Silicon tetrahydride

Описание

Silane is a colorless, spontaneously flammable (pyrophoric) gas. It has a choking odor and may form explosive mixtures with air. Silane will react violently with heavy metal halides and free halogens other than hydrogen chloride.

Химические свойства

Silicon tetrahydride is a highly toxic gas with a repulsive odor. It is spontaneously flammable in air. Trichlorosilane has an acrid odor, fumes in air and supports combustion. It is a lachrymator and is moisture sensitive. Octamethyl tetrasilane is moisture sensitive.

Использование

Source of hyperpure silicon for semiconductors.

Определение

ChEBI: The simplest silane, consisting of a single silicon atom carrying four hydrogens.

Общее описание

Silicon tetrahydride is a colorless, flammable and poisonous gas, with a strong repulsive odor. Silicon tetrahydride is easily ignited in air, reacts with oxidizing agents, is very toxic by inhalation, and is a strong irritant to skin, eyes and mucous membranes. Silicon tetrahydride is lighter than air. Under prolonged exposure to fire or heat the containers may rupture violently and rocket. Silicon tetrahydride is used in the production of amorphous silicon.

Реакции воздуха и воды

Highly flammable. Pure state ignites in air, the first seven to eight of the series 6H2n+1 ignite spontaneously in air at room temperature or slightly elevated temperatures [Mellor 1:376 1946-47]. Slowly reacts with water to form silicon hydroxides and hydrogen gas.

Профиль реактивности

Slowly reacts with water to form silicon hydroxides and hydrogen gas [Hydrides of the Elements of Main Groups I - IV 1971 p.513]. Silicon tetrahydride burns in contact with bromine, chlorine or covalent chlorides (carbonyl chloride, antimony pentachloride, tin(IV) chloride). Even traces of the free halogens may cause violent explosions, when handling Silicon tetrahydride, extreme caution should be taken, [Mellor, 1940, Vol. 6, 220]. Mixtures of Silicon tetrahydride and nitrogen oxides, nitrous oxide, detonate very easily, [Chem. Abs., 1990, 112, 121711].

Опасность

Dangerous fire risk, ignites spontaneously in air. Strong irritant to tissue, skin and upper res- piratory tract.

Угроза здоровью

Vapors may cause dizziness or asphyxiation without warning. Some may be toxic if inhaled at high concentrations. Contact with gas or liquefied gas may cause burns, severe injury and/or frostbite. Fire may produce irritating and/or toxic gases.

Пожароопасность

EXTREMELY FLAMMABLE. Will be easily ignited by heat, sparks or flames. Will form explosive mixtures with air. Silicon tetrahydride will ignite spontaneously in air. Vapors from liquefied gas are initially heavier than air and spread along ground. Vapors may travel to source of ignition and flash back. Cylinders exposed to fire may vent and release flammable gas through pressure relief devices. Containers may explode when heated. Ruptured cylinders may rocket.

Контактные аллергены

Various silane derivatives are used as bonding agents between glass and the resin used as a coating agent of glass filaments. Organosilanes have been implicated as sensitizers in workers at a glass filament manufactory.

Использование в материалах

Piping and equipment for silane service may be of steel or stainless steel construction. Piping and equipment must be designed to withstand the pressures involved. Extreme care must be taken to avoid the contact ofsilane with materials containing heavy-metal halides or free halogens. Silane will react violently or explosively with these compounds.
Silane systems should be purged of air to prevent silane ignition and contamination with silicon dioxide. All systems to handle silane should be designed with the following factors in mind:
? Prevention of leakage, both in and out, under vacuum and pressure
? Minimum necessary internal volume
? Elimination of dead spaces
? Isolation ofsystem components in case of a leak, rupture, or other failure
? Ability to easily evacuate and purge the system and components with inert gas
? That silane should never be purged through a vacuum pump
? The use offittings preferably ofthe welded face seal gasketed type to minimize the likelihood ofleaks
? Use of diaphragm packless valves with resilient seats such as Kel-F
? The removal of backplates from gauges and rotometers where gases may collect upon leakage to allow pressure venting away from personnel if an explosion takes place
? The use ofmetal diaphragm regulators to minimize air diffusion leakage Consideration ofthe use offlow restrictions in cylinder valves.

Профиль безопасности

Mildly toxic by inhalation. Silanes are irritating to skin, eyes, and mucous membranes. Easily ipted in air. Explosive reaction or ignition on contact with halogens or covalent halides (e.g., bromine, chlorine, carbonyl chloride, antimony pentachloride, tin(Iv> chloride). Ignites in oxygen. Can react with oxidizers. It may self-explode. When heated to decomposition it burns or explodes.

Возможный контакт

Silane is used as a doping agent for solid-state devices; as a source of silicon for semiconductors; and in the production of amorphous silicon.

Экологическая судьба

Silane is a colorless transparent gas, heavier than air. It is odorless when greatly diluted, but extremely noxious when concentrated, with a sharp, repulsive smell, somewhat similar to that of acetic acid. Its silicon–hydrogen bond is much weaker, and accordingly more reactive, than a carbon– hydrogen single bond. It is not only inflammable in air at concentrations between 1% and 96% v/v, producing particulate silicon oxides and hydrogen gas, but is pyrophoric. Above 420°C silane decomposes, releasing hydrogen and depositing high-purity silicon, which leads to some of its principal applications. It also reacts avidly with oxidants; for example, contact with even trace amounts of free halogens may cause violent explosions. It is insoluble in water, and does not react with water under normal conditions, but in the presence of even minute traces of hydroxyl ion reacts to evolve hydrogen gas and form corrosive silicic acid or hydrated silicon dioxide. The reaction with water is further accelerated by organic or inorganic bases. Silane is fully biodegradable, and will not bioaccumulate.

Перевозки

UN2203 Silane, Hazard Class: 2.1; Labels: 2.1-Flammable gas. Cylinders must be transported in a secure upright position, in a well-ventilated truck. Protect cylinder and labels from physical damage. The owner of the compressed gas cylinder is the only entity allowed by federal law (49CFR) to transport and refill them. It is a violation of transportation regulations to refill compressed gas cylinders without the express written permission of the owner.

Несовместимости

An extremely flammable gas. Forms explosive mixture with air; may spontaneously ignite in air. A strong reducing agent. Reacts slowly with water forming silicon hydroxides and flammable hydrogen gas. Reacts with oxidizing agents; halogens , potassium hydroxide solution. Explodes in oxygen. Decomposes on heating or on burning producing silicon and hydrogen.

Утилизация отходов

Return refillable compressed gas cylinders to supplier. Dispose by controlled burning or seal cylinders and return to suppliers.