Nitrate

Nitrate is a polyatomic ion with the molecular formula NO₃⁻ and a molecular mass of 62.0049 g/mol. Nitrates also describe the organic functional group RONO₂ . These nitrate esters are a specialized class of explosives.

Structure

The anion is the conjugate base of nitric acid, consisting of one central nitrogen atom surrounded by three identically bonded oxygen atoms in a trigonal planar arrangement. The nitrate ion carries a formal charge of -1. This results from a combination formal charge in which each of the three oxygens carries a −²⁄₃ charge, whereas the nitrogen carries a 1+ charge, all these adding up to formal charge of the polyatomic nitrate ion. This arrangement is commonly used as an example of resonance. Like the isoelectronic carbonate ion, the nitrate ion can be represented by resonance structures:

Properties

Almost all inorganic nitrate salts are soluble in water at standard temperature and pressure. A common example of an inorganic nitrate salt is potassium nitrate (saltpeter). A rich source of inorganic nitrate in the human body comes from diets rich in leafy green foods, such as spinach and arugula.

Nitrovasodilator

A nitrovasodilator is a pharmaceutical agent that causes vasodilation (widening of blood vessels) by donation of nitric oxide (NO), and is mostly used for the treatment and prevention of angina pectoris.

This group of drugs includes nitrates (esters of nitric acid), which are reduced to NO in the body. Examples are:

Nitrovasodilators which aren't nitrates include molsidomine and its active metabolite linsidomine, as well as sodium nitroprusside. These substances do not need to be reduced to donate NO.

Medical uses

The nitrates are used for the treatment and prevention of angina and acute myocardial infarction, while molsidomine acts too slowly to be useful for the treatment of acute angina. For quick action in the treatment of angina, glyceryl trinitrate is used in form of a sublingual spray (nitro spray) or as soft capsules to be crunched.