazole - 3 - thiones (Va - f) from 2 - arylimino - 5 - t - butylimino - 1,3,4 - thiadiazoles (IVa - f).The later compound were prepared by the condensation of N - aryl thiosemicarbazide (IIa - f) and tert - butyl imino isocyanodichloride in chloroform medium. The synthesized compound s (Va - f) were successfully de - tert butylated into 5 - arylimino - 1,2,4 - triazolidine - 3 - thione (VIa - f). All the newly synthesized compounds were subjected to physical characterization and spectral analysis by IR and NMR and Mass for structure elucidation. Keywords : 1,2,4 - triazole 1,3,4 - thiadiazole, Aryl isothiocyanate, N - t - butyl isocyanodichlorides . Introduction The chemistry of heterocyclic compounds continues to be an active field in the organic chemistry. Triazole derivatives have occupied an unique position in heterocyclic chemistry due to their biological activities 1 - 3 . Triazole is any five - membered heterocycle having two carbon, three nitrogen atoms and two double bonds having general formula C 2 H 3 N 3 .The two isomers are 1,2,3 - triazole and 1,2,4 - triazole. 1,2,3 - triazole 1,2,4 - triazole Out of the two triazoles 1, 2, 4 - triazol e has wide variety of activity 4 - 5 . 1,2, 4 - Triazoles as antibacterial agents can be grouped according to the mode of action, i.e. the ability to inhibit the synthesis of the cell wall, cell membrane, proteins and nucleic acids of bacteria. The synthesi s of 1, 2, 4 - triazoles has also attracted wide spread attention due to the divers e agricultural ( such as fungicidal , insecticidal, bactericidal, herbi cidal ) and industrial activities ( dyes, lubricants and analytical reagents, antiviral a gents ) , including anti - inflammatory, analgesic, antitumoral, anticonvulsant and tranquilizing activi ties shown by these compounds 6 - 8 . Examples of such compounds bearing the 1 , 2,4 - triazole moieties are fluconazole, a powerful azole antifungal agent . In view of these observations , in the present study we have synthesized some new derivatives of 1,2,4 - triazoles. The synthesized compounds were subjected to physical characterizat ion and spectral analysis by IR, NMR and Mass for structure elucidation. Material and Methods All the chemicals were purchased from local market and purified according to established method. Melting points were recorded using VEEGO digital melting point apparatus. The homogeneity and purity of synthesized compounds was established by thin layer chromatography (TLC). Precoated silica gel aluminium plate (20 cm x 20 cm wit h 250 µm thickness were used for TLC (E. Merck). Iodine was used to develop the TLC plates. Infrared (IR) spectra were recorded on Perkin Elmer FT - IR spectrophotometer model using nujol and potassium bromide pellets (őmax in cm - 1 ). 1 HNMR spectra were recor ded on Brucker Advance II 400 NMR spectrometer using deuterated dimethyl sulfoxide - containing tetramethyl silane (Me 4 Si) as internal standard (chemical shifts in ĎŚ, ppm). The Mass spectrum was recorded on TOF MS ES+ Mass spectrometer. Six substituted aryl isothiocyanate (Ia - f) were synthesized by the reaction of corresponding amines with carbon disulfide and ammonium hydroxide by following the reported method 9 .Tert - butyl isothiocyanat e was prepared by known procedure 10 . Preparation of t - butyl imino isocyanodichloride 11 : Through a chloroform solution of t - butyl isothiocyanate (6ml in 15ml) chlorine (generated from 10gm KMNO 4 and 70 ml conc. HCl) was passed maintaining the temperature at 15 0 . After addition of chlorine had been completed, the ye llow Research Journal of Recent Sciences ______ _ _ _______________________________ ______________ _ ______ ISSN 2277 - 2502 Vol. 1( ISC - 2011 ), 79 - 84 (201 2 ) Res.J.Recent.Sci International Science Congress Association 80 reaction mixture was diluted with 40 ml dry petroleum ether (60 0 - 80 0 ) and filtered to remove suspended impurities. The solvent was then removed by distillation under vaccum. The whole operation is repeated with 40 ml petroleum ether and finally petrol eum ether solvent was distilled off, t - butyl iso cyanodichloride (10 ml) in the form of yellow oil was collected. Synthesis of N - p - tolyl thiosemicarbazide 12,13 (I Ia) : Dissolved p - tolyl iso thiocyanate (Ia) as (0.01 mol) in 20 ml chloroform and hydrazine hydrate (99%) (0.01 mol) was added drop wise to the reaction mixture with stirring. The reaction was found to be exothermic. The resulting mixture was allowed to cool. The white solid separated within 10 minutes , was filtered, washed with water and dried. Recrystallised the product (IIa) with ethanol. The above reaction was extended to synthesize compounds (IIb - f) S ynthesis of 2 - p - tolylimino - 5 - N - t - butylimino - 1, 3,4 - thiadiazol es (IVa) : The N - p - tolyl thiosemicarb azide (IIa ) and t - butyl imino isocyanodichloride in equimolar proportion were refluxed in chloroform medium for 3 hr. The evolution of hydrogen chloride gas was observed. After completion of reaction, distilled off solvent, afforded a sticky mass which on washing with petroleum ether (60 0 - 80 0 ) followed by addition of little amount of ethanol gave a pale yellow solid. It was crystallized from ethanol. The resultant solid was found to be mono hydrochloride (IIIa ). Basification of it with aqueous amm onia affo rded a free base (IVa ), crystallized from aqueous ethanol (70% ) , m.p 102 0 C . The product was soluble in organic solvent but insoluble in water and gave positive test for N and S elements. On extending the above reaction to other N - aryl thiosemicarbazide, the related 1,3,4 - thiadiazoles were isolated in good yield. ( IVa ) : IR spectra 14 : (KBr) cm - 1: 3392 (NH), 3228(NH), 3180 - 3112(Ar - H), 3026 - 2980 (C - H, t - Bu), 2918,2856(C - H),1487 (C=N), 1313 (C - N), 810 (C - S); 1H - NMR (DMSOd6) ppm: 1.2 - 1.6 (9H, m, t - Bu), 2.1(3H, s, CH 3 ) 6.92 - 7.2 (4H, m, Ar - H), 7.3 (1H, d, NH), 7.4(1H, d, NH) ( IVc ) IR: (KBr) cm - 1 3391(N - H) 3195 - 3138(Ar - H), 2969 - 2795 C - H),1613 (C=N), 1167 (C - N), 774(C - S); 1H - NMR (DMSOd6) ppm: 1.2 - 1.6 (9H, m, t - Bu), 2.1(3 H, s, CH 3 ) 6.92 - 7.2 (4H, m, Ar - H), 7.4 (1H, d, NH), 8.4(1H, d, NH) S ynthesis of 4 - N - t - butyl - 5 - p - tolyl imino - 1,2,4 - triazolidine - 3 - thiones (Va) : The 2 - p - tol ylimino - 5 - N - t - buty limino - 1,3,4 - thiadiazoles (IVa ) were refluxed with 5% ethanolic NaOH for 1.5 hr, where the compound (IVa ) underwent isomerisatio n. After completion of reaction , the reaction mixture was cooled and poured in ice crushed water. The solid that separated was collected, drie d and crystallized from ethanol, m.p122 0 C. The product (Va ) was s oluble in organic solvent but insoluble in water. Sulphur and nitrogen element test gave the positive result for the product. The above reaction was extended to synthesize compounds (Vb - f) (Va) : IR spectra :(KBr) cm - 1 : 3392 (N - H), 3238(N - H), 3183 - 3111 (Ar - H),3031 - 2959 (C - H,t - Bu), 2917,2849(C - H,CH 3 ),1514(C=N), 1316 (C - N), 1218(C=S) (Va) : Mass (m/z) : 264 [M+], 207, 192, 163,133 (Vc) IR spectra: (KBr) cm - 1 : 3198 (N - H), 3139 (Ar - H), 2955 - 2849 C - H),1485 (C=N), 1295(C - N), 1262(C=S) 1H - NMR (DMSOd6) ppm: 1.2 - 1.6 (9H, m, t - Bu), 2.1(3H,s,CH 3 ) 6.92 - 7.2 (4H, m, Ar - H), 7.4 (1H, d, NH), 8.4(1H, d, NH) S ynthesis of 5 - p - tolyl imino - 1,2,4 - triazolidine - 3 - thiones (VIa) : The product 4 - N - t - butyl - 5 - p - tol yl imino - 1,2,4 - triazolidine - 3 - thiones (Va) when sub jected to hyd rolysis with boiling 30% sulphuric acid under reflux for 3 hr, the solid gradually went into solution an d a clear solution was obtained . After completion of reaction , the reaction mixture was cooled and poure d in ice crushed water. The product that separated was collected, dried and crystallized . The product obtained was found to be de - tert - butylated 15 ( IVa ) , m.p 142 0 C and gave positive test for N and S elements.The above reaction was extended to synthesize compounds (VIb - f) (VIa ) 1 H - NMR : (DMSOd6) ppm : δ 2.2 (3H, s, CH 3 ), 7.00 (2H, d, Ar - H) 7.3(2H, d, Ar - H), 4.9(2H, N - H) and 10.2 ppm (1H, s, N - H); Results and Discussion Six substituted aryl isothiocyanate (Ia - f) were synthesized by the reaction of corresponding amines with carbon disulfide and ammonium hydroxide. The N - aryl thiosemicarbazides ( IIa - f) were prepared by the treatment of isothiocyanate with hydrazine hydrate in chloroform medium 11 . The condensation of N - p - tolyl thiosemicarbazide (IIa ) with t - butyl imino isocy anodichlor ide in chloroform was carried out for 3 hr. The evolution of hydrogen chloride gas was observed and tested with moist blue litmus paper. Cooling the reaction mixture and distilling off the solvent afforded a sticky mass, which on washing with petroleum eth er followed by addition of a little ethanol gave a light yellow solid. It was crystallized from aqueous ethanol (70%), m.p 72 - 74 0 C. It was acidic to litmus. On determination of equivalent weight it was found to be mono hydrochloride (IIIa). O n basification with ammonium hydroxide, afforded a free base (IVa) crystallized from aqueous ethanol, m.p102 0 C. On the basis of spectral data IR and 1H NMR and above facts the compound (IVa) has been assigned the structure as 2 - p - tol yl imino - 5 - t - butylimino - 1,3,4 - thiadia zole . The other compounds (IVb - f) were prepared by extending the above reaction to other N - aryl thiosemicarbazides (IIb - f) and the related 1,3,4 - thiadiazole (IVb - f) were isolated in good Research Journal of Recent Sciences ______ _ _ _______________________________ ______________ _ ______ ISSN 2277 - 2502 Vol. 1( ISC - 2011 ), 79 - 84 (201 2 ) Res.J.Recent.Sci International Science Congress Association 81 yield ( t able1). The product (IVa) was allowed t o react with 5% ethanolic NaOH at reflux for 1.5 hr where it underwent isomeriz ation . On the basis of elemental data and spectral analysis of isomerised product (Va), it was found to be 4 - N - t - butyl - 5 - arylimino - 1 ,2,4 - triazolidine - 3 - thione . The Mass spectra of compound (Va) showed [M+] peak at m/z 264 and a base peak at m/z 207(100%).The other compounds (Vb - f) were prepared by following the similar method (Table 2). The resultant product (Va) was further converted into 5 - p - tol yl imino - 1,2 ,4 - triazolidine - 3 - thione (VIa ) by refluxing with 30% sulphuric acid underwent de - t - butylation. The structure of 5 - p - tol yl imino - 1,2 ,4 - triazolidine - 3 - thione (VIa ) was confirmed by 1 H NMR spectral data. The 1 H NMR spectra of 4 - N - t - butyl - 5 - p - tol yl imino - 1 ,2,4 - triazolidine - 3 - thione (Va ) showe d a multiplet in the range 1.2 - 1.6 attributed to the C - H of t - butyl group. The absence of signals due to C - H of t - butyl group in 1 H NMR spectra of product (VIa) confirmed that compound (Va ) was successfully de - tertbutylated into 5 - arylimino - 1, 2,4 - triazolid ine - 3 - thione (VIa ) . The above reaction was extended to synthesize compounds (VIb - f) (table 3). The elemental analysis and spectral data IR, 1 H - NMR and Mass of all the synthesized compounds was in full agreement with the proposed structures. The synthetic route is outlined in Scheme . ( fig 1 ) P HYSICAL CHARACTERISATION Table - 1 Formation of 2 - Arylimino - 5 - N - t - butylimino - 1,3,4 - thiadiazoles (IV) Reagent : Aryl thiosemicarbazide(II) and t - butyl imino isocyanodichloride Note : All the compounds gave satisfactory C, H, Cl, and S analysis Aryl thiosemicarbazide(II) 2 - Aryl imino - 5 - N - t - butylimino - 1,3,4 - thiadiazoles hydrochlorides(III). Yield % M.P 0 C Eq. wt. Found (calcd) 2 - Aryl imino - 5 - N - t - butylimino - 1,3,4 - thiadiazoles (IV) (Free base) . M.P 0 C N % Found (Calcd) p - Tolyl thiosemicarbazid(IIa) 2 - p - Tolyl imino - 5 - N - t - butylimino - 1,3,4 - thiadiazoles hydrochlorides(IIIa). 78 72 - 74 296.3 (298.8) 2 - p - Tolyl imino - 5 - N - t - butylimino - 1,3,4 - thiadiazoles (IVa). 102 21.30 (21.35) P henyl thiosemicarbazide(IIb) 2 - P henyl…..1,3,4 - t h iadiazole hydrochloride(IIIb) 80 96 - 98 282.8 (284.8) 2 - Phenyl imino - 5 - N - t - butylimino - 1,3,4 - thiadiazole (IVb) 144 22.50 (22.56) o - T olyl thiosemicarbazide(IIc) 2 - o - T olyl…..1,3,4 - t h iadiazole hydrochloride(IIIc) 75 88 - 90 297.3 (298.8) 2 - o - Tolyl imino - 5 - N - t - butylimino - 1,3,4 - thiadiazole (IVc) 115 21.33 (21.35) m - T olyl thiosemicarbazide(IId) 2 - m - T olyl…..1,3,4 - t h iadiazole hydrochloride(IIId) 67 80 - 82 295.4 (298.8) 2 - m - Tolyl imino - 5 - N - t - butylimino - 1,3,4 - thiadiazole(IVd) 164 20.60 (21.35) o - Ch loro thiosemicarbazide(IIe) 2 - o - Chloro phenyl….1,3,4 - thiadiazole hydrochloride(IIIe) 65 93 - 95 317.4 (319.2) 2 - o - Chloro phenyl imino - 5 - N - t - butylimino - 1,3,4 - thiadiazole(IVe) 110 19.05 (19.81) p - C hloro thiosemicarbazide(IIf) 2 - p - Chloro phenyl…. 1,3,4 - t h iadiazole hydrochloride(IIIf) 81 60 - 62 316.1 (319.2) 2 - p - Chloro phenyl imino - 5 - N - t - butylimino - 1,3,4 - thiadiazole (IVf) 156 19.77 (19.81) Research Journal of Recent Sciences ______ _ _ _______________________________ ______________ _ ______ ISSN 2277 - 2502 Vol. 1( ISC - 2011 ), 79 - 84 (201 2 ) Res.J.Recent.Sci International Science Congress Association 82 Table - 2 Formation of 4 - N - t - butyl - 5 - aryl imino - 1 ,2,4 - triazolidine - 3 - thiones(V) Reagent : 2 - Aryl imino - 5 - N - t - butylimino - 1,3,4 - thiadiazoles (IV) and NaOH in ethanol (5%). 2 - Aryl imino - 5 - N - t - butylimino - 1,3,4 - thiadiazoles (IV). 4 - N - t - butyl - 5 - aryl imino - 1,2,4 - triazolidine - 3 - thiones(V) Yield % M.P 0 C Mol Formula N % found (Calcd) 2 - p - Tolyl imino - 5 - N - t - butylimino - 1,3,4 - thiadiazoles (IVa). 4 - N - t - butyl - 5 - p - tolyl imino - 1,2,4 - triazolidine - 3 - thiones(V a ) 73 122 C 13 H 18 N 4 S 21.50 (21.35) 2 - Phenyl imino - 5 - N - t - butylimino - 1,3,4 - tiadiazole (IVb) 4 - N - t - butyl - 5 - phenyl imino - 1,2,4 - triazolidine - 3 - thiones(V b ) 80 141 C 1 2 H 1 6 N 4 S 22.10 (22.56) 2 - o - Tolyl imino - 5 - N - t - butylimino - 1,3,4 - tiadiazole (IVc) 4 - N - t - butyl - 5 - o - tolyl imino - 1,2,4 - triazolidine - 3 - thiones(V c ) 70 168 C 13 H 18 N 4 S 20.60 (21.35) 2 - m - Tolyl imino - 5 - N - t - butylimino - 1,3,4 - tiadiazole (IVd) 4 - N - t - butyl - 5 - m - tolyl imino - 1,2,4 - triazolidine - 3 - thiones(V d ) 71 185 C 13 H 18 N 4 S 21.32 (21.35) 2 - o - Chloro phenyl imino - 5 - N - t - butylimino - 1,3,4 - tiadiazole (IVe) 4 - N - t - butyl - 5 - o - chloro phenyl imino - 1,2,4 - triazolidine - 3 - thiones(V e ) 67 136 C 12 H 15 Cl N 4 S 19.16 (19.81) 2 - p - Chloro phenyl imino - 5 - N - t - butylimino - 1,3,4 - tiadiazole (IVf) 4 - N - t - butyl - 5 - p - chloro phenyl imino - 1,2,4 - triazolidine - 3 - thiones(V f ) 78 166 C 12 H 15 Cl N 4 S 19.77 (19.81) Note : All the compounds gave satisfactory C, H, Cl, and S analysis Table 3 Formation of 5 - Aryl imino - 1,2,4 - triazolidine - 3 - thiones(VI). Reagent : 4 - N - t - butyl - 5 - aryl imino - 1,2,4 - triazolidine - 3 - thiones(V) and 30% H 2 SO 4 . 