Dirk Armand Wim Stanssens

Synthesis of 1,2-bis(2-oxazolinyl-2)ethane and its application as chain extender for poly(ethylene terephthalate)

SummaryThe reaction of ethanolamine (EA) with nitriles is a general route to prepare oxazolines. However, in case of vicinal nitrile groups, cyclic imidines are formed. It is shown, that succinonitrile gives with EA mainly 1-(hydroxyethyl)-2,5-bis-(hydroxyethylimine) azacyclopentane (= triol). The corresponding 1,2 bis-(2-oxazolinyl-2) ethane (BOXE) is formed by heating the triol. BOXE can be used as chain extender of poly(ethylene terephthalate) (PET). If PET is heated with BOXE at 270 °C the viscosity increases first. However, on prolonged heating the viscosity decreases again, which can not be ascribed to the normal degradation processes. Therefore, a mechanism is proposed in which the chain scission takes place in the newly formed bridge.

(S)-3,3-Dimethyl-1,2,4-butanetriol as Ligand for Titanium Catalysed Asymmetric Silylcyanation

Trimethylsilylcyanation of benzaldehyde was effected in up to 76% e.e. using a catalyst prepared from the triol obtained by reduction of D-Pantolactone and titanium isopropoxide.

The aliphatic oxirane powder coating system: development, crosslinking chemistry and coating properties

Powder paints based on the new aliphatic oxirane binder system (Uranox) do not require hazardous-chemical labelling and meet the most stringent regulations concerning health, safety and the environment. The new system features a complete binder based on a polyester resin and an aliphatic oxirane crosslinker. This unique approach and the new crosslink chemistry of the binder make this system an important innovation in the global powder coating business. The development that has lead to the oxirane binder is described. After the synthesis and screening of several glycidyl compounds, the disubstituted aliphatic epoxides were selected for application in the new system. An extensive study on the crosslinking of the new binder has been carried out. It was found that special catalysis is necessary to obtain good conversion and, concomitantly, good coating properties. Finally the properties, handling characteristics and performance of aliphatic oxirane-based powder coating systems are discussed. In addition, a very efficient matting agent is described which has been specially developed for the aliphatic oxirane binder system. This matting agent enables the gloss of aliphatic oxirane-based powder coatings to be reduced to any desired level.

On the mechanism of the esterification of a β-hydroxy alkylamide with a carboxylic acid

β-Hydroxy alkylamide reacts with carboxylic acid to form an ester much faster than with a normal alcohol. Many suggestions have been made to describe the mechanism of this reaction, but none of them have been proved. It is clear that this reaction cannot be seen as a normal esterification since it cannot be catalysed by acids or bases. We have prepared model compounds, for which calibration curves have been obtained by means of UV spectroscopy. A technique was developed for separating the starting materials and the expected reaction products by means of HPLC. In this way, quantitative and qualitative information about the reaction mixtures could be obtained as a function of time. This method revealed the existence of an intermediate oxazolinium cation. The formation of this compound plays a key role in the esterification. Apart from the expected ester and the intermediate, various other reaction products were determined. All the reaction products could be obtained in a pure state with the aid of preparative HPLC. The structures of the compounds were studied using 1H NMR spectrometry. A reaction mechanism has been put forward to explain the experimental data.