Potassium hexamethylphosphoramid

Potassium/hexamethylphosphoramide Reductive replacement of cyano groups by hydrogen s. 27, 87... 

Using hexamethylphosphoramide as the solvent, only the second reaction occurs. Disilane also reacts with potassium in 1,2-dimethoxyethane to form KS1H3, although S1H4 and nonvolatile polysHanes are also produced (28,31). Pure crystalline KSiH prepared from SiH and potassium in 1,2-dimethoxyethane has been obtained by slow evaporation of the solvent. WhenHquid ammonia is used as the solvent, only a small fraction of SiH is converted into metal salt most of the SiH undergoes ammonolysis (32). 

Only 22-45% yields of m-fluoronitrobenzene are obtained from the fluoro-denitration of m dinitrobenzene by potassium fluoride in Af-methyl-2-pyrrolidone or hexamethylphosphoramide, along with significant amounts of 3,3 dinitro-diphenyl ether [107, 108, 109] (equation 32)... 

Diphenylmethane reacts with dioxygen in the presence of potassium 1,1-dimethylethoxide in various solvents (dimethylformamide [DMF], hexamethylphosphoramide [HMPA], pyridine) to produce nearly 100% yields of benzophenone [284]. The adduct of benzophenone with dimethylsulfoxide (DMSO) [l,l-diphenyl-2-(methylsulfinyl)ethanol] is formed as the final product of the reaction. The stoichiometry of the reaction and the initial rate depends on the solvent (conditions 300 K, [Ph2CH2] = 0.1mol L [Me3COK] = 0.2mol L 1,p02 = 97kPa). 

Hexafluorothioacetone, 50, 83 Hexamethylbicyclo[1.1.0]butane, from 1,3-dibromohexamethyl-cyclo butane and sodium-potassium alloy, 51, 58 Hexamethylphosphoramide, 50,... 

The synthesis of 168 has also been completed by using other reaction conditions (Scheme 22). 6,7-Dimethoxyisoquinoline (162) was reacted with potassium cyanide and 2-chloromethylbenzoyl chloride in the presence of a catalytic amount of benzyltriethylammonium chloride, resulting in 164 which on treatment with lithium diisopropylamide in hexamethylphosphoramide-tetrahydro-furan solvent mixture afforded the cyclized product 168 in high yield (40). 

Synthesis of 2,3-dihydro-l,4-dithiin 11 was accomplished from l,3-dithiol-2-one 247 in the presence of dibro-moethane and potassium hydroxide <1998JOG3952>, while reaction of 2,3-dichloro-l,4-dioxane with powdered Zn in hexamethylphosphoramide (HMPA) was used for the synthesis of 1,4-dioxene 10 <1998JPP10067773>. To obtain substituted 1,4-oxathianes, the hydrogenation of the corresponding partially saturated compounds has been employed <2001J(P1)2604>. 

Dinitrobenzene (5) has been converted to l-fluoro-3-nitrobenzene (6) with potassium fluoride in jV-methyl-2-pyrrolidone. Hexamethylphosphoramide can also be used as a solvent for this displacement reaction. Besides 5 some heterocyclic nitro compounds 7,9 were also converted to their respective fluoro analogs 8 and 10 by treating with potassium fluoride. 

AD-mix-P 9-BBN Bn Boc Bz BOM CDI m-CPBA CSA Cy DBU DDQ DEAD DIAD DIBAL-H DIPT DME DMF DMAP DMSO EDC HMPA HOBT KHMDS LDA MEM MOM MoOPH NaHMDS NBS NMM NMO Piv PMB Reagent for Sharpless asymmetric dihydroxylation 9-Borabicyclo[3.3.1 ]nonyl Benzyl t-Butoxy carbonyl Benzoyl B enzyloxy methyl Carbonyldiimidazole m-Chloroperoxybenzoic acid Camphorsulfonic acid Cyclohexyl 1,8 -Diazabicy clo[5.4.0] undec-7-ene 2,3 -Dichloro-5,6-dicyano-p-benzoquinone Diethyl azodicarboxylate Diisopropyl azodicarboxylate Diisobutylaluminum hydride Diisopropyl tartrate Dimethoxyethane A,N-Dimethylformamide 4-Dimethylaminopyridine Dimethyl sulfoxide N-(3-Dimethylaminopropyl)-A -ethylcarbodiimide Hexamethylphosphoramide 1 -Hydroxybenzotriazole Potassium hexamethyldisilazane Lithium diisopropylamide Methoxyethoxymethyl Methoxymethyl Oxidodiperoxymolybdenum(pyridine)(hexamethylphophoramide) Sodium hexamethyldisilazane N - Bromosuccinimide A-Methylmorpholine A-Methylmorpholine A-oxide Pivaloyl /j-Methoxybenzyl... 

