Catalysts polyamines

Two-component systems consist of (1) polyol or polyamine, and (2) isocyanate. The hardening starts with the mixing of the two components. Due to the low viscosities of the two components, they can be used without addition of solvents. The mass ratio between the two components determines the properties of the bond line. Linear polyols and a lower surplus of isocyanates give flexible bond lines, whereas branched polyols and higher amounts of isocyanates lead to hard and brittle bond lines. The pot life of the two-component systems is determined by the reactivity of the two components, the temperature and the addition of catalysts. The pot life can vary between 0.5 and 24 h. The cure at room temperature is completed within 3 to 20 h. 

The final resin product is obtained by reacting (curing or crosslinking) the above di-epoxide with acid anhydrides or polyamines. The curing agents (sometimes incorrectly called catalysts) react with the three-membered epoxide rings to produce a highly crosslinked polymer. 

When EA adsorption occvured under N2 flow at 583 K on H-EDTA-MOR catalyst without NH3, El, higher polyamines, and PA were formed (Stage A in Figure 5). But, when an excess amount of NH3 (NH3/EA=50) was introduced in... 

Reduction of azides is a classical approach to primary amine synthesis. Treatment of 17 with sodium azide in DMF or in THF/H2O mixtures in the presence of phase transfer catalysts effects a quantitative conversion to the corresponding polymeric azide, 27. Recently the reduction of azides to primary amines via hydrolysis of iminophosphoranes produced by interaction of the azide with triethyl phosphite was reported.30 Application of this technique to the azidomethyl polymer, 27, as shown below, failed to produce a soluble polyamine. 

Polyamides containing a-aminoacid units are readily obtained by reaction of bisazlactones (2-oxazolin-5-ones) with diamines. When polyamines such as diethylenetriamine (DETA) or triethylenetetramine (TETA) are used as the diamine component, the resultant polyamides readily cyclodehydrate above 200°C to produce polymers containing 2-imidazolin-5-one units in the backbone. Polyamides derived from simple diamines (e.g. 1,6-hexanedi amine) cyclodehydrate only in the presence of a suitable catalyst. Carboxylate salts and certain Lewis acids have been found to be efficient catalysts for this transformation. 

The investigation of the chemical modification of dextran to determine the importance of various reaction parameters that may eventually allow the controlled synthesis of dextran-modified materials has began. The initial parameter chosen was reactant molar ratio, since this reaction variable has previously been found to greatly influence other interfacial condensations. Phase transfer catalysts, PTC s, have been successfully employed in the synthesis of various metal-containing polyethers and polyamines (for instance 26). Thus, the effect of various PTC s was also studied as a function of reactant molar ratio. 

Arsenic compounds can be very effective corrosion inhibitors but their toxicity, ineffectiveness in hydrochloric acids above 17% active and in the presence of H S, and their ability to poison refinery catalysts has limited their use (148). Epoxy resins have been coated onto metal surfaces and cured with a polyamine to reduce corrosion (149). 

The last work pertaining to the discovery of new catalysts is perhaps the most novel approach to be reported thus far. In one of the earliest approaches taken toward catalyst development, Menger et al. (61) attempted to find catalysts for phosphate ester hydrolysis. A series of eight functionalized carboxylic acids were attached to polyallylamine in various combinations. Each of these polymers were then treated with one of three metals, Mg2+, Zn2+, or Fe3+. The different members of each library were identified by the relative percentages of each carboxylic acid attached to the polyamine. For example, one polymer possessed 15% Oct, 15% Imi, 15% Phe, and 5% Fe3+. There is no attempt to identify the location of the various carboxylic acids in a given polymer. This approach is novel since each system consists of an ensemble of different ligands with the carboxylic acids positioned in various locations. Each polymer within a given ratio of carboxylic acids consists of a combinatorial library of potential catalysts. 

