Highly conjugated energetic salts exhibit remarkable thermostability and insensitivity.

New polynitrostilbenes were directly synthesised by the Knoevenagel condensation of aromatic aldehydes with nitrotoluenes. The differential scanning calorimetry results demonstrated that the introduction of an amino group and C=C double bonds could improve the thermal stability.

A microwave-assisted method for the synthesis of polynitrostilbenes involving the condensation of 2,4,6-trinitro-m-xylene and 2,4,6-trinitrotoluene with aryl aldehydes in the presence of piperidine and silica-gel is reported. Compared with conventional methods, a shorter reaction time is required and this method has a lower environmental impact. A mechanism for the reaction is also proposed and supported by UV-Vis absorption spectroscopy.Polynitrostilbenes, such as 2,2 ′ ,4,4 ′ ,6,6 ′ -hexanitrostilbene (HNS) 1-3 are well known explosives with excellent thermal stability and detonation properties. Nitrostilbene-based compounds are also widely used as organic nonlinear optical materials 4-9 for high-performance electro-optical devices. The Mizoroki-Heck reaction, Negishi-Stille coupling and Wittig-type reactions have proved to be quite versatile in the preparation of different substituted stilbenes. However, they need transition-metal catalysis and complicated sequences to form halogen-and phosphorus-containing substrates. [10][11][12][13][14][15] More recently, transition metal catalysts especially palladium have been widely studied in stilbene syntheses. Other methods include the McMurry coupling and alkene cross-metathesis as well as one-pot multicatalytic processes. [16][17][18][19] These sometimes lacked stereoselectivity and the cost was increased by using noble metals. We have reported 20 that 2,4,6-trinitro-m-xylene (TNMX) will condense with two equivalents of aromatic aldehydes in boiling benzene with a piperidine catalyst. The whole process was time-consuming but proceeded with high stereoselectivity.Recently, microwave-assisted organic synthesis (MAOS) has developed into a popular branch of synthetic organic chemistry, 21-25 as it helps in minimising the energy consumption required for heating as well as the time required for the reaction. However, a combination of microwave and solvent-free conditions are rare in polynitrostilbene chemistry. We now report a useful and solvent-free method for the synthesis of an array polynitrostilbenes based on TNMX and 2,4,6-trinitrotoluene (TNT) with piperidine catalysis utilising microwave irradiation. To make the system safer, silica-gel was used as an effective solid support. In order to shed more light on this reaction, the mechanism of the reaction was also studied by UV-Vis absorption.

Polynitrostilbenes are prepared from 2,4,6‐trinitro‐m‐xylene and 2,4,6‐trinitrotoluene by a microwave‐assisted solvent‐free method.