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Reactions of Aldehydes and Ketones: Baeyer–Villiger Oxidation

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Baeyer–Villiger oxidation converts aldehydes to carboxylic acids and ketones to esters. The reaction uses peroxy acids or peracids and is often catalyzed by acid. The reaction is named after its pioneers, Adolf von Baeyer and Victor Villiger. The reaction is achieved by a wide range of peracids such as m-chloroperoxybenzoic acid (mCPBA), perbenzoic acid (C6H5COOOH), peracetic acid (CH3COOOH), hydrogen peroxide (H2O2), and tert-butyl hydroperoxide (t-BuOOH).
The carbonyl center is activated by...

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The reaction involving bases like EtO− whose conjugate acid EtOH (pKa = 15.9) is stronger than the ketone (pKa = 19.2) results in an equilibrium mixture with higher ketone concentration. As a consequence, side reactions...

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One of the critical aspects of the E1 reaction mechanism, as also observed in E2, is the regiochemistry, with multiple regioisomers obtained as products. In the example discussed, the presence of water as a weak base favors elimination over substitution to generate two alkenes. Given that alkenes’ stability increases with the number of alkyl groups across the double bond, typically, E1 reactions lead to the Zaitsev product, for this is more substituted and stable than the Hofmann product.

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Reduction is a simple strategy to convert a carbonyl group to a hydroxyl group. The three major pathways to reduce carbonyls to alcohols are catalytic hydrogenation, hydride reduction, and borane reduction.
Catalytic hydrogenation is similar to the reduction of an alkene or alkyne by adding H2 across the pi bond in the presence of transition metal catalysts like Raney Ni, Pd–C, Pt, or Ru. Aldehydes and ketones can be reduced by this method, often under mild to moderate heat (25–100°C) and...

Protecting Groups for Aldehydes and Ketones: Introduction

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Updated: Jul 16, 2026

Unraveling Entropic Rate Acceleration Induced by Solvent Dynamics in Membrane Enzymes

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Published on: January 16, 2016

Substrate-Specific Differences in Catalytic Strategy and Activity across Ketol-Acid Reductoisomerase Variants.

Elijah Karvelis^1,2, Bruce Tidor^1,2,3

¹Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.

The Journal of Physical Chemistry. B

|July 15, 2026

Summary

Enzyme mutations designed to boost activity on one substrate showed varied effects on another. Some KARI mutants enhanced catalysis for 2-aceto-2-hydroxybutyrate (AHB), while others decreased it, revealing complex substrate-specific mechanisms.

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Defining Substrate Specificities for Lipase and Phospholipase Candidates

Defining Substrate Specificities for Lipase and Phospholipase Candidates

Published on: November 23, 2016

Area of Science:

Enzyme kinetics and protein engineering.
Computational biophysics and molecular dynamics simulations.

Background:

Enzymes are crucial for catalysis, but understanding their mechanisms and re-engineering them for improved efficiency remains challenging.
Previous work identified KARI mutants with enhanced activity on 2-acetolactate (ACL), a substrate for valine and leucine synthesis.

Purpose of the Study:

To investigate the impact of previously designed KARI mutations on the catalysis of a second native substrate, 2-aceto-2-hydroxybutyrate (AHB).
To explore the structural and dynamic mechanisms underlying the substrate-specific effects of these mutations on enzyme activity.

Main Methods:

Utilized transition interface sampling (TIS), a computational statistical mechanical method, to simulate reaction kinetics.
Computed reaction rate constants for wild-type (WT) and mutant KARI enzymes with AHB as the substrate.

Main Results:

Mutants selected for improved 2-acetolactate (ACL) catalysis exhibited diverse effects on 2-aceto-2-hydroxybutyrate (AHB) catalysis, with rate constants spanning over seven orders of magnitude.
Analysis indicated that structural mechanisms enhancing ACL catalysis did not universally transfer to improve AHB catalysis.
Unique conformational changes were identified in two mutants with significantly reduced AHB catalytic efficiency compared to WT.

Conclusions:

Enzyme mutations can have complex, substrate-dependent effects on catalytic efficiency.
The transferability of engineered catalytic mechanisms is limited, highlighting the need for substrate-specific design.
Understanding substrate-specific conformational dynamics is crucial for predicting and optimizing enzyme performance.