It is worth mentioning at this point that according to Normant et al. (1975) simple polyamines such as tetramethylethylenediamine (TMEDA) are even more active than [2.2.2]-cryptand in the benzylation of acetates in acetonitrile under liquid-solid conditions. These authors suggested that the activity was due to salt solubilization by cation complexation and not to formation of a quaternary ammonium ion since the latter showed no activity. This statement, however, is not in line with the results of Cote and Bauer (1977), who were unable to detect any interaction between K+ and TMEDA in acetonitrile. Furthermore, Vander Zwan and Hartner (1978) found Aliquat 336 (tricaprylylmethylammonium chloride) to be almost as effective as TMEDA in this reaction (Table 30). It might well be, however, that in amine-catalysed benzylation reactions the quaternary salt formed in situ acts both as a reactant and as a phase-transfer catalyst, since Dou et al. (1977) have shown that the benzyltriethylammonium ion is a powerful benzylation agent. 

Recently another family of dendrimers has become commercially available. These polyamines were developed by Meijer and de Brabander-van den Berg of DSM Research and are based on Vogtle s initial synthesis [7]. In this case the troublesome reduction step was performed using a Raney cobalt hydrogenation catalyst and other process improvements have permitted this synthesis to be continued up to the fifth generation with multikilogram quantities available. 

A) S. Custodero, ItalP 522944 (1955) CA 53, 3698 (1959) [Synthetic resin-base expls are prepd by incorporation of oxidizers into a liquid polymer which is then solidified by addn of a suitable catalyst. Thus, to 20% of a mixt contg 100 parts Araldit D and 9—lOps 951 (an alipahtic polyamine), 80% NaC103 was added with slow stirring to obtain a homogeneous paste. After it was shaped into the desired form by means of a press, it hardened on standing for... 

Although the vast majority of this review has been concerned with homogeneous systems, supported catalyst and single-crystal studies of rhodium are important topics that have also been considered by some researchers. This topic extends and dovetails nicely with the discussion of the interactions of acyclic and cyclic polyamine ligands and Schiff... 

The Maruoka group s further efforts toward simplification of the catalyst have led to the design of new, polyamine-based chiral phase-transfer catalysts of type 15, with expectation of the multiplier effect of chiral auxiliaries, as illustrated in Scheme 5.10 [13]. The chiral efficiency of such polyamine-based chiral phase-transfer catalysts (S)-15 was examined by carrying out an asymmetric alkylation of glycine derivative 2 under phase-transfer conditions. Among various commercially available polyamines, spermidine- and spermine-based polyammonium salts were found to show moderate enantioselectivity. In particular, the introduction of a 3,4,5-trifluor-ophenyl group at the 3,3 -positions of chiral binaphthyl moieties showed excellent asymmetric induction. 

Polycondensation of aromatic primary diamines and aromatic dibromides gave high molecular weight polyamine (Mw > 15 000) irrespective of the m-and p-substituted positions of both monomers (Scheme 12). In this polycondensation, BINAP was effective as a ligand of the Pd(0) catalyst use of P(f-butyl)3, which was effective for the above polymerization using secondary diamines, afforded polymer in a low yield [65,66]. When BINAP was used... 

The Co(m)-complex of cyden, Co(m)Cyc, is one of the most effedive synthetic catalysts discovered so far for the hydrolysis of supercoiled DNAs [59]. The hydrolytic nature of DNA cleavage by the Co(m) complexes of polyamines including cyden has been well documented [57, 58]. The mechanism illustrated in 25 has been proposed [57] for the catalytic action of the Co(m) complexes. Given the remarkable enhancement of proteolytic activity of Cu(n)Cyc upon attachment to PCD [49], we tested the activity of Co(m)Cyc in phosphodiester hydrolysis to see if it is also enhanced greatly upon attachment to PCD derivatives [61, 62]. 

As an accelerator in conjunction with another catalyst or with a curing agent such as polyamine, polyamide, or anhydride... 

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