Additivity of substituent effects in meta- and para-substituted benzoic acids

Kalfus, K.; Kroupa, Jiří; Večeřa, M.; Exner, Otto

doi:10.1135/cccc19753009

Cited by 16 publications

(6 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Unlike the case with the Bolton-Hunter reagent, this p-hydroxyl group enhances the resonance stabilization of the ground state, thereby reducing the rate of nucleophilic attack at the carboxyl carbon ( 22). This ground-state stabilization is also reflected by the fact that HIBA is a weaker acid than IBA (23).…”

Section: Resultsmentioning

confidence: 99%

“…Tissue Distribution Measurements. These studies were performed in paired-label format in normal male BALB/c mice weighing [22][23][24][25][26][27][28][29][30] g. Groups of five or six animals were injected in the tail vein with a mixture of both preparations and sacrificed by ether overdose at selected time points. Tissues of interest were removed, washed with saline, and weighed.…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Radioiodination of proteins using N-succinimidyl 4-hydroxy-3-iodobenzoate

Vaidyanathan¹,

Affleck²,

Zalutsky³

1993

Bioconjugate Chem.

View full text Add to dashboard Cite

N-Succinimidyl 4-hydroxy-3-[131I]iodobenzoate ([131I]SHIB) was synthesized from 4-hydroxybenzoic acid in two steps. The overall radiochemical yield was 40-56%. A monoclonal antibody (mAb) was labeled in 10-15% yield by reaction with [131I]SHIB. The specific binding of [131I]SHIB mAb to tumor homogenates in vivo was 78 +/- 3%, compared to 84 +/- 3% for the same mAb labeled using N-succinimidyl 3-[125I]iodobenzoate ([125I]SIB). Paired-label studies in normal mice demonstrated similar tissue distributions of 131I and 125I except in thyroid. In thyroid, uptake of the two isotopes was similar on day 1; however, 131I levels increased gradually to 2-3 times those of 125I by day 6. Our results indicate that loss of label in vivo from mAbs labeled using SHIB is somewhat higher than seen with SIB but significantly lower than that observed when direct iodination methods are used.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Radioiodination of proteins using N-succinimidyl 4-hydroxy-3-iodobenzoate

Vaidyanathan¹,

Affleck²,

Zalutsky³

1993

Bioconjugate Chem.

View full text Add to dashboard Cite

show abstract

“…Similarly, for the case of 3,4,5-trichlorobenzoic acid,3a the value of σ p for Cl (0.23) would be added to twice the value for σ m (0.37) to obtain ∑σ = 0.97. The additivity rule naturally works well only when the groups are not interacting significantly. , Since the σ m and σ p values are obtained from the ionization constants of substituted benzoic acids, the additivity rule has serious drawbacks when applied to the multiply substituted benzene derivatives. For instance, in the above examples, the electronic effects due to the ortho arrangement of two amino groups or one meta and two ortho combinations resulting from the 3,4,5 arrangements of chlorines are completely neglected in the ∑σ values.…”

Section: Introductionmentioning

confidence: 99%

A Novel Electrostatic Approach to Substituent Constants: Doubly Substituted Benzenes

1998

View full text Add to dashboard Cite

The most negative-valued molecular electrostatic potential (MESP) minimum (V min) observed over the benzene ring is proposed as a sensitive quantity for the analysis of the electronic perturbations due to the substituents attached to it. MESP topography of 45 doubly substituted benzenes is mapped at HF/6-31G** level for an appraisal of this proposition. The V min values are seen to clearly reflect the changes due to the different orientations (para, meta, and ortho) and conformations of the substituents and different mechanisms of electron donation or withdrawal. Good linear correlations are obtained with V min and the experimentally determined σ values of the ortho- and meta-disubstituted benzenes. New quantities, D p, D m, and D o, introduced in this work as the substituent pair-constants respectively for the para, meta, and ortho arrangements, provide a quantitative measure of the simultaneous effect of two substituents over the aromatic nucleus. The predictive power of these quantities is checked in the case of some triply substituted benzenes using an equation V min = V ben + ∑ΔV min(mono) − ∑D p − ∑D m − ∑D o where V ben is the MESP minimum of benzene and ΔV min(mono) is the difference between the monosubstituted benzene V min and V ben. These predicted values are in fairly good agreement with the MESP values obtained at HF/6-31G** level.

show abstract

“…3), the values have been shown to be mostly equal to the sum of the values of individual substituents [33,34]. The slope , termed`reaction constant', is a function of the reaction series studied.…”

Section: Resultsmentioning

confidence: 99%

Untitled

González‐Mancebo¹,

Lacadena²,

García-Alonso

et al. 2002

Monatshefte fuer Chemie

View full text Add to dashboard Cite

Nitrosation reactions of phenol, o-cresol, 2,6-dimethylphenol, o-tert-butylphenol, 2-hydroxyacetophenone, and 2-allylphenol in water and water=acetonitrile were studied. Kinetic monitoring of the reactions was accomplished by spectrophotometric analysis of the nitrosated products at 345 nm. The dominant reaction was C-nitrosation via a mechanism consisting of an attack on the nitrosatable substrate by NO =NO 2 H 2 followed by a slow proton transfer. The values of the rate constants of phenolic C-nitrosation were increased by electron donating substituents, and a good Hammett correlation was observed with À6.1. The results also revealed the strong effect of pH and the permitivity of the reaction medium on the rate constant, whose maximum values were observed for pH % 3, decreasing strongly for higher pH values. The study in water=acetonitrile with up to 25% acetonitrile showed that it is possible to inhibit the reaction strongly by increasing the percentage of the organic component. The conclusions drawn show that (i) it is possible to predict the rate of nitrosation of phenolics as a function of the meta-substituents on the phenol ring and (ii) the nitrosation of phenolics can be strongly inhibited by increasing the pH of the reaction medium as well as by lowering its dielectric constant.

show abstract

Additivity of substituent effects in meta- and para-substituted benzoic acids

Cited by 16 publications

References 0 publications

Radioiodination of proteins using N-succinimidyl 4-hydroxy-3-iodobenzoate

Radioiodination of proteins using N-succinimidyl 4-hydroxy-3-iodobenzoate

A Novel Electrostatic Approach to Substituent Constants: Doubly Substituted Benzenes

Untitled

Contact Info

Product

Resources

About