Potassium amide-alumina

Potassium amide-alumina Prototropic rearrangement Ynamines from 2-acetyleneamines... 

Treatment of allylamines with potassium amide on alumina causes their isomerization to enamines in good yields (124b). When allylamines are heated to about 55° the same type of isomerization takes place (I24c). 

These catalysts require temperatures above 100° and usually 150-200° for reasonable rates. Alkylsodium compounds at their decomposition temperatures (50-90°) have also been used by Pines and Haag (9). Lithium reacted with ethylene diamine has also been reported by Reggel et al. (4) as a catalyst for this reaction. The homogeneous system thus formed seems to lower the temperature requirement to 100° (4), whereas the use of potassium amide in liquid ammonia requires 120° (S). Sodium reacted with ethylene diamine has been reported to be an ineffective catalyst (4)- The most active catalyst systems reported so far are high-surface alkali metals and activated-alumina supports. They are very effective at or near room temperature (10-12). 

More recently it has been reported that a dispersion of potassium amide on alumina is an active catalyst for the isomerization of N,V-dialkylprop-2-ynylamines into allenamines and ynamines [23]. For example, using potassium... 

An ab initio method has been employed to study the mechanism of the thermal isomerization of buta-1,2-diene to buta-1,3-diene. The results of the study have indicated619 that the transformation proceeds in a stepwise manner via a radical intermediate. Experimental free energies of activation for the bond shift in halocyclooctatetraenes have been reported and analyzed by using ab initio MO calculations.620 The isomerization of hexene using a dihydridorhodium complex in dimethyl sulfoxide has been reported,621 and it has been suggested622 that the Pd(II)-catalysed homogeneous isomerization of hexenes proceeds by way of zr-allylic intermediates. A study has been made623 of alkene isomerization catalysed by the rhodium /-phosphine-tin dichloride dimeric complex, and the double-bond isomerization of olefinic amines over potassium amide loaded on alumina has been described.624... 

Dehydrohalogenation Benzyltrimethylammonium mcsitoate. r-Butylamine. Calcium carbonate. j Uidine. Diazabicyclo[3.4.0]nonene-5. N.N-Dimethylaniline (see also Ethoxy-acetylene, preparation). N,N-Dimelhylformamide. Dimethyl sulfoxide-Potassium r-but-oxide. Dimethyl sulfoxide-Sodium bicarbonate. 2,4-Dinitrophenylhydrazine. Ethoxy-carbonylhydrazine. Ethyldicyclohexylamine. Ethyidiisopropylamine. Ion-exchange resins. Lithium. Lithium carbonate. Lithium carbonate-Lithium bromide. Lithium chloride. Methanolic KOH (see DimethylTormamide). N-PhenylmorphoKne. Potassium amide. Potassium r-butoxide. Pyridine. Quinoline. Rhodium-Alumina. Silver oxide. Sodium acetate-Acetonitrile (see Tetrachlorocyclopentadienone, preparation). Sodium amide. Sodium 2-butylcyclohexoxide. Sodium ethoxide (see l-Ethoxybutene-l-yne-3, preparation). Sodium hydride. Sodium iodide in 1,2-dimethoxyethane (see Tetrachlorocyclopentadienone, alternative preparation) Tetraethylammonium chloride. Tri-n-butylamine. Triethylamine. Tri-methyiamine (see Boron trichloride). Trimethyl phosphite. 

Bases Alumina, see p-Toluenesulfonylhydrazine. Dehydroabietylamine. 1,5-Diazabicyclo [4.3.0]nonene-5. 1,4-Diazabicyclo[2.2.2]octane. l,S-Diazabicyclot5.4.0]undecene-5. 2,6-Di-/-butylpyridine. N,N,-Diethylglycine ethyl ester, see /-Amyl chloroformate. 2,6-Dimethyl-piperidine. Ethanolamine. Lithium diisopropylamide, see Diphenylsulfonium isopropylide. Lithium nitride. Magnesium methoxide. N-Methylmorpholine. Piperidine. Potassium amide. Potassium hydroxide. Potassium triethylmethoxide. Pyridine. Pyrrolidine. Sodium methoxide. Sodium 2-methyl-2-butoxide. Sodium thiophenoxide. Thallous ethoxide. Triethyla-mine. Triphenylphosphine, see l-Methyl-2-pyrrolidone. 

