Greizerstein, W.; Bonelli, R. A.; Brieux, J. A. published an article in 1962, the title of the article was Polar effects of substituents on the reaction rates of 4-R and 5-R-2-nitrochlorobenzenes with pipefidine in benzene.Formula: C7H3ClN2O2 And the article contains the following content:
The rate constants for the reaction of fourteen 4-Rand of twelve 6-R-2-nitrochlorobenzenes with piperidine in benzene solution were determined The reactions were carried out at constant temperature in sealed tubes each containing 10 ml. benzene solution of the reactants, 0.1M in the halogen compound and 1.0M in piperidine. Cl- was determined by potentiometric titration after addition of 10 ml. 20% HNO3. Rate constants were calculated by means of the equation k2 = {2.303/[t(b – 2a)]} log {a(b – 2x)/b(a – x)}, where a and b were the molar concentrations of the halogen compound and piperidine, rasp., and x the concentration of Cl- at time t. Data from duplicate runs did not differ by more than 1% and rate constants were reproducible within ±2% by independent experiments A spectrophotometric technique was used for compounds having the substituents: 4-NO2, 3-CN, 4-CO2Et, 4-PhN:N, 4-F3C, and 5-CN. The absorption due to the substituted N-phenylpiperidine produced in the reaction was measured at 390420 mμ with a Beckman DU spectrophotometer. Initial concentrations ranged from 10-4 to 10-5M for the halogen compound and piperidine was 102-103 times in excess. Samples were removed from the thermostat, cooled rapidly to room temperature, and the absorbency measured directly. Pseudomonomol. rate constants were calculated graphically from the plot of O.D.∞exptl.-O.D.t; versus t (O.D, = optical d.); second-order rate constants were obtained from these by dividing by the concentration of piperidine. The results were tabulated and showed that in the nucleophilic substitution of these compounds the polarity of the substituted carbon atom was mainly determined by the overall polar effect of the substituent. The reaction followed the Hammett relationship log kR/kH = σ*ρ. Using Jaffe’s σ* values, which are equivalent to Hammett’s σ-constants for most substituents studied, a ρ-value of +3.80 with a correlation coefficient r = 0.934 resulted. For the 4-R-2-nitrochlorobenzenes, alone a ρ-constant of +4.08 with a correlation coefficient of 0.922 was obtained. In order to estimate the mesomeric interaction between a 5-substituent R and the nitro group para to each other, the values of log k2-5R versus σ*meta were introduced into Hammett’s graphic plot of log k2-4R versus σ*4R with ρ = 4.08. From this, the difference between σ*meta values employed and the amended σ-values fitting the exptl. data into the equation log k2-5R = log k2-H + 4.08. σamended was evaluated for each m-substituent. The differences for most substituents were small, but for m-CN, m-CO2Et, and m-Ph the σamended values were smaller than the σ-constants by 0.24, 0.20, and 0.20 units, resp., showing that the activating influence of the nitro group ortho to the site of reaction was roughly constant but smaller than the overall effect in most compounds studied. 4-Chloro-3-nitrobenzotrifluoride and 4-chloro-3-nitroazobenzene showed an inversion of relative reactivity between 35 and 45°, but the order for the more reactive compounds at 45°, k4-No2 > k4-CN > k4-CO2Et > k4-F3C gt; k4-C6H5N2 > k4-CO2H gt; k4-halogen was that expected from their total polar effects upon the site of substitution. The 3-chloro-4-nitrobenzoic acid reacted slower than the p- and o-substituted isomer. The substituents 4-OMe, 4-OEt, and 4-NH2 were found to be deactivating by their mesomeric effect, while halogens produced a marked increase in the rate, specially from the m-position, due to their neg. inductive effect. A Me group in the m-position gave a slight decrease of the rate, this being more pronounced if Me was in the p-position. The phenyl group slightly enhanced the reactivity from the m-positions, a greater increment being observed from the p-position. The experimental process involved the reaction of 3-Chloro-4-nitrobenzonitrile(cas: 34662-29-8).Formula: C7H3ClN2O2
3-Chloro-4-nitrobenzonitrile(cas:34662-29-8) belongs to nitriles. Some nitriles are manufactured by heating carboxylic acids with ammonia in the presence of catalysts. This process is used to make nitriles from natural fats and oils, the products being used as softening agents in synthetic rubbers, plastics, and textiles and for making amines.Formula: C7H3ClN2O2
Referemce:
Nitrile – Wikipedia,
Nitriles – Chemistry LibreTexts