High and low molar mass 3‐alkyl‐1,4‐pentazadienes. Synthesis and photolysis

Abstract

High and low molar mass compounds containing the 3-alkyl-1,4-diaryIpentazadiene group were synthesized in the reaction of aromatic diazonium salts with primary amines. These high nitrogen compounds are characterised by high photosensitivity and thermostability. The photolytic decomposition was studied in detail with respect to the substitution at the aromatic moieties and at N3 of the pentazadiene chromophore. Electron donating aromatic substituents were found to increase photosensitivity and decrease thermostability whereas electron withdrawing aromatic substituents cause higher photolytic and thermolytic stability. A little influence of the alkyl group at N3 on the photosensitivity of the pentazadiene group was observed. Photolysis was investigated by means of UV/Vis spectroscopy and obeys first order kinetics for some compounds under investigation. Gel permeation chromatography (GPC) measurements during photolysis of pentazadiene polymers prove that irradiation with UV light causes irreversible chain degradation. Thermolysis in bulk was studied for all compounds by differential scanning calorimetry (DSC). In contrast to the results of the photolysis the alkyl substituent at N3 has an effect on the thermostability of the pentazadiene chromophore.

Pyrolysis of hydrazine derivatives and related compounds with N N single bonds

“…Pentazadienes and hexazadienes are remarkably stable thermally, usually decomposing between 100 and 200 o C. Z-E isomerization of 1,5-diarylpentazadienes 195 has been observed prior to decomposition to aryl and triazenyl radicals (Scheme 56) [183,184].…”

Poly(arylazophosphonate)s: New Arylazophosphonate-Containing Monomers for Synthesis of Laser-Structurable Polymers

“…[10 -12] The same observation was made during the photochemical degradation of the less stable triazenes and pentazadienes. [13,14] Along with the photochemistry, the thermal behavior of azo compounds is a strong criterion for determining the stability of azophosphonates. In the following paragraph we report on the thermal degradation of the azophosphonate-containing monomers.…”

Damped Oscillations in UV−Vis Spectra of Pentazadiene Monomers and Polymers after Laser Photolysis

“…Since then, a wide variety of aromatic 1,4-pentazadiene model compounds and polymers have been synthesized to investigate the influence of the substituents on the photolability. CW photolysis with a HgXe high-pressure lamp and thermolysis behavior have been investigated . It was found that electron donating aromatic substituents increase the photosensitivity and decrease the thermostability.…”