Acrylonitrile

Brief Overview
Acrylonitrile, also known as vinyl cyanide, is a clear, colourless, liquid with a strong pungent odour and it has a chemical formula of H2CH(CH)CN. At times, it may appear as pale yellow liquid due to the presence of impurities. It is miscible with water and various common organic solvents such as ethanol, acetone, benzene and ether. Being a reactive chemical, it will polymerise spontaneously upon heating and can even explode on contact with flames. Acrylonitrile may also decompose to form free cyanide at elevated temperatures and emit toxic fumes of nitrogen oxides and cyanides.
Acrylonitrile is not found naturally in the environment but it is present in trace amounts at industrial sites. In the air, it will decompose by reacting with oxygen and hydroxyl radical to produce formyl cyanide and formaldehyde.
Acrylonitrile attacks copper and is incompatible with strong oxidisers such as acids, alkalis, bromines, and amines.
Manufacturing Process
Acrylonitrile is typically obtained through the catalytic ammoxidation of propylene where ammonia, propylene and air is reacted with the aid of a catalyst (phosphorus molybdenum bismuth or antimony iron-based) in a fluidised bed. Silica gel is used as a carrier with the reaction carrying out at 400 -500oC at normal pressure. The mixture is passed through a neutralisation tower and dilute sulfuric acid is added to remove the basic unreactive ammonia. Water is passed through the absorption tower to extract the acrylonitrile gas and this gives an aqueous solution. The aqueous solution passed through the extraction tower to isolate the desired product, acrylonitrile. The acidic hydrogen cyanide which is produced as a side product in this reaction is removed in the dehydrocyanide tower and the resulting mixture went through dehydration and rectification to finally obtain the acrylonitrile products with a yield of approximate 75%. This industrial synthesis is by far the most common and preferred way to obtain acrylonitrile.