Jacek Lubczak

New melamine resins. I. Synthesis of reactive solvents for melamine

Some results are presented on the studies of reactive solvents for melamine obtained from acetone and formaldehyde in the presence of potassium bicarbonate or triethylamine as catalysts. The chemical structure of the solvents, as well as their ability to dissolve melamine, have been determined. The mechanism of melamine dissolution in the reactive solvents has been analyzed by using the 1H-NMR technique.

Polyurethane Foams of Improved Thermal Stability

In reactions of polyetherols prepared from hydroxymethyl derivatives of uric acid and typical oxiranes with isocyanates and water one obtains a new group of polyurethane foams containing purine rings in their structure. These polyurethanes withstand prolonged heating at temperatures as high as 200°C. Preliminary results on the effect of the type of polyetherol and the composition used in preparation of the polyurethane foams on their properties are presented. The results of studies on thermal stability and mechanical properties of the foams before and after thermal treatment are also reported.

Reactions of hydroxymethyl derivatives of uric acid with oxiranes. I. Synthesis of polyetherols with purine rings

Preliminary results on the utilization of uric acid in the synthesis of a new group of polyetherols with purine rings are presented. The polyetherols were prepared in a two-stage process. First, hydroxymethyl derivatives of uric acid were obtained from an uric acid and formaldehyde solution. This intermediate was then reacted with ethylene oxide or propylene oxide without any additional solvent. The structure of the intermediates and polyetherols and some of their physical properties were determined, and the possibilities of application of the polyetherols in manufacturing thermostable polyurethane foams were tested.

Study of reaction between N,N,N′,N′,N′-pentakis (hydroxymethyl) melamine and ethylene or propylene oxide

The effects of the kind and amount of oxirane (propylene or ethylene oxide), the amount of triethylamine catalyst, and the temperature on the reaction with N,N,N′,N′,N′-pentakis (hydroxymethyl) melamine (PHMM) in DMSO solution were studied. The changes in the content of reactive groups in the reaction mixture and in the final product were analyzed. The oxirane addition was shown to be accompanied by the condensation of hydroxymethyl groups in the PHMM. Optimal conditions for the synthesis and the structural formula of the s-triazine ring containing polyetherols were established.

Synthesis of s‐triazine polyetherols from bis(methoxymethyl)melamine and oxiranes

Polyetherols containing s-triazine rings can be obtained in reactions of oxiranes with melamine derivatives. A report on the attempt to replace pentakis(methoxymethyl)melamine with bis(methoxymethyl)melamine in the synthesis is presented. The replacement simplified the procedure by eliminating the stage of transetherification with ethylene glycol. The oxirane addition was carried out without a solvent. The course of the reaction was studied and some properties of the resulting polyetherols determined.

(Hydroxymethyl)melamine-oxirane derived polyetherols: Application of kinetic studies to prediction of synthesis conditions

The study of the kinetics of addition and condensation in the (hydroxymethyl)melamine-oxirane system in DMSO solution and in the presence of triethylamine catalyst is described. The mechanisms of the reactions are presented. The kinetics parameters have been used to optimize the conditions of preparation of the s-triazine ring containing polyetherols from pentakis(hydroxymethyl)melamine and ethylene or propylene oxide.

1H NMR STUDY OF (HYDROXYMETHYL)MELAMINE REARRANGEMENT IN DMSO SOLUTIONS

(Hydroxymethyl)melamines (HMMs) are readily obtained by dissolving melamine in formalin at pH 8-9. They are widely used as precursors of melamine-form-aldehyde resins belonging to an important group of plastics. There are nine HMM isomers possible, with six hydrogen atoms in amino groups of melamine available for substitution. In aqueous solution they form an equilibrium mixture the composition of which was the subject of both theoretical and experimental studies. Each bis-, tris-, and tetrakis(hydroxymethyl)melamine consists of two constituent isomers. The isomers differ in the way the hydroxy-methyl groups are distributed among amino groups.

Preparation and applications of the products of reaction of uric acid with formaldehyde

Abstract Reactions of uric acid (UA) with various amounts of formaldehyde have been studied. At the molar ratio of formaldehyde to uric acid smaller than 6, solid products are formed, at the ratio exceeding 6, the products have the form of resinous substances. The products have been analyzed chemically (acid number, formaldehyde content) and spectrally ( 1 H NMR, IR). Possible applications of the products are pointed out.

The Maillard reaction of bisoprolol fumarate with various reducing carbohydrates

HPLC analysis of drug products containing bisoprolol fumarate and lactose revealed the presence of N-formylbisoprolol, which is a final product of the Maillard reaction. Formulations containing secondary amines and reducing carbohydrates are prone to the condensation of amine and carbonyl functional groups and formation of glycosylamines in pharmaceutically relevant conditions. Further rearrangement occurs in the presence of a nucleophile and leads to the formation of 1-deoxy-1-amino-2-ketose also known as the Amadori Rearrangement Product (ARP). The influence of water content, carbohydrate, and lubricant types on the reaction rate was tested. The reaction progress was monitored by HPLC and UV-Vis spectrophotometry. The structures of intermediates were confirmed by the LC/MS(2) analysis. N-formylbisoprolol - the final reaction product - was synthesised and characterised by LC/MS(2), H(1) and C(13) NMR.

Modification of polyurethane foams with 1,3,5-triazine ring and boron

Boric acid was hydroxyalkylated with glycidol and ethylene carbonate. The product of hydroxyalkylation of boric acid was used to modify oligoetherol obtained from melamine and propylene carbonate. The obtained mixture was further used to get polyurethane foams (PUFs) by reaction with diphenylmethane isocyanate in presence of water. The foaming with diphenylmethane isocyanate containing 30 % tri-functional isocyanates resulted in formation of polyurethane foams of enhanced thermal resistance and diminished flammability in comparison with analogous PUFs based on 1,3,5-triazine ring.