Solutions, formaldehyde Fractional condensation

In the early oxidation nitration preparation of DNPOH, the yield is relatively low (59-63 %), the product needs further purification, there is formaldehyde condensation reaction and other serious problems. Jeong et al. [63] modified the oxidation nitration process to optimize the oxidation nitration conditions of silver nitrate, in which aqueous formaldehyde solution (mass fraction of 35 %) was used for hy-droxymethylation and its reaction conditions were optimized, and a yellow solid DNPOH was obtained after extraction with methylene chloride and distillation. The average yield of DNPOH was more than 90 % and the mass fraction was more than 97 %. Based on these results, Grakauskas et al. [40-42, 65] used potassium ferri-cyanide as catalyst and potassium persulfate as oxidant to synthesize DNPOH. In this method, with potassium(sodium) ferricyanide and over potassium(sodium) persulfate, nitrite substitution reaction of nitroethane with sodium nitrite occurred, and then further reacted with formaldehyde under basic conditions, and finally DNPOH was extracted out with ethyl acetate under acidic conditions. Product was obtained through potassium distillation. The reaction mechanism is ... 

If the small proportion of acetone present in synthetic methanol is objectionable it may be removed when present in quantities up to 1 per cent by the following procedure (Morton and Mark, 1934). A mixture of 500 ml of methanol, 25 ml of furfural and 60 ml of 10 per cent sodium hydroxide solution is refluxed in a 2-litre round-bottomed flask, fitted with a double surface condenser, for 6-12 hours. A resin is formed which carries down all the acetone present. The alcohol is then fractionated through an efficient column, the first 5 ml which may contain a trace of formaldehyde being rejected. The recovery of methanol is about 95 per cent. 

Dihydro-l//-2-benzotelliirin (Kongalite Method)2 34 g (0.17 mol) of sodium formaldehyde sulfoxylate, 26 g (0.65 mol) of sodium hydroxide, and 100 ml of water are placed in a flask fitted with a stirrer, a reflux condenser, and a nitrogen inlet tube. The flask is flushed with nitrogen, 15 g (0.12 mol) of fine tellurium powder is added, and the mixture is stirred and heated on a water bath for 30 min. 100 ml of ethanol and a solution of 25 g (0.09 mol) of 2-(2 -bromoethyl)benzyl bromide dissolved in 150 mi of hot ethanol are added. The mixture is stirred and heated under reflux for 2 h, the ethanol is distilled off, and the residue is ground, then extracted with a mixture of 300 ml of water and 300 ml of diethyl ether. The diethyl ether layer is separated, washed with water, dried with anhydrous sodium sulfate, filtered, and fractionally distilled yield 8.5 g b.p. 116-12670.3 torr. The residue from the extraction is boiled with 50 m/of ethanol, the mixture is filtered hot, and the filtrate allowed to cool. The crystals are collected (3.8 g) and the combined product fractions are recrystallized from methanol whereby the methanol solution is cooled in dry ice yield 12.3 g (54%) m.p. 64°. 

Nitrilotris(methylenephosphonic acid) (11 n = 3) 322 Ammonium chloride (17.8 g, 0.33 mole), crystalline phosphorous acid (82 g, 1 mole), water (100 ml), and concentrated hydrochloric acid (100 ml) are heated together to the boiling point in a flask fitted with a thermometer, stirrer, reflux condenser, and dropping funnel. 37% aqueous formaldehyde (160 ml, 2 moles, 100% excess) is added dropwise during 1 h and the whole is heated under reflux for a further hour. When the solution is then kept overnight most of the product crystallizes. Collection, washing with aqueous acetone, and drying at 120° affords it (74.9 g, 75%) with m.p. 210-215°. Concentration of the mother-liquor provides a second fraction. 

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