What is the Difference Between Cyanide and Isocyanide

The key difference between cyanide and isocyanide is that cyanide compounds have a CN group attached to the organic moiety through the carbon atom, whereas isocyanide compounds have a CN group attached to the organic moiety through the nitrogen atom.

Cyanide and isocyanide are isomers of each other. This is the way the name isocyanide is derived from cyanide with the prefix “iso-.” These are often toxic substances.

CONTENTS

1. Overview and Key Difference
2. What is Cyanide  
3. What is Isocyanide
4. Cyanide vs Isocyanide in Tabular Form
5. Summary – Cyanide vs Isocyanide

What is Cyanide?

Cyanide is any chemical compound having a cyano (C≡N) group. The cyano group has a carbon atom and a nitrogen atom, which are linked via a triple bond. Thus, the term cyanide may refer to any organic or inorganic compound containing a cyano group. In contrast, the term nitrile refers to any organic compound having a cyano group.

Figure 01: Cyanide

Usually, in inorganic cyanides, the cyano group is present as an anion, for example, sodium cyanide and potassium cyanide. Moreover, these cyanides are highly toxic. Hydrogen cyanide or HCN is a highly volatile and highly toxic substance. In nitriles, the cyano group is attached with a covalent bond to the rest of the molecule (not as an ion). A common example would be acetonitrile.

Moreover, cyanides are produced by many bacteria, fungi, and algae species. Cyanide is also a common component in many plants. Furthermore, these compounds form as a byproduct of combustion in an oxygen-deficient environment.

When considering the applications of cyanides, these compounds are useful in mining for silver and gold because cyanides help to dissolve these metals. Furthermore, cyanides are important as precursors for the organic synthesis processes, e.g., the production of nylon. Besides, there are applications of cyanide in the field of medicine and pest control.

What is Isocyanide?

Isocyanides are organic compounds having the functional group -N≡C.  The term isocyano originates from the relative isomer, nitrile group(-C≡N), which is named as cyano group. This organic chemical moiety is linked to the isocyanide group via a nitrogen atom in this functional group. Isocyanide compounds are important in the synthesis of other compounds, where they act as building blocks.

There are two resonance structures possible for isocyanide molecules. One resonance structure has a triple bond between carbon and nitrogen atoms, while the other resonance structure has a double bond between carbon and nitrogen atoms.

Figure 02: An Example of an Isocyanide, Xanthocillin

One of the most characteristic features of isocyanide is its odor that is a penetrating, extremely unpleasant odor. Moreover, some isocyanide compounds can be toxic, e.g. cyclohexyl isocyanide. However, other isocyanides do not show considerable toxicity in mammals.

There are several different ways of producing isocyanides, which include the production from formamides, dichlorocarbene, silver cyanide route, etc. Among them, the most common method is the production from formamide, which involves the dehydration of formamides.

What is the Difference Between Cyanide and Isocyanide?

Cyanide and isocyanide are isomers of each other. This is the way the name isocyanide is derived from cyanide with the prefix “iso-. “ These are often toxic substances. The key difference between cyanide and isocyanide is that cyanide compounds have a CN group attached to the organic moiety through the carbon atom, whereas isocyanide compounds have a CN group attached to the organic moiety through the nitrogen atom.

The below infographic presents the differences between cyanide and isocyanide in tabular form for side by side comparison.

Summary – Cyanide vs Isocyanide

The key difference between cyanide and isocyanide is that cyanide compounds have a CN group attached to the organic moiety through the carbon atom, whereas isocyanide compounds have a CN group attached to the organic moiety through the nitrogen atom.