Examples of reduce in the following topics:
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- The following table summarizes the influence each of the reducing systems discussed above has on the different classes of carboxylic acid derivatives.
- Note that Lithium Aluminum Hydride (LiAlH4) is the strongest reducing agent listed, and it reduces all the substrates.
- They are reduced by all the reagents, but only a few of these provide synthetically useful transformations.
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- Carbon atoms colored blue are reduced, and those colored red are oxidized.
- In the addition of hydrogen both carbon atoms are reduced, and the overall reaction is termed a reduction.
- Addition of HBr reduces one of the double bond carbon atoms and oxidizes the other; consequently, there is no overall redox change in the substrate molecule.
- Thus, Grignard reagent formation from an alkyl halide reduces the substituted carbon atom.
- In the following equation and half-reactions the carbon atom (blue) is reduced and the magnesium (magenta) is oxidized.
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- Al–O(–)), and the resulting iminium double bond would then be reduced to an amine.
- The resulting nitrile intermediate is then reduced to a 1º-amine.
- Lithium aluminum hydride reduces nitriles to 1º-amines, as shown in the following equation.
- Second, NaBH4 is much less reactive than LAH, failing to reduce amides and acids (they form carboxylate salts) at all, and reducing esters very slowly.
- The reduced intermediates that lead to aldehydes are displayed in the second diagram below.
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- Standard reduction potentials provide a systematic measurement for different molecules' tendency to be reduced.
- Reduction potential (also known as redox potential, oxidation/reduction potential, or Eh) measures the tendency of a chemical species to acquire electrons and thereby be reduced.
- The more positive the potential, the greater the species' affinity for electrons, or the more the species tends to be reduced.
- In this galvanic cell, zinc reduces copper cations.
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- Hydrides are compounds in which one or more hydrogen anions have nucleophilic, reducing, or basic properties.
- A hydride is the anion of hydrogen (H−), and it can form compounds in which one or more hydrogen centers have nucleophilic, reducing, or basic properties.
- While hydrides traditionally react as Lewis bases or reducing agents by donating electrons, some metal hydrides behave as both acids and hydrogen-atom donors.
- Hydrides are commonly used as reducing agents, donating electrons in chemical reactions.
- Ionic hydrides are often used as heterogeneous bases and reducing reagents in organic synthesis.
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- This is related to how easily the oxidized species gives up electrons and how badly the reduced species wants to gain them.
- Since the standard electrode potentials are given in their ability to be reduced, the bigger the standard reduction potentials, the easier they are to be reduced; in other words, they are simply better oxidizing agents.
- F2 reduces easily and is therefore a good oxidizing agent.
- In contrast, Li(s) would rather undergo oxidation, so it is a good reducing agent.
- In the example of Zn2+, whose standard reduction potential is -0.76 V, it can be oxidized by any other electrode whose standard reduction potential is greater than -0.76 V and can be reduced by any electrode with standard reduction potential less than -0.76 V.
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- Electron addition to a functional group is by definition a reduction, and we noted earlier that alkynes are reduced by solutions of sodium in liquid ammonia to trans-alkenes.
- For practical purposes, we can consider such solutions to be a source of "free electrons" which may be used as powerful reducing agents.
- Returning to the reducing capability of the blue electron solutions, we can write a plausible mechanism for the reduction of alkynes to trans-alkenes, as shown below.
- Isolated carbon double-bonds are not reduced by sodium in liquid ammonia, confirming the electronegativity difference between sp and sp2 hybridized carbons.
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- Sodium borohydride will reduce only the imine and ketone.
- But what if a chemist's intention is to leave the carboxylic acid and ketone functionalities, while reducing the imine?
- Sodium cyanoborohydride is chemoselective enough to reduce only the imine.
- There is no reducing agent that would reduce the ester to an alcohol that would not also reduce the ketone.
- Once the ester is reduced, the acetal can be removed, thus yielding the original ketone functionality.
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- These compounds are easily reduced to their dihydroxybenzene analogs, and it is from these compounds that quinones are best prepared.
- Reducing agents other than stannous chloride (e.g.