Methyl alcohol – the connection relating to group of one-atomic alcohols. Methanol is highly toxic, only 10 ml of this substance are capable to cause severe damage of the central nervous system, a blindness, and 30 ml – death. For this reason there is a need of its identification. It is much simpler to carry out the analysis of methyl alcohol in toxicological laboratory, but it is quite possible to make the simplest definition even in house conditions.
Instruction
1. Methanol is colourless, on a smell and taste we will not distinguish from ethyl alcohol. However qualitatively these substances significantly differ. In this regard there is also a majority of poisonings. If the studied solution contains only one alcohol, then to define what, will be not difficult. But if before you mix of alcohols or alcohol with impurity, then it is possible to learn qualitative and quantitative content only in vitro. For definition of some alcohols (ethanol, glycerin) there is a high-quality reaction – yodoformny test. It will be out very first to confirm or exclude ethanol content in methanol. As a result of conducting test, bright yellow crystals of a triyodmetan (iodoform) drop out in a deposit. Methanol does not give this reaction. C₂H₅OH + J ₂ + NaOH = CHJ ₃↓ + NaJ + HCOONa + H₂O
2. Many high-quality reactions to methyl alcohol are based on its transformation into methyl aldehyde (formaldehyde). Pour solution in a test tube with an exhaust tube, add potassium permanganate in the presence of sulfuric acid. As a result of an otgonka, formaldehyde which it is possible to affect with various reactants is formed. Permanent violet coloring, hromotropovy acid – violet coloring of solution, potassium hexacyanoferrate – blue-violet coloring, a reactant of Fellinga – a black deposit gives Schiff's reactant. These reactions are confirming on methanol.
3. In house conditions the research can be conducted by means of a copper wire. Heat it over fire and lower in the studied solution. If it contained methanol, then the formalin smell - sharp and very unpleasant will appear. With ethanol such effect will not be. Quantitative determination of content of methanol is carried out in vitro by titrimetrichesky methods and gas-liquid chromotography.