Editing Ester (section)

=== Reduction ===
Compared to ketones and aldehydes, esters are [[Carbonyl reduction#Trends in carbonyl reactivity|relatively resistant to reduction]]. The introduction of catalytic hydrogenation in the early part of the 20th century was a breakthrough; esters of fatty acids are hydrogenated to [[fatty alcohol]]s.
:{{chem2|RCO2R' + 2 H2 → RCH2OH + R'OH}}
A typical catalyst is [[copper chromite]]. Prior to the development of [[catalytic hydrogenation]], esters were reduced on a large scale using the [[Bouveault–Blanc reduction]]. This method, which is largely obsolete, uses sodium in the presence of proton sources.

Especially for fine chemical syntheses, [[lithium aluminium hydride]] is used to reduce esters to two primary alcohols. The related reagent [[sodium borohydride]] is slow in this reaction. [[DIBAH]] reduces esters to aldehydes.<ref>{{cite web | author=W. Reusch | title=Carboxyl Derivative Reactivity | url=http://www.cem.msu.edu/~reusch/VirtualText/crbacid2.htm#react2 | work=Virtual Textbook of Organic Chemistry | url-status=dead | archive-url=http://arquivo.pt/wayback/20160516073829/http://www.cem.msu.edu/~reusch/VirtualText/crbacid2.htm#react2 | archive-date=2016-05-16}}</ref>

Direct reduction to give the corresponding [[ether]] is difficult as the intermediate [[hemiacetal]] tends to decompose to give an alcohol and an aldehyde (which is rapidly reduced to give a second alcohol). The reaction can be achieved using [[triethylsilane]] with a variety of Lewis acids.<ref>{{cite journal|last1=Yato|first1=Michihisa|last2=Homma|first2=Koichi|last3=Ishida|first3=Akihiko|title=Reduction of carboxylic esters to ethers with triethyl silane in the combined use of titanium tetrachloride and trimethylsilyl trifluoromethanesulfonate|journal=Tetrahedron|date=June 2001|volume=57|issue=25|pages=5353–5359|doi=10.1016/S0040-4020(01)00420-3}}</ref><ref>{{cite journal|last1=Sakai|first1=Norio|last2=Moriya|first2=Toshimitsu|last3=Konakahara|first3=Takeo|title=An Efficient One-Pot Synthesis of Unsymmetrical Ethers: A Directly Reductive Deoxygenation of Esters Using an InBr3/Et3SiH Catalytic System|journal=The Journal of Organic Chemistry|date=July 2007|volume=72|issue=15|pages=5920–5922|doi=10.1021/jo070814z|pmid=17602594}}</ref>