A Kinetic Study of the Hydrolysis of Benzalaniline

Abstract

The rates of the acid catalyzed hydrolysis of a series of para substituted benzalanilines have been studied in 50/50 methanol-water in the presence of acetate buffers. Special and general acid catalysis were observed. The effect of para substituents on the rate is different for the charged and uncharged catalyst, and Hammett's relation cannot be applied. Similarly the effect of substituents on the Arrhenius constants for the two cases is different. The para dimethylamino derivative provides a n interesting special case. For low buffer concentrations and in unbuffered solutions certain deviations were observed which show that the ' dependence of the rate on the catalyst concentration is Inore complicated than the equationIn a study of the hydrolysis of benzalanilines reported by Porai-ICoshits and co-workers (4) the effects of certain para substituents seemed so unusual as to warrant reinvestigation. That work was done in water, in the presence of strong acids, the reaction being followed by titration methods. A more convenient method was available to us since the ultraviolet absorption of benzalaniline, in the region of 320-350 mp, is much larger than for a mixture of benzaldehl.de and aniline (Fig. I). By this means, a kinetic study of the acid catalyzed hydrolysis of benzalaniline and some para substituted derivatives with Me, MeO, C1, NOz, and (CH3)2N was carried out. Because it was found that the solubility of these substances was too low in pure water, a Manuscript received i n original form July 15, 1952, and as revised, December 15, 1952. Cotztribution from the Division of Pure Chemistry, National Research Laboratories, Ottawa. Issued as N.R.C. No. 2940. This pa$er was presented at the Bz~Jalo meeting of the American Chemical Society, before the Physical and Inorganic Chemistry Division, program No. 29, i n March, 1952. National Research Laboratories Postdoctorate Fellow, 1950-52 For personal use only.

Electrochemistry of Conductive Polymers: VI . Degradation Reaction Kinetics of Polyaniline Studied by Rotating Ring‐Disk Electrode Techniques

“…In Fig. llb Whatever the mechanism, an increase in rate at constant pH by phosphate, acetate, and other conjugate bases has been routinely observed in a variety of Schiff base hydrolysis reactions (19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29). In view of this, our data showing a rate enhancement by sulfate at pH = 1 should come as no surprise.…”

The Meyer Reaction of Phenylnitromethane in Acid. II. Reactions in Acid of Benzonitrile Oxide and Benzohydroxamic Acid

“…The two effects (on reactions 5 and 6) are in opposition, but in the present instance the effect of the m-nitro group on reaction 5 is greater than its effect on reaction 6, so that a slower reaction results. A similar result has been reported for the acid-catalyzed hydrolysis of benzalanilines (12) and benzamides (13). Jencks (14) has recently discussed this balance between the substituent effects for a rate-determining step and a preceding equilibrium.…”

Saccharide-accelerated hydrolysis of boronic acid imines

“…Structure-activity relationships of N-benzylidineaniline derivatives have been previously examined and a change in the rate-determining step of the reaction was observed, with the hydrogen-substituted compounds having the highest reactivity. 21,22 This was also observed in the hydrolysis of salicylidineanilines derivatives and a simplified reaction sequence has been used to explain this kinetic behaviour. 20 Based on the sequence proposed by Hoffmann; the first step involves addition of a proton to the imine nitrogen, the second, addition of water to the protonated imine and the third involves the decomposition of this species into the products of hydrolysis via the tetrahedral carbinolamine intermediate proposed by Jencks and co-worker 23,24 (Scheme 6).…”