Dimethylformamide reactions

Dimethylformamide, reaction with dimethyl sulfate, 47, 52 reaction with phosphorus oxychloride and cyclohexanone, 16,18 Dimethylformamide-dimethyl sulfate complex, preparation of, 47,... 

In an attempt to prepare 2j3-azidocholestan-3-one (76) from the 2ct-bromo derivative (77), Edwards and Purushothaman observed an interesting shortcoming in this general procedure. Although 2-chlorocyclohexanone gave a high yield of the 2-azidoketone when treated with sodium azide in dimethylformamide, reaction of lithium azide and the bromo compound (77) in the same solvent produced... 

Ketones may be prepared by the reaction of the lithio intermediate with a nitrile (Reaction 11) (6). Nitriles possessing no alpha hydrogens work best in this reaction. Formyl derivatives of aromatics may be synthesized by treating the lithiated species with dimethylformamide (Reaction 12) (19). Carboxylic acids are readily available by carbonation of such lithio intermediates (14,16). Treatment of these lithio intermediates with aryl or alkyl isocyanates yields amides (Reaction 13) (10). 

The use of dimethylformamide (b.p. 153°) as a solvent and diluent often increases the yield materially. The vigour of the exothermic reaction which occurs with a relatively reactive aryl hahde is moderated and, furthermore, the dimethylformamide is easily removed from the reaction product since it is water soluble. Aryl hahdes which are inert under the usual Ullmann conditions do not react in the presence of dimethylformamide. 

The experimental conditions for conducting the above reaction in the presence of dimethylformamide as a solvent are as follows. In a 250 ml. three-necked flask, equipped with a reflux condenser and a tantalum wire Hershberg-type stirrer, place 20 g. of o-chloronitrobenzene and 100 ml. of diinethylform-amide (dried over anhydrous calcium sulphate). Heat the solution to reflux and add 20 g. of activated copper bronze in one portion. Heat under reflux for 4 hours, add another 20 g. portion of copper powder, and continue refluxing for a second 4-hour period. Allow to cool, pour the reaction mixture into 2 litres of water, and filter with suction. Extract the solids with three 200 ml. portions of boiling ethanol alternatively, use 300 ml. of ethanol in a Soxhlet apparatus. Isolate the 2 2- dinitrodiphenyl from the alcoholic extracts as described above the 3ueld of product, m.p. 124-125°, is 11 - 5 g. 

The idea is to have everything in place before the oxygen is applied. So, lOOg of safrole is in the addition funnel and stirring around in the reaction flask are 10.6g of PdCU, 60g CuCI and 500mL of aqueous dimethylformamide (made by mixing 62.5mL dH20 and 437,5mL DMF). Dimethylformamide (DMF) is not the same as the watched chemical known as N-methylformamide. 

Amino-5-nitrothiazole, on treatment with arenesulfonyl halides and dimethylformamide at 140 C, gives (5-nitro-2-thiazolyl)amidme (274) (Scheme 168) (507, 508). The condensation products of the reaction of 2-aminothiazole derivatives with various aldehydes are grouped in Tables... 

If anhydrous dimethylformamide is used as solvent, the reaction is complete within 30 min at room temperature, and the products are generally obtained in high yield. 

Trifluoromethanesulfonic acid is miscible in all proportions with water and is soluble in many polar organic solvents such as dimethylformamide, dimethyl sulfoxide, and acetonitrile. In addition, it is soluble in alcohols, ketones, ethers, and esters, but these generally are not suitably inert solvents. The acid reacts with ethyl ether to give a colorless, Hquid oxonium complex, which on further heating gives the ethyl ester and ethylene. Reaction with ethanol gives the ester, but in addition dehydration and ether formation occurs. 

Extraction of hemiceUulose is a complex process that alters or degrades hemiceUulose in some manner (11,138). Alkaline reagents that break hydrogen bonds are the most effective solvents but they de-estetify and initiate -elimination reactions. Polar solvents such as DMSO and dimethylformamide are more specific and are used to extract partiaUy acetylated polymers from milled wood or holoceUulose (11,139). Solvent mixtures of increasing solvent power are employed in a sequential manner (138) and advantage is taken of the different behavior of various alkaUes and alkaline complexes under different experimental conditions of extraction, concentration, and temperature (4,140). Some sequences for these elaborate extraction schemes have been summarized (138,139) and an experimenter should optimize them for the material involved and the desired end product (102). 

Furalazine, Acetylfuratrizine, Panfuran-S. Heating nitrovin in butanol or dimethylformamide at 100—130°C affords furalazine, 6-[2-(5-nitro-2-furanyl)ethenyl]-l,2,4-triazine-3-amine (34). An improved synthesis originates with 5-nitro-2-furancarboxaldehyde and acetone, proceeds through 4-(5-nitro-2-furanyl)-3-buten-2-one followed by a selenium dioxide oxidation to the pymvaldehyde hydrate, and subsequent reaction with aininoguariidine (35). Furalazine, acetylfuratrizine (36), and the A[-A/-bis(hydroxymethyl) derivative, Panfuran-S, formed from the parent compound and formaldehyde (37), are systemic antibacterial agents. 

