Condensation, phenylurea

Condensation, isatin, 5, 71 Condensation, phenylurea, 3, 93 Condensation, xanthone, 7, 84... 

In a 500-cc. round-bottom flask fitted with a reflux condenser are placed 68 g. of phenylurea (0.5 mole) (Note i) and 120 cc. (i mole) of 42 per cent hydrazine hydrate solution (Note 2). The flask is heated on a steam bath for about twelve hours. The hot mixture is treated with a small amount of decolorizing charcoal (Norite) and filtered. The charcoal is washed with two 15-CC. portions of warm water and the filtrate and washings are then concentrated on a steam bath to about 100 cc. On coolipg in an ice bath a crop of crystals separates and is collected on a filter and washed with two 15-cc. portions of cold water. The filtrate and washings are concentrated to about 25 cc. and another crop of crystals is obtained as before. The total yield of crude compound is 47-52 g. It is white at first but sometimes turns brown on drying. It usually melts below 115° because of some unchanged phenylurea. 

I-Cyano-3-phenylurea, first obtained by the alkaline hydrolysis of 5-anilino-3- -toluyl-l,2,4-oxadiazole, has been prepared by tlic condensation of phenyl isocyanate and the sodium salt of cyanamide. However, in these publications an incorrect structural assignment for the product was made. 1-Cyano-3-phenyl-urea is obtained also, together with other products, by warming gently l-cyano-3-phenylthiourea with caustic soda in the presence of ethylene chlorohydrin, or by gradually adding caustic )otash to a boiling solution of 1-phenyldithiobiuret and ethylene clilorohydrin in ethanol. ... 

In addition, symmetrical diphenylurea may be metalated to give the dianion which then may be condensed with active halogen compounds as shown in Eq. (48). This metallation does not work when applied to urea, phenylurea,... 

To a flask equipped with a reflux condenser are added 68 gm (0.5 mole) of phenylurea and 120 ml (1.0 mole) of 42 % hydrazine hydrate solution. The mixture is refluxed for 12 hr, filtered hot using decolorizing charcoal, and then concentrated to 100 ml. On cooling, the crystalline product separates and it is washed with the minimum amount of water. The filtrate is concentrated to 25 ml and another crop of crystals is collected. The total yield of the crude... 

Condensation of phenyl isocyanate with an aqueous solution of the sodium salt of cyanamide and acidification affords l-cyano-3-phenylurea (4). ... 

The condensation of benzil and phenylurea 15 followed by benzilic acid rearrangement and decarboxylation afforded l-benzhydryl-3-phenylurea derivatives 16. ... 

Attempted chlorosulfonation of 3- and 4-chlorophenylureas failed, presumably as a result of a combination of unfavourable stereoelectronic factors. Sulfonylureas are an important group of highly potent herbicides which may be used for selective weed control in cereals at very low dose rates. Herbicidal (p-sulfamoyl)phenylureas were synthesized from the appropriate phenylureas by mixing them with chlorosulfonic acid at 12-15 C, followed by heating at 60 C and the resultant p-(chlorosulfonylphenyl)ureas were condensed with the amine. °... 

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