4 - N - t - butyl - 5 - aryl imino - 1,2,4 - triazolidine - 3 - thiones(V) 5 - Aryl imino - 1,2,4 - triazolidine - 3 - thiones (VI) M.P 0 C 4 - N - t - butyl - 5 - p - tolyl imino - 1,2,4 - triazolidine - 3 - thiones(Va) 5 - p - T olyl imino - 1,2,4 - triazolidine - 3 - thiones (VIa) 142 4 - N - t - butyl - 5 - phenyl imino - 1,2,4 - triazolidine - 3 - thiones(Vb) 5 - P henyl imino - 1,2,4 - triazolidine - 3 - thiones (VIb) 134 4 - N - t - butyl - 5 - o - tolyl imino - 1,2,4 - triazolidine - 3 - thiones(Vc) 5 - o - T olyl imino - 1,2,4 - triazolidine - 3 - thiones (VIc) 100 4 - N - t - butyl - 5 - m - tolyl imino - 1,2,4 - triazolidine - 3 - thiones(Vd) 5 - m - T olyl imino - 1,2,4 - triazolidine - 3 - thiones (VId) 118 4 - N - t - butyl - 5 - o - chloro phenyl imino - 1,2,4 - triazolidine - 3 - thiones(Ve) 5 - o - Chloro phenyl imino - 1,2,4 - triazolidine - 3 - thiones (VIe) 178 4 - N - t - butyl - 5 - p - chloro phenyl imino - 1,2,4 - triazolidine - 3 - thiones(Vf) 5 - p - C hloro phenyl imino - 1,2,4 - triazolidine - 3 - thiones (VIf) 152 Note : All the comp ounds gave satisfactory C, H, N and S analysis Research Journal of Recent Sciences ______ _ _ _______________________________ ______________ _ ______ ISSN 2277 - 2502 Vol. 1( ISC - 2011 ), 79 - 84 (201 2 ) Res.J.Recent.Sci International Science Congress Association 83 Conclusion Triazole moiety and its various derivatives studied frequently in the past time and found potent in various pharmacological and pathological conditions. In the article the attempt to synthesize and characterize triazole derivatives were successfully carried out with elaborate characterization by spectral data. Obtained spectral data has prompted us to further evaluate the possible information from the spectra to understand synthetic approach and the dynamic property of m olecules synthesized. These synthesized compounds are expected to possess biological activities. Acknowledgement The authors are grateful to the Principal, Shri Mungsaji Maharaj Mahavidyalaya, Darwha for allowing to carry out research work. The authors ar e also grateful to the Principal Dr. V. G. Thakare, Shri. Shivaji Science College, Amravati, for providing all e ssential laboratory facilities as well as to The Director , RSIC, Punjab University , Chandigrah for prviding elemental anlysis and IR,PMR, Mass Spectral data. References 1. Hartwell J.L. and B.J. 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Soc., 1635 (1960) Research Journal of Recent Sciences ______ _ _ _______________________________ ______________ _ ______ ISSN 2277 - 2502 Vol. 1( ISC - 2011 ), 79 - 84 (201 2 ) Res.J.Recent.Sci International Science Congress Association 84 SCHEME 5 www.ijps.info I CHCl 3 N - aryl thiosemicarbazide (II) t - butyl - imino isocyanodichloride CHCl 3 , Reflux NH 4 OH 2 - arylimino - 5 - t - butylimino - 1,3,4 - thiadiazole 2 - arylimino - 5 - t - butylimino - 1,3,4 - thiadiazole Hydrochloride (III) (IV) 5% ethanolic NaOH Reflux 30% H 2 SO 4 5 - arylimino - 1,2,4 - triazolidine - 3 - thione (VI) 4 - N - t - butyl - 5 - arylimino - 1,2,4 - triazolidine - 3 - thione (V) Where R - (I, II, III, IV , V, VI ) a = p - tolyl, b = phenyl, c = o - tolyl, d = m - tolyl, e = o - chloro phenyl, f = p - chloro phenyl Scheme . 1: - Scheme for synthesis of tri azole derivatives