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General procedure: Phenethylamine (300.0 g, 2.48 mol) and triethylamine (350.6 g, 3.46 mol) were placed in a 5000 mL three-neck round bottom flask, and ethyl acetate (1000 mL) was added, and then the mixture was cooled in an ice bath and mechanically stirred. When the temperature of the mixed solution was dropped to 0 C.-5 C., carbon disulfide (339.2 g, 4.45 mol) was slowly added dropwise by a constant pressure dropping funnel, magnetic stirring as dropping, and the temperature of the reaction liquid was controlled to be less than 30 C. After the dropwise addition was completed, magnetic stirring was carried out for one hour at room temperature (10-30 C.); BOC2O (535.1 g, 2.45 mol) and DMAP catalyst were added to the reaction solution at this temperature, and then the mixture was stirred to react at 30+-2.5 C. for 1.5 h. After the completion of the reaction, the reaction solution was washed twice with acid solution, and the total amount of acid consumed by washing was 1.5 times that of triethylamine, and then washed with a saturated saline solution until neutral. The organic phase was concentrated by rotary evaporation to give an acid pickling crude. The acid pickling crude was placed in a flask heated by a heating mantle, and a rotary vane vacuum pump was adopted, and a fraction of 130 C.-145 C./10 mmHg was collected to obtain a crude product. The crude distillation product was placed in a rectifying still. The rectifying column specification was phi30*1000 mm, with stainless dixon packing (phi4*4 mm), 2X-8A model rotary vane vacuum pump, the kettle temperature was kept at 160-200 C. After fully refluxed for 0.5 h, the fractions at 95 C.-110 C./200-600 Pa were collected. The front fraction had a reflux ratio of 90:10; after 0.5 hours, the reflux ratio was 50:50, and the middle fraction was collected; finally, the reflux ratio was 70:30, and the post fraction was collected to obtain phenethyl isothiocyanate product (yield 85%), and then identification and purity check was performed.Example 2 Structure and Purity Check of Phenylethyl Isothiocyanate (0107) 1. Structure Identification Result of H-NMR and Spectrum (0108) The results of the nuclear magnetic test are as follows, which is the same as our target product. (0109) 1H NMR (400 MHz, CDCl3) delta 7.37-7.31 (m, 1H), 7.28 (ddd, J=10.2, 5.0, 2.1 Hz, 1H), 7.23-7.19 (m, 1H), 3.72 (t, J=7.0 Hz, 1H), 2.99 (t, J=7.0 Hz, 1H). (0110) Nuclear magnetic detection is shown in FIG. 1. (0111) 2. Purity Detection of Phenethyl Isothiocyanate (0112) Instrument conditions: Dionex U3000, C18 bonded silica gel column, 208/244 nm, 1.0 ml/min, column temperature was 30 C., 10 ul of injection sample, and analysis for 30 min; (0113) The mobile phase was with the gradient of 0 min 40% acetonitrile, 15 min 62.5% acetonitrile, 23 min 100% acetonitrile, 25 min 100% acetonitrile, 25.1 min 40% acetonitrile, 30 min 40% acetonitrile. (0114) Sample configuration: about 15 mg of phenethyl isothiocyanate was weighed precisely, and then placed in a 25 ml measuring flask, dissolved with acetonitrile to volume to scale, filtered and injected; (0115) Result: [table-us-00001-en] Phenylethyl Normalized isothiocyanate main peak related substances 208 nm 99.85% A total of 2 major impurities, accounting for 0.04% and 0.05% respectively 244 nm 99.92% One impurity, accounting for 0.08% (0116) Chromatograms are shown in FIG. 2-1 and FIG. 2-2. |
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