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Methanol

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Methanol
Methanol-2D-flat.png743px-Methanol-3D-vdW.png
General
Systematic name Methanol
Other names hydroxymethane
methyl alcohol
methyl hydrate
wood alcohol
carbinol
Molecular formula CH3OH
SMILES CO
Molar mass 3.204 g/mol3.204 amu
Appearance colorless liquid
CAS number 67-56-1
Properties
Density and phase 0.7918 g/cm30.792 g/ml liquid
Solubility in water Fully miscible
Melting point -97°C176.15 K
-142.6 °F
317.07 °R
(176 K)
Boiling point 64.7°C337.85 K
148.46 °F
608.13 °R
(337.8 K)
Acidity (pKa) 1.5
Viscosity 0.59 cP at 20°C
Dipole moment 1.69 D
Hazards
MSDS Materials Safety Data Sheet
Main hazards Flammable (F)
Toxic (T)
NFPA 704

NFPA 704 svg.png

3
1
0
 
Flash point 11°C
R/S statement R: R11,R23/24/25,R39/23/24/25
S: (S1/2), S7, S16, S36/37,S45
Related compounds
Related alkanols Ethanol
Butanol
Related compounds Chromethane
Methoxymethane
Except where noted otherwise, data are given for
materials in their standard state (at 25 °C, 100 kPa)
Disclaimer and references

Methanol is a colorless, odorless and nearly tasteless alcohol with the simplest chemical structure of all the alcohols. Among all the alcohols, it is the simplest. It is a volatile, colorless, flammable, poisonous liquid with a distinctive odor that is somewhat milder and sweeter than ethanol. At room temperature it is a polar liquid and is used as an antifreeze, solvent, fuel, and as a denaturant for ethyl alcohol.

Methanol is produced by the natural metabolism of many varieties of bacteria. As a result there is a small fraction of methanol vapor in the atmosphere. Methanol burns in air, forming carbon dioxide and water:

2 CH3OH + 3 02 -> 2 CO2 + 4 H20

A methanol flame is colorless, causing an additional safety hazard around open methanol flames. Since methanol has poisonous properties, it is frequently used as a denaturant additive for ethanol manufactured for industrial uses. Methanol is also called wood alcohol because it was once produced chiefly as a byproduct of the destructive distillation of wood. It is now produced by a multi-step process: natural gas and steam are reformed in a furnace to produce hydrogen and carbon monoxide; the hydrogen and carbon monoxide gases react under pressure in the presence of a catalyst to form methanol.

Contents

Properties

The molecular formula for methanol is CH3OH. The molar mass of methanol is 32.04g/mol, the appearance of methanol is a colorless liquid with a density of 0.7918 g/cm3. The melting point of methanol is -97 C (176 K) and its boiling point is 64.7 C (337.8 K). It is fully miscible in water. The dipole moment of methanol is 1.69 D (gas).

Occurrences

Tank of methane

At a high temperature of 850°C, a reaction takes place when methane and steam mix together on a nickel catalyst to produce a gas according to this chemical reaction: [1]

CH4+H2O -> CO+3H2

The result of this reaction is called steam-methane, which is endothermic and requires heat to maintain the reaction, which, in turn, places limitations on the size of the catalytic reactors which can be used. To produce syngas (a flammable mixture of carbon monoxide and hydrogen), methane can undergo partial oxidation with molecular oxygen as the following equation shows:[2]

2 CH4+O2->2CO+4H2

Uses

Methane used as varnisher

Methanol is used in lacquers, paints, varnishes, cements, inks, dyes, plastics and various industrial coatings. It is also used in the production of pharmaceuticals, formaldehyde and other chemical products. Methanol appears as an ingredient in many products, from industrial solvents to windshield-washer fluid and nail-polish remover. It is also used as a fuel. Methanol tastes and smells like common alcohol and has been used as a substitute in illegal alcoholic beverages.

Applications

Cars using methanol

Methanol is a common laboratory solvent. It is useful as a solvent of organic molecules in liquid chromatography [3] where a sample is separated into bands of similar molecules as it travels down through a glass column. It can be used as a solvent for samples that will be tested by ultraviolet spectroscopy [4] due to its transparency to ultraviolet light. Plastic and even glass can absorb ultraviolet light, and make that kind of spectroscopy difficult without a transparent solvent like ethanol or methanol.

Automotive fuel

Methanol has often been seen as a motor fuel substitute during gasoline shortages. In the early 1920s a new way to synthesize methanol was developed and methanol was thought by some to be the best source of automobile fuel. Though methanol gives better power for engines and is used as a fuel in most high performance races, new oil well techniques made gasoline much cheaper to distribute. In World War II europeans widely returned to synthetic methanol as a motor fuel. Methanol was used in several German military rocket designs, under the name of M-Stoff, and also called as C-Stoff [5] [6]

Methanol has several advantages as a motor fuel. It gives about 20% more power though it gets fewer miles per gallon, it is easily formed from natural gas or biomass rather than petroleum, it is easier to form from biomass than ethanol, it is much less polluting because it is a simpler molecule, and as a liquid it can easily displace gasoline in filling stations without much new equipment.[7] Many experts prefer M85 which is 85% methanol and 15% gasoline, which makes the flame visible by daylight, and is somewhat safer.

Methanol is a very good source of fuel for fuel cells which produce electricity. Usually fuel cells require heat to separate the hydrogen from the methanol molecule, but some new technologies use a direct methanol fuel cell (DMFC) where methanol is directly injected into a fuel cell which produces electricity and gives off carbon dioxide.

Safe Handling

A teacher using methanol as class experiment

When working with methanol you must wear safety glasses always. Remove any source of ignition from working area. You should not breathe in the vapour, so it is wise to use a fume cupboard if available. If it is not possible, ensure that the area in which you work is very well ventilated. If methanol has been absorbed, a doctor should be contacted immediately. The toxic effects take hours to start, and the effectiveness of antidotes can often prevent permanent damage.

If methanol is absorbed, the initial symptoms of it would be central nervous system depression giving headaches, dizziness, nausea, lack of coordination, confusion, drowsiness, and with sufficiently large doses, unconsciousness and possible deaths. The symptoms of methanol are usually less severe than the symptoms which results from the quantity of ethyl alcohol. [8] Interestingly, ethanol is a basic antidote for methanol poisoning because the body prefers to process ethanol, giving the kidneys a chance to excrete the methanol before it causes as much damage.

As soon as the initial symptoms have passed, the second set of symptoms arises after 10-30 hours later. It may give blurring or complete loss of vision, together with acidosis. These are the symptoms that results from the causes of the levels of formate in the bloodstream, and this may progress to death by respiratory failure.[9]

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