Amberlyst A-26 resin

Alkylation of the thioacetate anion using Amberlyst A-26 resin... 

The polymer-supported hydridoiron tetracarbonyl (33 mmol) is prepared by the addition ofFe(CO)5(6.46g, 33 mmol) to KOH (5.6 g, 0.1 mol) in aqueous EtOH (1 1 v/v, 100 ml) under N2. The mixture is heated with stirring under reflux for 2 h and Amberlyst A-26 resin (24 g) is then added and the mixture is stirred for a further 15 min. The resin is collected, washed with degassed H20 (to neutrality), MeOH and Et20, dried at room temperature under a flow of N2, and used immediately. The haloalkane (11 mmol) in THF (50 ml) is added to the resin and the mixture is stirred under reflux for ca. 4 h. When GLC analysis shows the reaction to be complete, the resin is removed by filtration, and the filtrate evaporated under reduced pressure to give the aliphatic aldehyde. 

The Amberlyst A-26 resin consists of a complex hydrocarbon network with cationic ammonium ion appendages that serve as counterions to the anionic chromium oxidant, HCr04". Heating the insoluble polymeric reagent with an alcohol results in oxidation to a carbonyl compound, with formation of an insoluble Cr by-product. Not only can the metal by-product be removed by filtration without added solvent, it can also be regenerated and reused in a subsequent reaction. 

With Amberlyst A-26 resin-HCr04, 1 ° alcohols are oxidized to aldehydes and 2° alcohols are oxidized to ketones. 

ProblGin 12.26 What carbonyl compound is formed when each alcohol is treated with Amberlyst A-26 resin-HCr04 ... 

Oxidation of a 1 alcohol with PCC or Amberlyst A-26 resin-HCr04" stops at the aldehyde stage. Only one C - H bond is replaced by a C-0 bond. 

Because a 2° alcohol has only one C—H bond on the carbon bearing the OH group, all Cr reagents—PCC, C1O3, Na2Cr207, KgCrgO/, or HCr04 (Amberlyst A-26 resin)—oxidize a 2° alcohol to a ketone. 

Oxidation of a 1° alcohol with HCr04 , Amberlyst A-26 resin (12.13)... 

Furthermore, this ion-exchange strategy has been extended to a Dieckmann condensation starting from substituted anthranilic acids 42 [43]. Employing Amberlyst A-26 resin (OH" form) both as base and as purification sorbent, the authors synthesized a library of 4-hydroxy-quinolin-2(lH)-ones 43 (Scheme 14). 

Nitrates have been formed by reaction of tetra-n-butylammonium nitrate or the nitrate form of Amberlyst A-26 resin with various sulphonate esters. The former report also documented... 

INSTRUCTOR PREPARATION. Prepare the CrOs resin by adding 35 g of Amberlyst A-26 resin to a solution of 15 g of CrOs in 100 mL of water. Stir the mixture for 30 min at room temperature. Then collect the resin by vacuum filtration using a Buchner funnel and successively rinse it with water and acetone. Partially dry the material on the Buchner funnel by drawing air through the resin under vacuum for 1 h. Allow it to air-dry overnight. 

INSTRUCTOR PREPARATION. The CrOg resin is prepared by adding 35 g of Amberlyst A-26 resin to a solution of 15 g ofCrOs in 100 mL of water. Stir the mixture... 

Reagents CrOj-HMPA CrOj-Amberlyst A 26 resin DMSO TFAA NaOCl-BuJN HSO ... 

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