A powerful oxidizer. Explosive reaction with acetaldehyde, acetic acid + heat, acetic anhydride + heat, benzaldehyde, benzene, benzylthylaniUne, butyraldehyde, 1,3-dimethylhexahydropyrimidone, diethyl ether, ethylacetate, isopropylacetate, methyl dioxane, pelargonic acid, pentyl acetate, phosphoms + heat, propionaldehyde, and other organic materials or solvents. Forms a friction- and heat-sensitive explosive mixture with potassium hexacyanoferrate. Ignites on contact with alcohols, acetic anhydride + tetrahydronaphthalene, acetone, butanol, chromium(II) sulfide, cyclohexanol, dimethyl formamide, ethanol, ethylene glycol, methanol, 2-propanol, pyridine. Violent reaction with acetic anhydride + 3-methylphenol (above 75°C), acetylene, bromine pentafluoride, glycerol, hexamethylphosphoramide, peroxyformic acid, selenium, sodium amide. Incandescent reaction with alkali metals (e.g., sodium, potassium), ammonia, arsenic, butyric acid (above 100°C), chlorine trifluoride, hydrogen sulfide + heat, sodium + heat, and sulfur. Incompatible with N,N-dimethylformamide. 

The most commonly used procedure is that established by Wooster and extensively developed by Birch, i.e. the reduction of a solution of the substrate in a mixture of liquid ammonia with an alcohol (usually ethanol or r-butyl alcohol) and an inert cosolvent (e.g. diethyl ether, tetrahydrofuran) with an alkali metal (lithium, sodium or potassium). Low molecular weight amines have been utilized in place of the ammonia, although the procedure then leads to more extensive reduction. Hexamethylphosphoramide may also serve in place of the ammonia, but there is no apparent advantage to offset its higher cost, toxicity and carcinogenicity. Of rather more interest is the potential of electrochemical and photochemical approaches, which may give complementary outcomes. 

Metals commonly utilized include the alkali metals, mainly lithium, sodium and potassium, and also calcium, zinc, magnesium, tin and iron. Alkali metals and calcium have been used in liquid ammonia," in low molecular weight aliphatic amines," in hexamethylphosphoramide, in ether or in THF containing crown ethers, or in very dilute solutions in polyethers such as 1,2-dimethoxyethane (DME)." Reactions with metal solutions in liquid ammonia often use a cosolvent, such as ether, THF or DME, to increase solubility of the organic substrate in the reaction mixture. These same metals, as well as zinc and magnesium, have been used as suspensions in various solvents including ether, toluene, xylene, etc. 

Reaction of hydrosilanes with alkali metals is seldom employed for generating silylmetallic reagents, except for HjSiM (M = Na, K, Pb, Cs). The silylmetallics of K, Rb and Cs may be prepared and isolated from 1,2-dimethoxyethane (DME) in 7-28 days The reaction of SiH4 and potassium in hexamethylphosphoramide (HMPA) (a carcinogen) gives a high yield of KSiHj, and Na and SiH. react in DME. 

Phenyllithium, and 50% sodium hydroxide with a catalytic amount of TEBA chloride, or cetrimonium bromide have been used in a few instances, instead of sodium hydride, to generate the anion in alkylation reactions. A study comparing the use of lithium diisopropylamide in tetrahydrofuran/hexamethylphosphoramide, potassium hydroxide with benzene and dicyclohexyl-18-crown-6, and 50% sodium hydroxide with benzene or acetonitrile and cetrimonium bromide for alkylation concludes that the phase transfer procedure is advantageous. Triton B has sometimes been used as an alternative to aqueous hydroxide for the hydrolysis of 27 to 28, " particularly in cases where R = 2-nitrobenzyl. - - ... 

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