Catalyst, ammonium acetate piperidine

Carboxy-3,5-dichlorophenyl diazo-nium chloride, 31, 97 Catalyst, ammonium acetate, 31, 25, 27 copper chromite, 31, 32 ferric nitrate, hydrated, 31, 53 piperidine, 31, 35 piperidine acetate, 31, 57 Catechol, 33, 74... 

Cyclohexenylacetonitrile has been prepared by the decarboxylation of cyclohexylidenecyanoacetic acid 4-5 by the dehydration of 1-cyclohexenylacetamide 5 by the condensation of cyclohexanone and cyanoacetic acid in the presence of piperidine 6 by the condensation of cyclohexanone and ethyl cyano-acetate in the presence of sodium ethoxide 4-7 and by the condensation of cyclohexanone and cyanoacetic acid in the presence of ammonium acetate followed by decarboxylation.8 Ammonium acetate also has been used as a catalyst for the condensation of ketones with ethyl cyanoacetate.3-9... 

Catalyst, alumina, 34, 79, 35, 73 ammonium acetate, 31, 25, 27 boron tnfluonde etherate, 38, 26 copper chromite, 31, 32, 36, 12 cupric acetate monohydrate, 38, 14 cuprous oxide silver oxide, 36, 36, 37 ferric nitrate, hydrated, 31, 53 phosphoric acid, 38, 25 piperidine, 31, 35 piperidine acetate, 31, 57 Raney nickel, 36, 21, 38, 22 sulfuric acid, 34, 26 Catechol, 33, 74 Cetylmalonic acid, 34, 16 Cetylmalonic ester, 34,13 Chlorination, by sulfuryl chloride, 33, 45, 37, 8... 

Excellent yields of alkylidenemalononitriles, RR C = C(CN)j, are obtained by condensation of aldehydes and ketones with malononitrile. ° The catalysts are piperidine and benzylamine for aldehydes and ammonium acetate for ketones. 

Color reactions Boric acid (hydroxyquinones). Dimethylaminobenzaldehyde (pyrroles). Ferric chloride (enols, phenols). Haloform test. Phenylhydrazine (Porter-Silber reaction). Sulfoacetic acid (Liebermann-Burchard test). Tetranitromethane (unsaturation). Condensation catalysts /3-Alanine. Ammonium acetate (formate). Ammonium nitrate. Benzyltrimethylammonium chloride. Boric acid. Boron trilluoride. Calcium hydride. Cesium fluoride. Glycine. Ion-exchange resins. Lead oxide. Lithium amide. Mercuric cyanide. 3-Methyl-l-ethyl-2-phosphoiene-l-oxlde. 3-Methyl-1-phenyi-3-phoipholene-1-oxide. Oxalic acid. Perchloric acid. Piperidine. Potaiaium r-butoxIde. Potassium fluoride. Potassium... 

For the condensation of aldehydes with ethyl cyanoacetate Cope911 also used piperidine acetate and he treated ketones with this ester in the presence of ammonium acetate as catalyst he used benzene as solvent, removing the water produced through a water-separator. When this process is applied to acetone the benzene must be replaced by chloroform as entraining agent.912... 

A dual catalyst system piperidine-iodine was used in the synthesis of 3-substituted coumarins through a one-pot three-component reaction of salicylaldehyde derivatives, P-keto esters, and l-(2-aminophenyl)pyrrole in DMF at room temperature (14T2048) and through a four-component reaction of salicylaldehyde derivatives, P-keto esters, ammonium acetate, and isatoic anhydride in DMF at 60°C (Scheme 55) (14SL1596). 

In 2006, Fadda et al. reported the piperidine-catalyzed reaction of l-chloro-3,4-dihydronaphthalene-2-carboxalde-hyde 53 with pyrazole 52 and malonodinitrile 21 to provide an access to a chromeno[2,3-c]pyrazole 55 at high temperatures (Scheme 13.17) [28]. Exchange of the piperidine catalyst by an excess of ammonium acetate led to the formation of a pyrazolo[3,4-b]quinoline derivative 54 instead. 

These additions to the conjugated system are catalyzed by bases such as sodium hydroxide, sodium methoxide, tertiary amines, piperidine, and quaternary ammonium hydroxides. Cupric acetate catalyst is used in the conversion of acrolein to /S-methylmercaptopropionaldehyde, CHjSCHjCHjCHO (84%). The addition of mercaptans is analogous to the addition of alcohols to these systems (method 121). However, the thiol group is more active than the hydroxyl group, as is shown by... 

On the other hand the catalyst is of great importance primary, secondary or tertiary amines or their corresponding ammonium salts are usually used, but many other catalysts such as phase transfer catalysts, Lewis acids or potassium fluoride can also be applied. The most widely employed catalysts are pyridine, with or without added piperidine, and ammonium salts, such as ammonium or piperidinium acetate. Condensations that employ strong bases or preformed metal salts of the methylene component are not covered here since transformations under these conditions are not usually considered to be Knoevenagel reactions. 

---