Esters are derivatives of alcohols in whose molecules the OH atom of the OH group is replaced by a carbon radical. Esters are characterized by metamerism and isomerism of the hydrocarbon chain.
The isomerism of a hydrocarbon chain is due to its branching.
Metamerism is a type of isomerism in which two or more esters have a similar molecular formula, but different molecular structures, due to different radicals on either side of the oxygen “bridge”. For example, three esters correspond to the molecular formula C4H10O:
- CH3-O-CH (CH3) 2;
- CH3-O-C3H7;
- C2H5-O-C2H5.
These substances are obtained synthetically, including dimethyl ether. The formula of this compound is represented by two methyl radicals that are linked by an oxygen “bridge”.
It should be noted that in nature ethers in a free state do not occur. Dimethyl and methylethyl ethers are gases. The next few representatives are liquids, while higher esters are solids. They are very poorly soluble in water, excellent in organic solvents. The average representatives (dipropyl, propylethyl, diethyl) are excellent organic solvents. The physical properties of these organic compounds vary with molecular weight.
Dimethyl ether: preparation
The described substance is highly soluble in water, ethanol, diethyl and dipropyl ethers. This ether is obtained due to the dehydration of methanol and as a by-product of the production of methanol from H2 and CO. Used in refrigeration units as a refrigerant.
In the near future, diesel engines will not be converted to gas, but to dimethyl ether. Such reconstruction will cost them much cheaper compared to switching to natural gas. The leading countries for the production of such engines are the United States, Russia and Japan.
At the beginning of the 21st century, the Russian government decided to use alternative fuels in vehicles. Dimethyl ether is used on trucks. This cardinal decision was made due to the fact that emissions of nitrogen compounds from diesel engines installed on trucks exceed the established standards by several times. Dimethyl ether is ideal for this type of engine, they practically do not need to be reconstructed. Only through the use of a new alternative type of fuel did the new modernized engines reach the level of environmental friendliness of Euro-3.
The governments of many countries of the world are sure that dimethyl ether will be the fuel of the future for diesel engines. Today, this substance is obtained mainly by processing natural gas. In the early stages of the process, natural gas is reformed, resulting in synthesis gas. After that, it turns into methyl alcohol. Further, methanol is amenable to dehydration, resulting in dimethyl ether. There is another method for the synthesis of this ether - direct conversion of synthesis gas to methanol.
Ethers in comparison with diesel fuel have their advantages and, of course, disadvantages. There are no “carbon-carbon” bonds in the structure of the ether molecule. Due to the significant oxygen content, good atomization is ensured by injecting ether into the medium with a temperature above the boiling point of the substance itself. These characteristics improve fuel combustion. Due to the use of this alternative fuel , the engine noise level is reduced, while its reliability is increased.
The main disadvantages of this ether include lower calorific value and lower density. All this leads to an increase in fuel consumption. This substance has very poor lubricating properties.