A nionic telomerizations of conjugated diolefins with hydrocarbon acids - are known but suffer from very low catalytic efficiencies. Morton et al. (I) and, later, Pappas et al. (2) used unchelated organosodium compounds to telomerize conjugated diolefins with weak hydrocarbon acids but obtained very low catalyst efficiencies (about 5 grams/gram catalyst). More recently, the anionic telomerization of butadiene and toluene by sodium on oxide supports (3) and sodium in tetrahydrofuran (4) was studied .also, a potassium amide/lithiated alumina catalyst was used to telomerize butadiene (5). 

It has been also demonstrated recently that the H-D exchange reaction between methane and deuterated potassium amide supported on alumina (KND2/AI2O3) proceeds at room temperature [10c], The proposed mechanism is shown schematically in Figure III.4. 

Handa. II Baba. T Ono. Y ll-D exchange between methane and deuteriated potassium-amide supported on alumina. Journal of the Chemical Society Faraday Transactions, 1998 94. 451 -454. 

KNH2/AI2O3 is prepared as follows Alumina and a small amount of Fe203 are heated in the reactor under vacuum at 773 K for 3 h. A piece of potassium metal is then put into the reactor under nitrogen. After evacuation, ammonia is liquefied into the reactor to dissolve the metal. The blue color due to solvated electrons disappears in about 10 min, indicating the formation of potassium amide. After 1 h, the reactor is warmed to room temperature for removing the most of the ammonia and then heated under vacuum at a higher temperature for 1 h. 

Chlorophenyl)propanenitrile (5.0 g, 30 mmol) is dissolved in liquid ammonia (0.60 L) containing potassium amide (0.12 mol). After 5 min of vigorous stirring, sodium nitrate (11 g, 0.13 mol) is added to the red-brown solution. The ammonia is evaporated through a paraffin oil bubbler and the residue absorbed on alumina (25 mL). The dry powder is poured on top of a column filled with basic alumina (0.20 L) and a 1 1 mixture of toluene and hexanes. Upon elution with these solvents and their subsequent evaporation a colorless oil is eluted bp 78-79 °C/2 mmHg 2.40 g (62%). ... 

Ester eliminations are normally one of two types, base catalyzed or pyrolytic. The usual choice for base catalyzed j5-elimination is a sulfonate ester, generally the tosylate or mesylate. The traditional conditions for elimination are treatment with refluxing collidine or other pyridine base, and rearrangement may occur. Alternative conditions include treatment with variously prepared aluminas, amide-metal halide-carbonate combinations, and recently, the use of DMSO either alone or in the presence of potassium -butoxide. 

The mother liquors and the two washes containing methanol are collected and combined. A one normal solution of potassium hydroxide in methanol is added in approximately equal volume to the combined washes and mother liquors. The solution is then filtered and the filter washed with a few ml of methanol. The filtrates are allowed to stand at room temperature for two to three hours to reequilibrate the iso-lysergic acid amides from the mother liquors. About 500 ml of water is then added and the mixture extracted with 2.5 liters of methylene chloride in divided portions in a separatory funnel. The combined extracts are shaken with 25 grams of anhydrous magnesium sulfate and filtered. The filtrate is taken to dryness on the rotary vacuum evaporator, care taken not to heat above 55° C. The material is purified in the same manner as that from the original reaction mixture using approximately one fourth the quantities of solvents and alumina as for the original. 

The preparation of oxazolines from p-hydroxy amides and SOCI2 via the corresponding p-chloro amides under basic conditions is well known and has been discussed earlier. Potassium fluoride on alumina has been reported as a mild alternative to the aqueous or alcoholic bases that are commonly used. The reaction is typically carried out in acetonitrile or tetramethylene sulfone and moderate to good yields of oxazolines and oxazines can be obtained as shown in Scheme 8.29. 

