Tetrabutylammonium dichromate

Bis-(tetrabutylammonium) dichromate [56660-19-6] M 700.9, m 139-142°. Wash with water and dry in a vacuum. Crystallises from hexane (m 79-80°). [Synth Commun 10 75 1980.] (Possible CARCINOGEN). 

Bis(tetrabutylammonium) Dichromate 2.7.6J Tetrakis(pyrUline)silver Dichromate... 

Bis(tetrabutylammonium) dichromate is a neutral oxidant which at reflux in dichloromethane acts as a selective oxidant for allylic and benzylic alcohols.Only 10% of oxidation products are obtained after treatment of n-decanol with bis(tetrabutylammonium) dichromate for 24 h. 

In this oxidation, tetrabutylammonium bisulfate works as a phase transfer catalyst in a two phase system, consisting of water and dichloromethane, in which chromic acid is formed by the action of sulfuric acid on potassium dichromate. 

PTC methods for the oxidation of water-insoluble acid-sensitive alcohols have been described which use an aqueous sulphuric acid solution of potassium dichromate, dichloromethane and catalytic amounts of tetrabutylammonium hydrogen sulphate.103... 

Chemicals AIBN CAN DIBAL DMAP DMSO HMPA LAH LDA mCPBA NBS NCS or PCC PDC Py TBAF TEMPO a.a -azobislisobutyronitrile) cerium(IV) ammonium nitrate diisobutylaluminium hydride 4-(dimethylamino)pyridine dimethyl sulfoxide hexamethylphosphoramide lithium aluminum hydride lithium diisopropylamide m-chloroperoxybenzoic acid A-bromosuccinimide A-chlorosuccinimide superoxide anion radical pyridinium chlorochromate pyridinium dichromate pyridine tetrabutylammonium fluoride 2,2,6,6-tetramethyl-l-piperidinyloxy free radical... 

Bll((etra-R-bntylaniinoiuiiiii) dichromate, [(C4H9)4N]2Cr207. Mol. wt. 700.91, orange crystals, m.p. 129-133°. This solubilized form of potassium dichromate is prepared by treatment of potassium chromate with tetrabutylammonium hydrogen ulfate. 

Sodium dichromate, Na2Cr207, is applied not only in solutions in sulfuric acid but also in solutions in perchloric acid [620, 621], acetic acid [622, 623, 624, 625, 626, 627, 628], benzene, and dimethyl sulfoxide [629], In the presence of tetrabutylammonium bisulfate, dichloromethane, used as a water-insoluble solvent, extracts the product from the aqueous phase (phase transfer) [630]. 

A modern version of dichromate oxidation in aqueous media is a phase-transfer reaction carried out in a two-phase system. Alkaline di-chromate is converted into tetraalkylammonium dichromate, which is soluble in organic solvents such as dichloromethane, chloroform, or benzene ( orange benzene ). The treatment of alcohols with a solution of potassium dichromate in acetic acid in the presence of Adogen 464 (Aldrich s trade name for methyltrialkyl [Cg-Cio] ammonium chloride) and benzene gives aldehydes at 55 °C [651. Similar results are obtained with a chloroform solution of tetrabutylammonium chromate at 60 °C [618]. ... 

Oxidations with dichromates can be accomplished in nonaqueous media or in a two-phase system by using phase-transfer reagents. The addition of 1-phenylethanol to a slurry of potassium dichromate and Adogen 464 (methyltrialkylammonium chloride) in benzene heated at 55 °C for 15 h results in an 80% yield of acetophenone. However, 2-octanol gives only a 33% yield of the ketone after being heated at 55 °C for 24 h [651]. Other solvents suitable for the reaction are dichloromethane, chloroform, and carbon tetrachloride, but not hexane [651], Better results are obtained when the alcohol is shaken for 1 min at room temperature with a mixture of a catalytic amount (10%) of tetrabutylammonium bisulfate and sodium dichromate in dichloromethane and aqueous 3 M sulfuric acid [630. ... 

The silylated methyl ester was then a-methylated with lithium diisopropylamide and methyl iodide in tetrahydrofuran. Reduction of methyl 10-( erl-butyldimethylsilyloxy)-2-methyldecanoate with DIBAL in ether at -78°C afforded the corresponding aldehyde. The 10- tert-butyldimethylsilyloxy)-2-methyldecanal was subsequently coupled in a Wittig reaction with 1-hexyltriphenylphosphonium bromide and n-butyllithium affording (Z)- and ( )-1 -(teri-butyldimethylsilyloxy)-9-methyl-10-hexadecene in a 9 1 ratio, respectively. Deprotection with tetrabutylammonium fluroride (TBAF) in tetrahydrofuran and final oxidation with pyridinium dichromate (PDC) in dimethylformamide resulted in a 9 1 mixture of (Z)- and ( )-9-methyl-10-hexadecenoic acid as shown in Fig. (7). As was also the case with acid 6, the stereochemistry at C-9 in 7 is not known. The key step in the synthesis of the allylic methyl group was a-methylation of a methyl ester, followed by reduction to the corresponding aldehyde, which was used in the subsequent Wittig reaction. 

Borabicyclo[3.3. l]nonane Butylated hydroxytoluene 3,4-Dihydro-2//-pyran Diisobutylaluminum hydride V,jV-Dimethylformamide Dimethyl sulfoxide Hexamethylphosphoric triamide Lithium aluminum hydride Lithium diisopropylamide Minimum inhibitory concentration Pyridinium chlorochromate Pyridinium dichromate S-adenosylmethionine Tetrabutylammonium fluoride tert-Butyldimethylsilyl tert-Butyldimethylsilyl chloride Tetrahydrofuran Trimethylsilyl cyanide... 

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