Organic reduction in the context of "Carbonyl reduction"

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⭐ Core Definition: Organic reduction

Organic reductions or organic oxidations or organic redox reactions are redox reactions that take place with organic compounds. In organic chemistry oxidations and reductions are different from ordinary redox reactions, because many reactions carry the name but do not actually involve electron transfer. Instead the relevant criterion for organic oxidation is gain of oxygen and/or loss of hydrogen. Simple functional groups can be arranged in order of increasing oxidation state. The oxidation numbers are only an approximation:

When methane is oxidized to carbon dioxide its oxidation number changes from −4 to +4. Classical reductions include alkene reduction to alkanes and classical oxidations include oxidation of alcohols to aldehydes. In oxidations electrons are removed and the electron density of a molecule is reduced. In reductions electron density increases when electrons are added to the molecule. This terminology is always centered on the organic compound. For example, it is usual to refer to the reduction of a ketone by lithium aluminium hydride, but not to the oxidation of lithium aluminium hydride by a ketone. Many oxidations involve removal of hydrogen atoms from the organic molecule, and reduction adds hydrogens to an organic molecule.

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👉 Organic reduction in the context of Carbonyl reduction

In organic chemistry, carbonyl reduction is the conversion of any carbonyl group, usually to an alcohol. It is a common transformation that is practiced in many ways. Ketones, aldehydes, carboxylic acids, esters, amides, and acid halides - some of the most pervasive functional groups, -comprise carbonyl compounds. Carboxylic acids, esters, and acid halides can be reduced to either aldehydes or a step further to primary alcohols, depending on the strength of the reducing agent. Aldehydes and ketones can be reduced respectively to primary and secondary alcohols. In deoxygenation, the alcohol group can be further reduced and removed altogether by replacement with hydrogen.

Two broad strategies exist for carbonyl reduction. One method, which is favored in industry, uses hydrogen as the reductant. This approach is called hydrogenation and requires metal catalysts. The other broad approach employs stoichiometric reagents that deliver H and H separately. This article focuses on the use of these reagents. Prominent among these reagents are the alkali metal salts of borohydrides and aluminium hydrides.

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Organic reduction in the context of Semisynthesis

Semisynthesis, or partial chemical synthesis, is a type of chemical synthesis that uses chemical compounds isolated from natural sources (such as microbial cell cultures or plant material) as the starting materials to produce novel compounds with distinct chemical and medicinal properties. The novel compounds generally have a high molecular weight or a complex molecular structure, more so than those produced by total synthesis from simple starting materials. Semisynthesis is a means of preparing many medicines more cheaply than by total synthesis since fewer chemical steps are necessary.

Drugs derived from natural sources are commonly produced either by isolation from their natural source or, as described here, through semisynthesis of an isolated agent. From the perspective of chemical synthesis, living organisms act as highly efficient chemical factories, capable of producing structurally complex compounds through biosynthesis. In contrast, engineered chemical synthesis, although powerful, tends to be simpler and less chemically diverse than the complex biosynthetic pathways essential to life.

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Organic reduction in the context of Birch reduction

The Birch reduction or Metal-Ammonia reduction is an organic reaction that is used to convert arenes to 1,4-cyclohexadienes. The reaction is named after the Australian chemist Arthur Birch and involves the organic reduction of aromatic rings in an amine solvent (traditionally liquid ammonia) with an alkali metal (traditionally sodium) and a proton source (traditionally an alcohol). Unlike catalytic hydrogenation, Birch reduction does not reduce the aromatic ring all the way to a cyclohexane.

Another example is the reduction of naphthalene in ammonia and diethyl ether:

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