Kinetics and a mechanistic investigation of the reaction between dimethyl acetylenedicarboxcylate (DMAD) and saccharin (N–H heterocyclic compound) has been spectrally studied in methanol environment in the presence of tri‑ phenylarsine (TPA) as a catalyst. | Structural effects on kinetics and a mechanistic investigation of the reaction between DMAD and N H heterocyclic compound in the presence of triphenylarsine Spectrophotometry approach