ESTERIFICATION BASIC INFORMATION AND TUTORIALS

A variety of solvents, monomers, medicines, perfumes, and explosives are made from esters of nitric acid. Ethyl acetate, n-butyl acetate, iso-butyl acetate, glycerol trinitrate, pentaerythritol tetranitrate (PETN), glycol dinitrate, and cellulose nitrate are examples of such reactions.

Ester manufacture is a relatively simple process in which the alcohol and an acid are heated together in the presence of a sulfuric acid catalyst, and the reaction is driven to completion by removing the products as formed (usually by distillation) and employing an excess of one of the reagents. 

In the case of ethyl acetate, esterification takes place in a column that takes a ternary azeotrope. Alcohol can be added to the condensed overhead liquid to wash out the alcohol, which is then purified by distillation

and returned to the column to react.

Amyl, butyl, and iso-propyl acetates are all made from acetic acid and the appropriate alcohols. All are useful lacquer solvents and their slow rate of evaporation (compared to acetone or ethyl acetate) prevents the surface of the drying lacquer from falling below the dew point, which would cause condensation on the film and a mottled surface appearance (blushing). 

Other esters of importance are used in perfumery and in plasticizers and include methyl salicylate, methyl anthranilate, diethyl-phthalate, dibutyl-phthalate, and di-2-ethylhexyl-phthalate.

Unsaturated vinyl esters for use in polymerization reactions are made by the esterification of olefins. The most important ones are vinyl esters: vinyl acetate, vinyl chloride, acrylonitrile, and vinyl fluoride. The addition reaction may be carried out in either the liquid, vapor, or mixed phases, depending on the properties of the acid. 

Care must be taken to reduce the polymerization of the vinyl ester produced. Esters of allyl alcohol, e.g., diallyl phthalate, are used as bifunctional polymerization monomers and can be prepared by simple esterification of phthalic anhydride with allyl alcohol. 

Several acrylic esters, such as ethyl or methyl acrylates, are also widely used and can be made from acrylic acid and the appropriate alcohol. The esters are more volatile than the corresponding acids.

WHY DOES SALT WATER MAKE METAL RUST FASTER?

If you had pure iron and put it into pure water, very little would happen, since there would be no oxygen to react with the iron. And if you put the pure iron into pure dry oxygen, very little would also happen.

The outer iron atoms would rust, but then that layer of rust would stand between the iron and the remaining oxygen.

Water helps iron react with oxygen. The first step in getting oxygen to react with iron is to break up the oxygen molecule. In water, oxygen can steal some electrons from iron to make four hydroxyl ions (the OH− ions in the following reaction):

O2 + 4 e− + 2 H2O ! 4 OH−

The electrons come from the iron:
Fe ! Fe2+ + 2 e−
Diethylene glycol
O
O
O
H H

But to make rust we need another reaction with iron:
4 Fe2+ + O2 ! 4 Fe3+ + 2 O2
−
In the process of making rust, the ferrous (Fe2+) and ferric (Fe3+) ions also react with water to form Fe(OH)2 and Fe(OH)3 (ferrous hydroxide and ferric hydroxide) and hydrogen. These hydroxides can then lose their water to form still more iron compounds.

It is all these reactions that end up making the rust flaky, so it falls off the iron and exposes new iron that can start to rust.

All of these reactions are sped up by acids and by having more ions in the water, so it conducts electricity better, so that the iron and oxygen can exchange electrons. Adding salt to the water makes the iron corrode more quickly, but adding an acid makes it corrode even faster than that.