Chemometrical analysis of substituent effects. XIII. Comparison of substituent effects on dissociation and chemical shift in 13C NMR spectra of mono- and disubstituted benzoic acids was written by Kulhanek, Jiri;Pytela, Oldrich;Lycka, Antonin. And the article was included in Collection of Czechoslovak Chemical Communications in 2000.SDS of cas: 5344-49-0 This article mentions the following:
The 13C chem. shifts have been measured of the carboxyl carbon atoms for all the 2-, 3-, and 4-substituted benzoic acids with H, CH3, CH3O, F, Cl, Br, I, and NO2 substituents, as well as for all 3,4-, 3,5-, and 2,6-disubstituted benzoic acids with combinations of CH3, CH3O, Cl (or Br), NO2 substituents and for sym. 2,6-disubstituted derivatives with Et, EtO, PrO, i-PrO, and BuO substituents. The chem. shifts of carboxylic group carbon atoms of the 3- and 4-substituted derivatives show correlation only with the substituent constants σ1. For the 2-substituted derivatives was found the dependence only on σ1 and on the υ constant describing steric effects (s = 0.122, R = 0.996, without the CH3 derivative which has a distinct anisotropic effect). The substituent effects on the carboxylic carbon chem. shift show additivity with 3,4-, 3,5-, and 2,6-substituents, and the 2,6-disubstituted derivatives show a linear synergic effect of substituents due obviously to the steric hindrance to resonance. Application of the principal component anal. to the data matrix involving all the combinations of mono- and disubstitution involving the above-mentioned substituents has proved an identical substituent effect from all the positions on the chem. shift described by one latent variable, steric effects and anisotropic behavior of Me at the 2 and 2,6 positions being predominantly described by the second latent variable (with the total explained variability of 99.5%). Comparison of substituent effects on the chem. shift of carboxylic carbon with that on the dissociation constant measured in the same solvent has confirmed the anisotropy due to ortho Me group, the ortho halogen substituents in monosubstituted derivatives also having a different effect. The dependence of chem. shift on pKa was not very close for the derivatives studied (s = 1.005, R = 0.690). The inclusion of anisotropy of ortho alkyl group by means of an indicator variable improved the correlation (s = 0.533, R = 0.925), and omitting of 2-F, 2-Cl, 2-Br, and 2-I substituents gave a regression without deviating points (s = 0.352, R = 0.968). In the experiment, the researchers used many compounds, for example, 2-Chloro-6-nitrobenzoic acid (cas: 5344-49-0SDS of cas: 5344-49-0).
2-Chloro-6-nitrobenzoic acid (cas: 5344-49-0) belongs to organic chlorides. Organochlorines are organic compounds having multiple chlorine atoms. They were the first synthetic pesticides that were used in agriculture. They are resistant to most microbial and chemical degradations. Aliphatic organochlorides are often alkylating agents as chlorine can act as a leaving group, which can result in cellular damage.SDS of cas: 5344-49-0
Referemce:
Chloride – Wikipedia,
Chlorides – an overview | ScienceDirect Topics