Thu Jan 20

Types and Synthesis of Isocyanide

Have you come across organic molecules that can fill a room with their unpleasant odor? One of them is isocyanide. Its compounds have a pungent smell that can cause the occupants of a room to seek fresh air immediately. Isocyanide was discovered in 1847 by Lieke. He stated that upon opening a flask full of isocyanide, the room would stink for several days.

Nevertheless, isocyanides are a significant classification of organic compounds. Understanding their properties and structure is fundamental in an organic study.

Let's start by looking into the structure and properties of isocyanide. As an organic compound, isocyanide contains a carbon-nitrogen with a triple bond, with an aryl or alkyl group as part of the nitrogen. It is comprised of two resonance forms. One has a triple bond linking the carbon and nitrogen, while the other, which has an effective resonance contributor, is carbon-nitrogen having a double bond. The linearity of the carbon-nitrogen is almost at 180 degrees bond angle.

How Isocyanides are synthesized.

Dehydrating a Formamide

The most regular method of manufacturing an isocyanide is through dehydrating a formamide. Here, a dehydrating agent is used with diphosgene, phosphoryl chloride, and phosgene compounds. All these play an influential role in activating a transformation. For consideration, look at the synthesis of phenyl isocyanide from formaniline using phosphorylcholine (POCl3) as a dehydrating agent.

Primary Amines

Isocyanides are also made from primary amines, also known as the Hofmann isocyanide synthesis. In this synthesis, chloroform reacts with potassium hydroxide to form a transition known as dichlorocarbene, which goes ahead to react with a primary amine to get isocyanide. That said, it has a significant drawback: the transformation only reacts to primary amines. The Hofmann synthesis can be used to convert phenyl isocyanide with good results.

Halides

A more contemporary synthesis method of producing benzyl isocyanide is combining trimethylsilyl cyanide (TMSCN), salt(silver perchlorate), and benzyl bromide.

Types of Isocyanide

Classes of isocyanates include toluene diisocyanate (TDI), methylene diphenyl diisocyanate (MDI), and hexamethylene diisocyanate (HDI)

Toluene Diisocyanate.TDI

Being a fluid at room temperature, TDI can cause asthma-like symptoms, especially when breathed in when airborne. It is an essential addition in various splash coatings of paint. It is also used to make froths that are a component when manufacturing pads for furniture, cars, and sleeping places.

Methylene Diphenyl diisocyanate (MDI)

When warmed, MDI causes the same asthmatic conditions as TDI when breathed airborne. To a certain degree, MDI is less risky, making it a better choice than TDI in some applications. MDI is generally used in the manufacturing of cement, covered textures, shoe soles, spandex filaments, and vehicle guards. It can as well be found in paint.

Hexamethylene Diisocyanate (HDI)

The primary use of HDI is manufacturing polyurethane froths and coatings. It is also responsible for the hardening of the paint used on cars and airplanes. It can cause asthmatic reactions, including short windedness, hacking cough, and wheezing when it's left in the open.

Other types of isocyanate that are not common include: