Abstract
The synthesis of dicarbonitrile was realized according to described method of Begland. The procedure was slightly modernized by us to save reagents and increase the yield of the target compound. The concentration dissociation constants of 2,3-dicyano-5,7,7-trimethyl-6,7-di hydro-1H-1,4-diazepi ne were determined by a potentiometric method: pK1 = 7.46 +/- 0.05 (I = 0.1); pK1 = 7.53 +/- 0.03 (I = 0.25); pK1 = 7.65 +/- 0.05 (I = 0.5) background electrolyte potassium nitrate temperature 298.15 K. The enthalpies of dissolution of crystalline 2,3-dicyano-5,7,7-trimethyl-6,7-dihydro-1H-1,4-diazepine in aqueous KOH solutions at 298.15 K were measured using the direct calorimetric method in a wide concentration range. The values of the standard enthalpies of combustion and formation of 2,3-dicyano-5,7,7-trimethyl-6,7-dihydro-1H-1,4-diazepine were calculated by the additive group method. The standard enthalpies of the formation of 2,3-dicyano-5,7,7-trimethyl-6,7-dihydro-1H-1,4-diazepine and its dissociation products in an aqueous solution are calculated. (C) 2018 Elsevier B.V. All rights reserved.