Dimethylethanolamine catalyst

Bis-hexamethylenetriamine t-Butyl toluenediamine Dibutyltin bisisooctyl thioqlycolate JM,N-Diethylcyclohexylamine N,N-Dimethylethylamine Imidazole Lead 2-ethylhexoate N-Methyldicyclohexylamine PEG-2 C13-15 alkyl amine N,N, N",N"-Pentamethyldiethylenetriamine 1,3-Pentanediamine Phenylmercuric propionate Potassium 2-ethylhexanoate N,N,N, N -Tetramethyl-1,3-propanediamine catalyst, PU coatings Dibutyltin diacetate Triethylene diamine catalyst, PU elastomers Diazabicycloundecene catalyst, PU flexible foams Dicoco methylamine catalyst, PU foam slabstock Dimethylethanolamine catalyst, PU foams... 

Typical procedure. l-Methyl-d-cyanobutyl N-[l-(l-naphthyl)ethyl]carbamates 614 (R = Me, n = 4) [439]. Procedure A A stirred solution of 5-cyanopentan-2-ol (8.0 g, 70.8 mmol), (R)-( —)-l-(l-naphthyl)ethyl isocyanate (13.9 g, 70.8 mmol), dry benzene (150 mL), and two drops of dimethylethanolamine catalyst was heated at reflux under N2 for 24 h. The solvent was then removed in vacuo, and the crude diastereomeric carbamates were completely separated by chromatography (on acidic alumina, eluting with CHCla/hexane, 2 1) using an automated preparative LC system. A total of 8.9 g (81%) of the high R( (R,R) diastereomer was collected as a yellow viscous oil. 

Epoxy-dlol Adduct. The epoxy-diol adducts were prepared using standard techniques ( 1 ) by heating a mixture of two moles of diol with one mole of epoxy resin at 130-140°C for 8 hours using 1% N,N-dimethylethanolamine as catalyst. Epoxy-diol adducts prepared in this manner showed the absence of epoxy absorption in the infrared spectrum. 

Thus, by the propoxylation of DETA with around 8-10 mols of PO/mol of DETA, by using dimethylethanolamine as catalyst, aminic polyols of low hydroxyl number (390-420 mg KOH/g) are obtained, with low viscosity of around 6,000-9,000 mPa-s, at 25 °C [1,10,11] ... 

This type of finish is an extension of the one-pack moisture-curing type. It is virtually the same finish, to which a small quantity of catalyst is added just before use. Tertiary amines, such as N,N-dimethylethanolamine [HO CH2 CH2 N(CH3)2], are most frequently used as catalysts. Even if the moisture content of the air is low, the finish will harden rapidly, but the more reliable drying performance is obtained at the expense of a limited pot-life. Unfortunately, the activator is non-polymeric and so cannot be used for pigment dispersion. Pigments are dispersed in pre-polymer and must be free from moisture, as in the one-pack composition. The uncatalysed finish is water-sensitive, presenting a shelf-life storage problem as before. 

Various catalysts are used to prepare polyurethane at a relatively low temperature and with a much faster rate of polymerisation than would be the case with an uncatalysed reaction. Catalysts may be classified into two broad categories namely, amine (basic) compounds and organometalhc complex compounds. Tertiary amine is stiU one of the most frequently used urethane catalysts. Commonly used amine catalysts are triethylenedi-amine (TEDA), l,4-diazabicyclo[2.2.2]octane (DABCO), triethylamine (TEA), dimethylethanolamine (DMEA) and dimethylcyclohexylamine (DMCHA). The catalysis mechanism of tertiary amine catalysed urethane reaction involves complexation of the amine with isocyanate groups, followed by reaction of the complex with alcohol to produce polyurethane. A list of catalysts used in polyurethane preparation is given in Table 6.4. 

A,A-dimethylethanolamine is one of the preferred amines, because its combination of good catalytic activity, adequate volatility and relatively low toxicity is an effective compromise. Amines are not equally effective catalysts for all types of isocyanate and care must be taken about selecting aliphatic isocyanates in particular (p. 233) to achieve best cure rates. 

Catalyzed Moisture Cures - This two component system is the same as the one package moisture cme system except a tertiary amine catalyst such as N,N-dimethylethanolamine is added just before application. This shortens cure time and increases the crosslink density of the film for better chemical resistance. As soon as the catalyst is added there is limited pot-life before gelation occms. 

Both primary and secondary amines are to be avoided since they will react with the isocyanates. Triethylene diamine and dimethylethanolamine are commonly used tertiary amine catalysts. 

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