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Expeditious Synthetic Procedure With Improved Economics for UV Transparent Hole Transporting Triarylamine Derivatives

IP.com Disclosure Number: IPCOM000019555D
Publication Date: 2003-Sep-18
Document File: 3 page(s) / 100K

Publishing Venue

The IP.com Prior Art Database

Abstract

A procedure has been developed for TAPC-type hole transport small molecules whose salient feature is the addition of an orthoester to the reaction medium. The product can be isolated in higher yield, in a purer state and in a shorter reaction time, all the while at a lower reaction temperature. Results indicate that the extensive and costly purification protocols usually required to attain electronic grade purity levels for these types of materials may not be necessary.

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Expeditious Synthetic Procedure With Improved Economics for UV Transparent Hole Transporting Triarylamine Derivatives

Blue laser sensitive photoreceptors cannot employ many of the conventional hole transport small molecules since these extensively conjugated materials have significant absorbencies in the spectral blue region.

A procedure has been developed for TAPC-type hole transport small molecules whose salient feature is the addition of an orthoester to the reaction medium. The product can be isolated in higher yield, in a purer state and in a shorter reaction time, all the while at a lower reaction temperature. Results indicate that the extensive and costly purification protocols usually required to attain electronic grade purity levels for these types of materials may not be necessary.

The synthesis is a variant of the Friedel-Crafts reaction which uses strong acid to protonate cyclohexanone and generates a reactive carbonium ion which leads to the first reaction intermediate, a tertiary alcohol. Repetition of this sequence generates another carbonium ion which completes the sequence and leads to product. The reaction mechanism is shown below:

Water is a byproduct of the reaction and we reasoned that if it could be removed effectively, the reaction kinetics could be accelerated by a mass action effect. Of equal importance, water produces a leveling effect on the acidity of the medium and this lowered acidity might not be sufficient to generate the required reactive intermediates. Attempts to remove the water by physical means (i.e., azeotropic distillation) were not effective. In the event, chemical scavenging of the water of reaction produced the desired result. The method chosen to accomplish this was the rapid, acid catalyzed, diffusion-controlled hydrolysis of an orthoes...