Hexamethylene reaction rates

Investigation of template poly condensation kinetics has only been studied within a very narrow scope. Polymerization of dimethyl tartrate with hexamethylene diamine was found to be enhanced by using as a template poly(vinyl pyrrolidone), poly(2-vinyl pyridine), or polysaccharides and poly(vinyl alcohol), poly(4-vinyl pyridine). In this case, the template can be treated as a catalyst. No information exists on the influence of the template on the order of reaction. The increase in molecular weight of the polymerization product by the template can be induced by a shift of equilibrium or by an increase in the reaction rate. A similar increase in the reaction rate was observed when poly(4-vi-nyl pyridine) was used in the synthesis of poly(terephtalamides) activated by triphenyl phosphite.The authors suggested that a high molecular weight template was involved in the increase of the local concentration of the substrate (terephthalic acid) by adsorption and activation via N-phosphonium salt of poly(4- vinyl pyridine). 

Addition copolymers containing IBM retain much of this reactivity with primary alcohols. As seen in Table 3, the reaction rate constant of 1-butanol with polymerized IBM is about half that of monomeric IBM under the same conditions (3). Thus the reactivity of IBM-containing polymers is similar to that of other primary aliphatic isocyanates such as hexamethylene diisocyanate. This very good retention of NCO reactivity allows the use of IBM to incorporate NCO functionality into a variety of vinyl copolymers. In general, IBM-containing copolymers retain >90% of the theoretical isocyanate functionality. 

This finds some support in a comparison of solution viscosities with polymerization time of a few isolated cases of Diels-Alder polymerization reactions. In the polymerization of 2,5-dimethylene-3,4-diphenylcyclo-pentadieneone with N.N -hexamethylene-fo s-maleimide, the reduced viscosity of the polymer increases from 0.97 after 1 hr to 1.20 after six hours (7). It is necessary to assume that the rate controlling step in this reaction is neither the formation of the initial adduct nor the loss of carbon monoxide. The inherent viscosity of the l,6-6is-(cyclopenta-dienyl)hexane-quinone copolymer increases from 0.10 after sixteen hours to 0.12 after twenty four hours reaction time in refluxing benzene (14). 

Figure 6. Rate of change of specific viscosity as a function of polymer concentration for the reaction between hexamethylene diisocyanate and a -dihydroxy polystyrene in toluene at 80°C. [NCO]0 [OH]0 = 1...

One other application of modified wood solutions is the formation of filaments or fibers [20]. After making a phenol solution of acetylated wood, hexamethylene tetramine was added and the mixture was heated at 120°C to promote the addition-condensation reaction for a resinified solution with high spinnability. From this solution, filaments were spun and hardened in an oven at a certain heating rate. The maximum temperature for hardening was 250°C, and continuous filaments could easily be obtained by this method. 

The rate coefficients for the reactions of hexamethylene diisocyanate at least with hydroxyl appear large in relation to those for the aromatic isocyanate. Others have found the aliphatic isocyanates consistently less reactive than unhindered aromatic isocyanates. The wide variation in the reported rates of the other reactions, not always consistent with structure of the reactants, and variations in activation energies in any given series are unexpected. Several of these data are not in eement with what... 

Effect of Hydrolyzable Chlorine on Activity of Tin Catalysts. The effect of small amounts of hydrolyzable chlorine on the catalytic activity of DBTDL was studied on the model aliphatic system—isocy-anatoethyl methacrylate and n-butanol. The presence of the hydrolyzable chlorine in isocyanate usually decreases the reactivity of isocyanates in the urethane reaction. The results of measurements of the chlorine effect on the change of the rate constant is summarized in Figure 8. It was determined that the very small amounts of the hydrolyzable chlorine, especially in the form of carbamoyl chloride, increased at the beginning the rate constant for the urethane reaction catalyzed by DBTDL and after achieving the maximum at 500 ppm of chlorine the reactivity decreased. This effect was not observed when benzoyl chloride was used in place of carbamoyl chloride. It was assumed that the activation effect of the chlorine was due to the interaction of the carbamoyl chloride with the DBTDL catalyst. In order to understand this effect, the interaction of DBTDL with carbamoyl chloride of hexamethylene diisocyanate (with and without the presence of n-butanol) was studied using the IR technique. Results are summarized in Figure 9. 

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