Магния перхлора

Описание

Magnesium perchlorate is a powerful oxidizing agent, with the formula Mg(ClO4)2. Magnesium perchlorate decomposes at 250°C. The heat of formation is 568.90 kJ/mol. If water is added to magnesium perchlorate, the reaction is highly exothermic and may cause damage to the eyes. Thus, this salt should be added to a sufficient amount of water in order to form a dilute solution.
Mg(ClO4)2·6H2O is composed of white, deliquescent crystals which are soluble in water and alcohol but explosive when in contact with reducing materials. This compound is used as a drying agent for gases. This salt is highly exothermic when added to water and releases steamy HCl gas. It can be dried to form the anhydrate by heating to 250°C under vacuum. The hexahydrate losses two molecules of water at 244°C in air and further decomposes to the dihydrate at 336°C and the anhydrate at 438°C.
The anhydrate has been used as a desiccant to dry gas streams or air samples. However, it is no longer used since perchlorates tend to form explosive compounds with a variety of organic materials as well as other substances.

Химические свойства

Magnesium perchlorate is a white crystalline solid.

Использование

Magnesium perchlorate is commonly utilized as a potent oxidizing agent. It is used as dehydrating agent in organic synthesis. It is practiced in many domains like pharma industry, pyrotechnics industry,in rechargeable batteries and it is a versatile tool in organic synthesis. It possesses photoelectronic and optical properties. Thus it can be used in photo electronic and optoelectronic devices. It is applied as a strong drying agent for gases.

Подготовка

Magnesium perchlorate can be prepared by reacting magnesium carbonate with a solution of perchloric acid:
MgCO3＋ HClO4→Mg(ClO4)2＋ CO2
This salt can also be prepared by an electrochemical method in water whereby magnesium perchlorate is formed from magnesium chlorate in which a platinum anode and a rotating stainless steel cathode are employed.

Общее описание

A white crystalline solid. Strongly absorbs water from air and dissolves in it. Accordingly, used as a regenerable drying agent. May explode under prolonged exposure to heat or fire.

Профиль реактивности

Magnesium perchlorate is a strong oxidizing agent. Decomposes at 185-190°C [Hawley]. Noncombustible but accelerates the burning of combustible materials. If large quantities are involved in the fire or the combustible material is finely divided an explosion may result. Avoid contact with mineral acids because of the danger of explosion. In the preparation of anhydrous dimethyl sulfoxide by vacuum distillation from anhydrous Magnesium perchlorate, an explosion occurred [MCA Case History 1187, 1966]. Drying ethylene oxide with Magnesium perchlorate resulted in an explosion [NSC Newsletter. Chem. Soc. 1959]. Magnesium perchlorate used in drying hydrocarbons exploded when heated to 220°C [Ind. & Eng. News 17:70. 1939]. As soon as trimethyl phosphite contacted a small amount of Magnesium perchlorate in a flask, there was a flash and an explosion that shattered the flask [Allison 1968].

Опасность

Dangerous fire and explosion risk in contact with organic materials.

Угроза здоровью

Inhalation of dust irritates mucous membranes. Ingestion of large amounts may be fatal; immediate symptoms include adominal pains, nausea and vomiting, diarrhea, pallor, blueness, shortness of breath, unconsciousness. Contact with eyes or skin causes irritation.

Пожароопасность

Behavior in Fire: Can form explosive mixture with combustible material or finely powdered metals. Increases the intensity of fires.

Профиль безопасности

Moderately toxic by intraperitoneal route. Severe slun and eye irritant. A powerful oxidner which has caused many explosions in industry. Potentially explosive reactions with alkenes (above 22OoC), ammonia, aryl hydrazine + ether, dimethyl sulfoxide + heat, ethylene oxide, fluorobutane + water, organic materials, phosphorus, trimethyl phosphate. Reacts to form explosive products with ethanol (forms ethyl perchlorate), cellulose + dinitrogen tetraoxide + oxygen (forms cellulose nitrate). Avoid contact with mineral acids, but$ fluorides, hydrocarbons. A drying agent. When heated to decomposition it emits toxic fumes of MgO and Cl-. See also MAGNESIUM COMPOUNDS and PERCHLORATES

Возможный контакт

Magnesium perchlorate is used as a drying agent for gases and as an oxidizing agent

Перевозки

UN1475 Magnesium perchlorate, Hazard Class: 5.1; Labels: 5.1-Oxidizer.

Методы очистки

Magnesium perchlorate (Anhydrone, Dehydrite) [10034-81-8 (anhydrous)] M 259.2, m >250o, pK2 5

Несовместимости

A powerful oxidizer. Violent reaction with reducing agents; alkenes (above 220C), ammonia gas; organic matter; ethylene oxide, finely divided or powdered metals, combustible materials, phosphorus, dimethylsulfoxide, mineral acids; wet argon; hydrazines, alcohols, wet fluorobutane; butyl fluorides; organic materials. Forms explosive material with ethyl alcohol. Incompatible with many materials. Shock or heat may cause magnesium perchlorate to explode.