Catalysts. Silver and silver compounds are widely used in research and industry as catalysts for oxidation, reduction, and polymerization reactions. Silver nitrate has been reported as a catalyst for the preparation of propylene oxide (qv) from propylene (qv) (58), and silver acetate has been reported as being a suitable catalyst for the production of ethylene oxide (qv) from ethylene (qv) (59). The solubiUty of silver perchlorate in organic solvents makes it a possible catalyst for polymerization reactions, such as the production of butyl acrylate polymers in dimethylformamide (60) or the polymerization of methacrylamide (61). Similarly, the solubiUty of silver tetrafiuoroborate in organic solvents has enhanced its use in the synthesis of 3-pyrrolines by the cyclization of aHenic amines (62). 

Hydrolysis of TEOS in various solvents is such that for a particular system increases directiy with the concentration of H" or H O" in acidic media and with the concentration of OH in basic media. The dominant factor in controlling the hydrolysis rate is pH (21). However, the nature of the acid plays an important role, so that a small addition of HCl induces a 1500-fold increase in whereas acetic acid has Httie effect. Hydrolysis is also temperature-dependent. The reaction rate increases 10-fold when the temperature is varied from 20 to 45°C. Nmr experiments show that varies in different solvents as foUows acetonitrile > methanol > dimethylformamide > dioxane > formamide, where the k in acetonitrile is about 20 times larger than the k in formamide. The nature of the alkoxy groups on the siHcon atom also influences the rate constant. The longer and the bulkier the alkoxide group, the lower the (3). 

The most suitable oxidizing agent is potassium ferricyanide, but ferric chloride, hydrogen peroxide ia the presence of ferrous salts, ammonium persulfate, lead dioxide, lead tetraacetate or chromate, or silver and cupric salts may be useful. Water mixed, eg, with methanol, dimethylformamide, or glycol ethers, is employed as reaction medium. 

Dimethylformamide. The industrial solvent dimethylformarnide [68-12-2] is manufactured by the reaction between carbon monoxide and dimethylamine [124-40-3],... 

The reaction product of 4,4 -bismaleimidodiphenylmethane and 4,4 -diaminophenylmethane, known as Kerimide 601 [9063-71-2] is prepolymerized to such an extent that the resulting prepolymer is soluble in aprotic solvents such as /V-methy1pyrro1idinone [872-50-4] dimethylformamide [68-12-2] and the like, and therefore can be processed via solution techniques to prepreg. Kerim ide 601 is mainly used in glass fabric laminates for electrical appHcations and became the industry standard for polyimide-based printed circuit boards (32). 

In a 200-ml, three-necked flask equipped with a mechanical stirrer, a thermometer, and a gas-inlet tube are placed 41.2 g. (0.2 mole) of 2,6-di- er/-butylphenol (Note 1) in 75 ml. of dimethylformamide (Note 2) and 2.5 g. (0.0075 mole) of salcomine (Note 3). With stirring, oxygen is introduced at such a rate that the temperature does not exceed 50°. This is continued for 4 hours. At the end of the reaction the temperature drops to about 25°. The reaction mixture is then poured onto 500 g. of crushed ice and 15 ml. of 4N hydrochloric acid. A yellow-brown precipitate is formed. The solid material is collected by suction filtration and washed on the filter three times with 50-ml. portions of IN hydrochloric... 

Reaction of these polyols with an excess of isocyanate yields isocyanate terminated materials which are then chain extended by an amine such as hydrazine (NH2NH2) or ethylenediamine. The fibre is usually spun from solution in dimethylformamide. 

In a 3-1. three-necked round-bottomed flask, fitted with a sealed stirrer, a dropping funnel, and a reflux condenser, is placed 80 g. (1.1 moles) of dimethylformamide (Note 1). The flask is immersed in an ice bath, and the internal temperature is maintained at 10-20°, while 169 g. (1.1 moles) of phosphorus oxychloride is added through the dropping funnel over a period of 15 minutes. An exothermic reaction occurs with the formation of the phosphorus oxychloride-dimethylformamide complex. The ice bath is removed, and the mixture is stirred for 15 minutes (Note 2). 

Spray solution Ilb Dissolve 1 g 7V-(l-naphthyl)ethylenediamine dihydrochloride in 50 ml dimethylformamide and 50 ml hydrochloric acid (< Hci = 4 mol/1) with warming. If the cooled solution is not clear it should be filtered. A pale violet coloration does not interfere with the reaction [4]. 

NaBH4 is soluble in water, alcohols, pyridine, dioxane, dimethoxyethane, diglyme and triglyme. All these solvents, as well as aqueous tetrahydrofuran and aqueous dimethylformamide, have been used for reductions. The reductions go very slowly in di- and triglyme so these solvents are not suitable for preparative work. In some reductions in dry pyridine and dry dimethyl sulfoxide, reaction only takes place on aqueous work-up. This... 

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