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Part-IExperimental119 o C was 128-138 gm (78-84% of the theoretical amount). The crude product was usedas such in further step.b. Synthesis of chloroacetonitrileIn a 3 litre round-bottomed flask fitted with an efficient mechanical stirrer, a refluxcondenser and a thermometer were placed 170 gm (1.2 mole) of phosphorous pentoxide,187 gm (2 mole) of chloroacetamide and 800 ml of dry technical trimethylbenzene. Themixture was refluxed gently with vigorous stirring for 1 hr. The reaction mixture was thenallowed to cool to about 100 o C with continuous stirring and the reflux condenser wasreplaced with a distilling adapter fitted with a thermometer and a water-cooled condenser.The crude product and part of solvent were distilled at atmospheric pressure. The yield ofcrude product boiling at 124-128 o C was 121-131 gm (80-87%). To obtain pure product,the crude chloroacetonitrile was mixed with 10 g of phosphorous pentoxide andredistilled through an efficient packed fractionating column. The yield of the purechloroacetonitrile distilling at 123-124 o C was 93-106 gm (62-70%).4.1.2 Synthesis of Thiophene o-aminoesters (Ii-xii) 3,41. Synthesis of 2-amino-3-carbethoxy-4,5,6,7-tetrahydrobenzo(b)thiophene(Ii)(Method A)Cyclohexanone (9.8 gm; 0.1 mole), powdered sulfur (3.2 gm; 0.1mole), ethylcyanoacetate (11.7 gm; 0.1 mole) and ethanol (20 ml) were mixed and stirred together atroom temperature. To this well stirred mixture, diethylamine (9.14 gm; 0.125 mole) wasadded dropwise in 0.5 hrs and stirring continued for another 3 hrs at ambient temperature.The reaction mixture was allowed to attain room temperature and thereafter kept inrefrigerator overnight. The solid separated was filtered at suction and washed with 20 mlchilled 50% aq. methanol. The product (18.0 gm; 80% yield) having m.p 110-112 o C(112-115 o C) 5 was characterized as 2-amino-3-carbethoxy-4,5,6,7-tetrahydrobenzo(b)-thiophene (Ii).Mol. Formula : C 11 H 15 NO 2 S; Mol. Wt. 225IR (KBr) cm -1 : 3414, 3306(γ NH ), 3165, 3074, 2988(γ C-H ), 1725(γ COOEt ).UV(MeOH) : 311 nm166