2023年1月23日 · One such modification is to conduct the substitution reaction in a strong acid, converting –OH to –OH 2(+). Because the hydronium ion (H 3 O (+)) is a much stronger acid than water, its conjugate base (H 2 O) is a better leaving group than hydroxide ion.

OH R NR' PCl 5 O - Schmidt rearrangement R R' O HN 3 H+ R NR' O - others OTf O NR 2 CO, DMF Pd(0), R 2NH TL 1985, 26, 1109 OTHP O O PhCH 2NH 2 AlMe 3 OTHP OH N H Ph O TL 1977, 4171-Weinreb amide Tetrahedron Lett. 1981, 22, 3815 R OR' O H 3CNH(OCH 3) •HCl AlMe 3 R N O OCH 3 CH 3 DIBAL R 1-M R H O R R 1 O. Author: CJ Rizzo

2023年1月23日 · In general, the hydroxyl group proved to be a poor leaving group, and virtually all alcohol reactions in which it was lost involved a prior conversion of –OH to a better leaving group. This has proven to be true for the carboxylic acids as well. Four examples of these hydroxyl substitution reactions are presented by the following equations.

OCH3 group is more electron withdrawing (i.e, shows more -I effect) than the OH group. WHY? The reason is that, there are two lone pairs of oxygen. Oxygen has a smaller size, so in case of OCH 3, the methyl group is close to the lone pair electrons, which leads to Steric repulsion.

2024年1月27日 · In some books it is written that +M (mesomeric effect) effect of OH is less than that of OR. The reason they give is inductive effect of R (group) which sounds plausible. But in some places it is

2020年4月22日 · An Arrhenius base is a substance that dissociates in water to form hydroxide (OH−) ions; that is, a base increases the concentration of OH− ions in an aqueous solution. So a stronger Arrhenius base more easily dissociates to form OH- ions.

2011年4月6日 · With your question, -OCH3 is a larger molecule (more electrons from the methyl donating group) and will more easily donate electrons (think kinetics), but it is also a weaker base than -OH. H isn't electron donating, and the methyl electron donating group increases the strength of the nucleophile.

2021年7月31日 · Several important chemical reactions of alcohols involve only the oxygen-hydrogen bond and leave the carbon-oxygen bond intact. An important example is salt formation with acids and bases. Alcohols, like water, are both weak bases and weak acids.

2018年10月20日 · Facts I know: 1) More the electron density in benzene ring, the faster the reaction. 2) Lone pair on -OCH3 group undergoes resonance and makes ortho-para positions electron rich, and so does -CH3 by hyperconjugation. 3) -OCH3 group shows -I (electron withdrawing) and -CH3 shows +I (electron releasing).

2022年8月30日 · Why is OH more activating than OCH3? OH (hydroxy) has a better +R effect than OCH3 because The -CH3 group in -OCH3 causes steric repulsions with lone pairs, increasing bond angles. Due to which it make -O- atom of -OCH3 more electro-negative and thus affecting donor tendency.