Reduction reactions in Organic Chemistry
NaNH2 is a strong base and excellent nucleophile. It’s used for deprotonation of weak acids and also for elimination reactions. Similar to: LDA ( lithium diisopropylamide ). The bases LiNH2 and KNH2 essentially similar. As a strong base, NaNH2 will deprotonate alkynes, alcohols, and a host of other functional groups with acidic protons such as esters and ketones. It is also a very strong nucleophile. One common application of NaNH2 is in the deprotonation of alkynes to give so-called “acetylide” ions. These ions are excellent nucleophiles and can go on to react with carbonyls in addition reactions.
A second application of NaNH2 is in the formation of alkynes from halogens. Treatment of either geminal dihalides (i.e. – two halogens on one carbon) or vicinal dihalides (halogens on adjacent carbons) with NaNH2 (2 equiv) will result in the formation of alkynes. So this is reducing property.
Since vicinal dihalides are easily made by the reaction of alkenes with halogens such as Br2 or I2, this is a useful way of converting alkenes to alkynes.
Deprotonation of functional groups such as OH and even alkyne C-H should hopefully be straightforward, but the use of bases to make alkenes may require some explanation. This is what is known as an elimination reaction, in that the elements H and Br (in this example) are removed in order to form the alkene. Specifically, this is an example of an E2 reaction.
Deprotonation of functional groups such as OH and even alkyne C-H should hopefully be straightforward, but the use of bases to make alkenes may require some explanation. This is what is known as an elimination reaction, in that the elements H and Br (in this example) are removed in order to form the alkene. Specifically, this is an example of an E2 reaction.
Since the alkene still has a halide attached, this too can be removed to generate a second double bond (π bond). This is another example of the E2 in that the hydrogen has to be anti to the bromine that is eliminated, but is unusual in that it is an sp2 hydrogen that is affected here:
NaNH2 can replace Chlorine
Furthermore, since NaNH2 is a strong base, it has the significant disadvantage of promoting side reactions from elimination (this can occur when attempting an SN2 with NaNH2 as the nucleophile, for example). Therefore, it is generally wise to avoid using NaNH2 as a nucleophile in organic synthesis. Sodium azide (followed by reduction) is the usual substitute.
NaNH2 acts as reducing agent
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