Hydrolysis with powdered potassium hydroxide or potassium fluoride on alumina in r-butyl alcohol converts nitriles to amides without further hydrolysis to carboxlic acids. Under similar conditions, addition of alkyl halides gives iV-alkylcarboxyamides. Less drastic acidic or basic hydrolysis conditions involve disproportionation of alkaline hydrogen peroxide with concomitant hydration of the nitrile (equation 21). 

Pictet-Spengler cyclization, 161 Pinacol rearrangements, 51 B-(3>a-Pinanyl-9-borabicyclo[3.3.1 ]-nonane, 320-321 Piperidine, 183 Piperidine enamines, 16 Piperidines, 18 Piperonal, 232 Piperylene, 372 N-Pivaloylaniline, 69 Platinum catalysts, 321 Podophyllotoxin, 165 Polygodial, 167 Polymethoxyarenes, 368 Polymethylpyrimidines, 345 Polynucleotides, 88 Polyphosphate ester, 437 Polyphosphoric acid, 321-322 Potassioacetone, 73 Potassium-Alumina, 322 Potassium bis(trimcthylsilyl)amide, 38 Potassium f-butoxide, 323 Potassium carbonate, 323 Potassium-18-Crown-6, 322 Potassium cyanide, 324 Potassium cyclopentadienide, 111 Potassium 2,6-di-f-butyl-4-methylphen-oxide, 48... 

Dehydration Alumina (see also Dihydropyrane, preparation). Boric acid. Boron triSuoride. N-Bromoacetamide-Pyridine-SOj. Dicyclohexylcarbodiimide. Diketene. Dimethylform-amide-Thionyl chloride. Dimethyl sulfoxide. Ethylene chlorophosphite. Florisil. Girard s reagent. Hydrobromic acid. Iodine. Mesyl chloride-Sulfur dioxide. Methyl chlorosulfite. Methylketene diethylacetal. Naphthalene-d-sulfonic acid. Oxalic acid. Phenyl isocyanate. Phosgene. Phosphorus pentoxide. Phosphoryl chloride. Phthalic anhydride. Potassium bisulfate. Pyridine. Thionyi chloride. Thoria. p-Toluenesulfonic acid. p-Toluenesulfonyl chloride. Triphenylphosphine dibromide. 

Dehydrohalogenation Alumina, see Sulfur tetrafluoride. Alumina-Potassium hydroxide. Cesium fluoride. l,5-Diazabicyclo[4.3.0]nonene-5. l,4-Diazabicyclo[2.2.2]octane. 1,5-Diazabicyclo[5.4.0]undecene-5. Dimethylaminotrimethylstannane. Dimethyl sulfoxide. Hexamethylphosphoric triamide. Lithium chloride. Lithium dicyclohexylamide. Magnesium oxide. Potassium r-butoxide. Potassium fluoride. Potassium triethylmethoxide. Pyridine, see Nitrosyl chloride. Silver fluoride. Silver nitrate. Sodium amide. Sodium bicarbonate, see Nitryl iodide. Sodium isopropoxide. Triethylamine, see Sulfur dioxide. 

In practice, there have been many other modifications of the RBR conditions, mostly differing in the choice of base used. The most popular base for the RBR is potassium tert-butoxide, either added directly or generated in situ from tert-BuOH and KOH (powdered or supported on alumina). Nonetheless, numerous other bases have been employed for the RBR, including lithium tert-butoxide, l,8-diazabicyclo[5.4.0]undec-7-ene (DBU), lithium bis(trimethylsilyl)amide (LiHMDS), and butyllithium(n-BuLi). ° The stronger bases tend to favor formation of (E)-alkenes (see Section 8.4). 

Potassium fluoride in combination with alumina has been shown to be a good catalyst for the iV-alkylation of carboxamides, lactams and other N-heterocycles using alkyl halides or dialkyl sulfates under mild conditions [47]. The system was also used to AT-alkylate secondary amides and N,N-dialkylate primary amides. Potassium hydroxide and alumina make a useful combination for the catalysis of the selective mono-AT-alkylation of primary amines (e.g. equation 4.6) [48]. 

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