Perkin reactions cesium acetate

The Perkin reaction is of importance for the iadustrial production of coumarin and a number of modifications have been studied to improve it, such as addition of a trace of iodine (46) addition of oxides or salts of metals such as iron, nickel, manganese, or cobalt (47) addition of catalytic amounts of pyridine (48) or piperidine (49) replacement of sodium acetate by potassium carbonate (50,51) or by cesium acetate (52) and use of alkaU metal biacetate... 

Recently, it has been reported that significantly higher yields are obtained and shorter reaction times required in the Perkin synthesis of cinnamic acids when sodium acetate is replaced by cesium acetate. ... 

It has been reported that microwave irradiation shortens the reaction time of the Perkin reaction by 60-fold over classical heating. Cesium salts (acetate, carbonate, fluoride) with a small amount of pyridine were found to be the best catalysts.12 Thus, p-hydroxybenzaldehyde (45) reacted with acetic anhydride using cesium acetate as a catalyst to provide the a, p-unsaturated acid 46 in 85% yield. 

The most important modification of the Perkin reaction was developed by Oglialoro using the sodium salt of acetic acid (e.g., phenylacetic acid, phenoxyacetic acid ) in condensation with acetic anhydride and an aldehyde (e.g., benzaldehyde, paraldehyde ). This type of reaction is referred to as the Perkin-Oglialoro reaction,Perkin-Oglialoro condensation, or Oglialoro modification. Other modifications include the use of different bases as the catalysts, (e.g., NaB(OMe)4-LiCl, CaH2, CsOAc, and CsF ), the use of microwave irradiation and cesium acetate or fluoride in combination with a small amount of pyridine as catalyst and the continuous distillation of acetic acid to enhance the conversion rate. ... 

Perkin Synthesis. This synthesis is a well-known organic reaction yielding cinnamic acid from an aromatic aldehyde and an anhydride. Commonly, sodium acetate has been used in the reaction as a base catalyst. However, significant increase in yield was found when cesium acetate was used instead of sodium acetate (eq 6). In fact, yields were shown to increase up to 10 times with certain aryl substrates when cesium acetate was substituted for sodium acetate. ... 

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See also in sourсe #XX -- [ , ]

See also in sourсe #XX -- [ ]

See also in sourсe #XX -- [ ]

See also in sourсe #XX -- [ ]

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