Chemistry is the experimental and theoretical study of materials on their properties at both the macroscopic and microscopic levels.In a patent， Recommanded Product: 5-Methoxy-2-methyl-1H-indole, Which mentioned a new discovery about 1076-74-0
The SEAr substitutions of a number of 5-X-substituted indoles (1a-f), 5-X-substituted 2-methylindoles (1g-j) and N-methylindole (1k) by 4,6-dinitrobenzofuroxan (DNBF) have been kinetically studied in 70-30 (v/v) H2O-Me2SO, 50-50 (v/v) H2O-Me2SO, methanol and acetonitrile.The absence of a significant dependence of the rates of reactions on the hydrogen or deuterium labelling at C-3 of the indole ring indicates that electrophilic attack (k1DNBF) by DNBF at this position is the rate-limiting step of the substitutions.However, the k1DNBF rate constants are strongly sensitive to the solvent polarity, the observed reactivity sequence being 70-30 H2O-Me2SO > 50-50 H2O-Me2SO > methanol > acetonitrile.This trend is consistent with a highly dipolar transition state where the development of negative charge in the DNBF moiety is concomitant with that of a partial positive charge on the indole nitrogen.The finding of relatively large negative rho values (-3.85) for the Hammett plots log k1DNBF = f(?px supports this idea.An interesting result is that the effect of the X substituent on the rates (k1DNBF) is the same in the four solvents studied and does not depend upon the substitution at C-2 of the indole ring.However, the Broensted or Hammett lines for the 5-X-2-methylindoles are located about 1.5 log k unit below those for the 5-X-indoles in a given solvent, showing that the 2-methyl group causes significant steric hindrance to the approach of DNBF from the adiacent C-3 position.Rates of protiodetritiation of a large number of <3-3H>indoles have also been measured in aqueous solution.The data define a unique Broensted line (betalnH = 0.65), implying that the 2-substituents do not exert any steric effect on the rates of the exchange process and suggesting that the correlation can be used to estimate unknown pKa values of indoles with a free 3-position.Comparison of the rates of coupling of indoles with 4,6-dinitrobenzofuroxan with similar data for coupling of these heterocycles with p-nitrobenzenediazonium cation reveals that, despite its neutral character, DNBF is the most electrophilic species.DNBF also appears to be a much stronger electrophile than the proton.
Because enzymes can increase reaction rates by enormous factors and tend to be very specific, category: indole-building-block, typically producing only a single product in quantitative yield, they are the focus of active research.you can also check out more blogs about 1076-74-0
Reference：
Indole alkaloid derivatives as building blocks of natural products from Bacillus thuringiensis and Bacillus velezensis and their antibacterial and antifungal activity study,
Preparation of Indole Containing Building Blocks for the Regiospecific Construction of Indole Appended Pyrazoles and Pyrroles