Refrachor (<i>F</i>) – seventy-year-old tool and a contemporary observation: estimation of equilibrium compositions of 1<i>H</i>- and 2<i>H</i>-tautomers of tetrazole and 1,2,3-triazole and imine–amine composition of acetaldimine–vinylamine tautomeri

Abstract Refrachor with a symbol F a new physical constant proposed for the first time in 1951 by Joshi and Tuli defined by the equation F = – P log( <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <m:mrow> <m:msubsup> <m:mi>n</m:mi> <m:mi mathvariant="normal">D</m:mi> <m:mn>20</m:mn> </m:msubsup> </m:mrow> </m:math> ${n}_{\mathrm{D}}^{20}$ –1) where P is the parachor and <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <m:mrow> <m:msubsup> <m:mi>n</m:mi> <m:mi mathvariant="normal">D</m:mi> <m:mn>20</m:mn> </m:msubsup> </m:mrow> </m:math> ${n}_{\mathrm{D}}^{20}$ is the refractive index, is now used in our present work to calculate the percentage composition of 1 H - and 2 H -tautomers of tetrazole, 1,2,3-triazole, and imine-enamine tautomerism of acetaldimine in their equilibrium mixtures.