Ureas condensation

The reaction conditions can be varied so that only one of those monomers is formed. 1-Hydroxy-methylurea and l,3-bis(hydroxymethyl)urea condense in the presence of an acid catalyst to produce urea formaldehyde resins. A wide variety of resins can be obtained by careful selection of the pH, reaction temperature, reactant ratio, amino monomer, and degree of polymerization. If the reaction is carried far enough, an infusible polymer network is produced. 

With the present state of knowledge it appears that in the first part of the second-stage methylol ureas condense with each other by reaction of an CH20H group of one molecule with an NH2 group of another (Figure 24.2). 

Toxicological investigations of tetrakishydroxymethylphosphonium salts [(HOCH2)4P+ X X = Cl, THPC X = (S04)0,5, THPS] and their derivatives, used for the flame-retardant treatment of cotton, have been carried out (cf. Table 9). It was concluded that the salts and their urea condensation products are harmful to animals on oral or dermal application. Moreover, at sublethal doses, the salts gave no evidence of carcinogenesis in rodents when applied by the dermal or gavage routes. The polymers produced from them did not exhibit any adverse reactions194. 

Another category of durable hand builders are formaldehyde-containing thermosetting polymers. These products are usually supplied as dispersions or aqueous solutions of precondensates of urea or melamine with formaldehyde, for example di-methylol urea or di- to hexa-methylol melamine and their methyl ethers. The thermosetting polymers are comparatively inexpensive and provide fabrics with stiffness and resilience. However, they have a tendency to reduce abrasion resistance, yellow after exposure to heat, and release formaldehyde. Melamine-based hand builders are more highly crosslinked than urea-based products and are accordingly more durable. Butylated urea condensates are especially useful for rayon fabrics (see also Chapter 5 Easy-care and durable press finishes of cellulosics). 

It has been documented that the Biginelli reaction involves an aldehyde-urea condensation to form A/ -acyliminium ion as the key intermediate, followed by the addition of a 7r-nucleophile to the electron-deficient A/ -acyliminium ion and finally a ring closure, as illustrated below. 

Formaldehyde/urea condensate Formaldehyde/urea copolymer Form-aldehyde/urea polymer Formaldehyde/urea precondensate Formaldehyde/urea epolymer Formaldehyde/urea resin. See Urea-formaldehyde resin... 

Synonyms Eormaldehyde copolymer with urea Eormaldehyde/urea condensate Eormaldehyde/urea copolymer Eormaldehyde/urea polymer Eormaldehyde/urea precondensate Eormaldehyde/urea prepolymer Eormaldehyde/urea resin Formalin/urea copolymer Methylolurea resin Paraformaldehyde/urea polymer Paraformaldehyde/urea resin Polynoxylin Polyoxymethylene urea (INCI) UF Ure ormaldehyde adduct Urea/formaldehyde condensate Urea/formaldehyde copolymer Urea/formaldehyde oligomer Urea/formaldehyde polymer Urea/ formaldehyde precondensate Urea/formaldehyde prepolymer Urea, polymer with formaldehyde Classification Amino resin thermosetting resin Definition Thermosetting resin formed from condensation reaction of formaldehyde with urea formu/a (CH,N20 CH2O),... 

Phosphonium, tetrakis (hydroxymethyl)-, sulfate (2 1) (salt), polymer with urea. See Tetrakishydroxymethyl phosphonium sulfate-urea condensate... 

Proaid LCF. See Methyl hydroxystearate Probake . See Calcium propionate Proban CC.. See Tetrakishydroxymethyl phosphonium chloride-urea condensate Probenz -P, Probenz PG. See Potassium benzoate... 

Retarder TSA. See Salicylic acid Retardoi AC. See Tetrakishydroxymethyl phosphonium chloride-urea condensate Retardoi C. See Tetrakis (hydroxymethyl) phosphonium chloride Retardoi S. See Tetrakis (hydroxymethyl) phosphonium sulfate Reten 157. See Acrylamides copolymer Reten 210. See Polyquaternium-5 Reten 215. See Acrylamides copolymer Reten 220. See Polyquaternium-5 Reten 235. See Acrylamides copolymer Reten 300. See Polyquaternium-14 Reten 420. See Polyacrylamide Reten 421, 423, 425. See Acrylamide/sodium acrylate copolymer... 

Tetrakishydroxymethyl phosphonium chloride polymer with urea. See Tetrakishydroxymethyl phosphonium chloride-urea condensate Tetrakishydroxymethyl phosphonium chloride-urea condensate CAS 27104-30-9... 

Synonyms Phosphonium, tetrakis (hydroxymethyi)-, suifate (2 1) (salt), polymer with urea Tetrakishydroxymethyi phosphonium suifate poiymerwith urea Tetrakis (hydroxymethyi) phosphonium suifate-urea condensation prod. Tetrakis (hydroxymethyi) phosphonium suifate (2 1), urea poiymer Classification Polymer Empirical (C4H12O4P CH4N2O V204S)x... 

Tetrakis (hydroxymethyl) phosphonium sulfate-urea condensation prod. Tetrakis (hydroxymethyl) phosphonium sulfate (2 1), urea polymer. See Tetrakishydroxymethyl phosphonium sulfate-urea condensate 1,3,4,6-Tetrakis hydroxymethyl tetrahydro imidazo (4,5-D) imidazole-2,5-dione. See Tetramethylolacetylene diurea N,N,N, N -Tetrakis (2-hydroxypropyl) ethylenediamine. See Tetrahydroxypropyl ethylenediamine... 

Various attempts have been made to produce slow-acting nitrogen fertilisers. Reasonable results have been obtained with such products as resin- or polymer-coated granules of ammonium nitrate (26% N), sulphur-coated urea prills (36% N) (soil bacteria slowly break down the yellow sulphur in the soil), urea condensates and urea formaldehydes (30 0% N). At present these types of fertiliser are considered too expensive for farm cropping but are used in amenity and production horticulture. 

Like the polyamides, the melamine or urea condensation products can be N-alkylated with formaldehyde and an alcohol such as methanol or butanol. The resulting compositions have good solubility in common solvents and are used in textile treatment and protective coatings. 

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