Acrylonitrile
Acrylonitrile
Main page

Acrylonitrile

logo
Community Hub0 subscribers
What are your thoughts?
Be the first to start a discussion here.
Be the first to start a discussion here.
Acrylonitrile

Acrylonitrile is an organic compound with the formula CH2CHCN and the structure H2C=CH−C≡N. It is a colorless, volatile liquid. It has a pungent odor of garlic or onions. Its molecular structure consists of a vinyl group (−CH=CH2) linked to a nitrile (−C≡N). It is an important monomer for the manufacture of useful plastics such as polyacrylonitrile. It is reactive and toxic at low doses.

Acrylonitrile is one of the components of ABS plastic (acrylonitrile butadiene styrene).

Acrylonitrile is an organic compound with the formula CH2CHCN and the structure H2C=CH−C≡N. It is a colorless, volatile liquid although commercial samples can be yellow due to impurities. It has a pungent odor of garlic or onions. Its molecular structure consists of a vinyl group (−CH=CH2) linked to a nitrile (−C≡N). It is an important monomer for the manufacture of useful plastics such as polyacrylonitrile. It is reactive and toxic at low doses.

Acrylonitrile was first synthesized by the French chemist Charles Moureu in 1893. Acrylonitrile is produced by catalytic ammoxidation of propylene, also known as the SOHIO process. In 2002, world production capacity was estimated at 5 million tonnes per year, rising to about 6 million tonnes by 2017. Acetonitrile and hydrogen cyanide are significant byproducts that are recovered for sale. In fact, the 2008–2009 acetonitrile shortage was caused by a decrease in demand for acrylonitrile.

In the SOHIO process, propylene, ammonia, and air (oxidizer) are passed through a fluidized bed reactor containing the catalyst at 400–510 °C and 50–200 kPag. The reactants pass through the reactor only once, before being quenched in aqueous sulfuric acid. Excess propylene, carbon monoxide, carbon dioxide, and dinitrogen that do not dissolve are vented directly to the atmosphere, or are incinerated. The aqueous solution consists of acrylonitrile, acetonitrile, hydrocyanic acid, and ammonium sulfate (from excess ammonia). A recovery column removes bulk water, and acrylonitrile and acetonitrile are separated by distillation. One of the first useful catalysts was bismuth phosphomolybdate (Bi9PMo12O52) supported on silica. Further improvements have since been made.

Various green chemistry routes to acrylonitrile are being explored from renewable feedstocks, such as lignocellulosic biomass, glycerol (from biodiesel production), or glutamic acid (which can itself be produced from renewable feedstocks). The lignocellulosic route involves fermentation of the biomass to propionic acid and 3-hydroxypropionic acid, which are then converted to acrylonitrile by dehydration and ammoxidation. The glycerol route begins with its dehydration to acrolein, which undergoes ammoxidation to give acrylonitrile. The glutamic acid route employs oxidative decarboxylation to 3-cyanopropanoic acid, followed by a decarbonylation-elimination to acrylonitrile. Of these, the glycerol route is broadly considered to be the most viable, although none of these green methods are commercially competitive.

Acrylonitrile is used principally as a monomer to prepare polyacrylonitrile, a homopolymer, or several important copolymers, such as styrene-acrylonitrile (SAN), acrylonitrile butadiene styrene (ABS), acrylonitrile styrene acrylate (ASA), and other synthetic rubbers such as acrylonitrile butadiene (NBR). Hydrodimerization of acrylonitrile affords adiponitrile, used in the synthesis of certain nylons:

Acrylonitrile is also a precursor in the manufacture of acrylamide and acrylic acid.

See all
User Avatar
No comments yet.