A-Hydrogen of esters

The a hydrogens of esters are weakly acidic, and they can be deprotonated to give eno-... 

Solution The Claisen condensation takes advantage of the acidic a hydrogen of esters, 3 ketoesters and 3-di ... 

Sodium borohydride reduces esters but the reaction is too slow to be useful Hydrogenation of esters requires a special catalyst and extremely high pressures and tern peratures it is used m industrial settings but rarely m the laboratory... 

Alcohols are the most frequently formed products of ester hydrogenolysis. The hydrogenation of esters to alcohols is a reversible reaction with alcohol formation favored at high pressure, ester at low pressure (/). Copper chromite is usually the catalyst of choice. Details for the preparation of this catalyst (/7) and a detailed procedure for hydrogenation of ethyl adipate to hexamethylene glycol (/[Pg.80]

The hydrogenation of esters remains a challenge. Some recent progress has been reported by Teunissen and Elsevier [71, 72] where a mixture of Ru(acac)3 and MeC(CH2PPh2)3 was used to hydrogenate aromatic and aliphatic esters to the alcohols in MeOH at 100-120 °C with 85 bar H2. 

Hydrogenation of esters, with copper chromite and Raney nickel, 8, 1 Hydrohalogenation, 13, 4 Hydroxyaldehydes, aromatic, 28, 1 a-Hydroxyalkylation of activated olefins, 51, 2... 

Bufotenidine or Cinobufagine This is the quaternary amine internal salt, 5-hydroxy-N,N,N-trimethyltryptammonium salt. It also is frequently found as a hydrogen sulfate ester, but this latter has no trivial name. Mention has been made of bufotenidine and its sulfate ester as a occasional companion of histamine analogues found in frog skins. See the appendix on histamines. 

Many important synthetic reactions in which C-C bonds are formed involve esters and are brought about by basic reagents. This is possible because the a hydrogens of an ester, such as RCH2C02C2H5, are weakly acidic, and a strong base, such as sodium ethoxide, can produce a significant concentration of the ester anion at equilibrium ... 

Linnartz, P., Bitter, S., Schalley, C.A Deslipping of ester rotaxanes a kooperative interplay of hydrogen bonding with rotational barriers, Eur. J. Org. Chem. (2003), 4819-4829. 

The rate law for the hydrogenation of esters to alcohols shows a dependence on the square of the hydrogen pressure. 

---