Silane

In the narrow sense, it refers to SiH _4. It is also called monosilane to distinguish it from those with silicon numbers of 2 or more. It can also refer to the whole of Si _n H _{2 n +2} , which corresponds to saturated hydrocarbons. Silanes with n = 2 to 4 have been isolated, but those with n greater than that are known to exist. However, they are much more unstable than hydrocarbons. Organosilanes in which these H's are replaced by alkyl or aryl groups are also sometimes called silanes. [ I ] SiH ₄ (32.12). It can be obtained by adding lithium aluminum hydride LiAlH ₄ to silicon dioxide and heating to 150-170 °C, or by reducing silicon tetrachloride SiCl ₄ with LiAlH _4. On a large scale, it can be made by adding alumina Al ₂ O ₃ to SiO ₂ and reducing it with hydrogen at high temperature and pressure. It is a gas with an unpleasant odor. Density 0.68 g cm ^-3 (-185 °C, liquid). Melting point -185 °C, boiling point -112 °C. It is stable at room temperature. Decomposition begins at about 300 °C. The decomposition is accelerated by light. At 400 °C, it completely decomposes into Si and H _2. It ignites at high temperatures in air. When mixed with Cl ₂ , it reacts explosively to produce SiCl _4. It is gradually hydrolyzed with water. It is insoluble in alcohols, ether, CHCl ₃ , etc. It has reducing properties, and reduces CuSO ₄ to Cu ₂ Si and AgNO ₃ to Ag. It is used as a raw material for producing high-purity silicon. [CAS 7803-62-5] [ II ] Si _n H _{2 n +2} ( n ≧ 2). The silane mixture produced by reacting metal silicides such as magnesium silicide Mg ₂ Si with hydrochloric acid is fractionated to obtain compounds with each n . Note that disilane Si ₂ H ₆ with n ≧ 2 can also be produced by photochemical reaction of a gas mixture of SiH ₄ and H ₂ . n = 3: Trisilane, Si ₃ H ₈ . Density: 0.73 g cm ^-3 . Melting point: -117 °C, boiling point: 53 °C. n = 4: Tetrasilane, Si ₄ O ₁₀ . Density: 0.79 g cm ^-3 . Melting point: -84 °C, boiling point: 107 °C. All are soluble in CS ₂ and benzene. They are more unstable than monosilane and disilane, and can be oxidized in air and explode. They also react violently with halogen gases and halogen-containing solvents such as CCl ₄ to form SiCl _4. [ III ] Organosilanes in which the H of silane is replaced with an alkyl or aryl group are much more stable than the hydrides of [ I ] and [ II ]. _{R 4} Si can be obtained by reacting SiCl ₄ with a Grignard reagent (RMgX), LiR, etc. Tetramethylsilane (TMS) (CH ₃ ) ₄ Si is used as the standard for NMR. Poly(organosilane) is cleaved between Si and Si by light, so it is attracting attention as an electronic component and optical functional material.


At around 400 °C, polycarbosilane


When this is heated to nearly 1000°C, it becomes silicon carbide.

Source: Morikita Publishing "Chemical Dictionary (2nd Edition)" Information about the Chemical Dictionary 2nd Edition

狭義では，SiH₄のことをいう．ケイ素数2以上のものと区別するにはモノシランともいう．飽和炭化水素に相当するSi_nH_2n＋2全体をさすこともある．n ＝ 2～4のものは単離されているが，それよりnの大きいものの存在も知られている．ただし，炭化水素よりずっと不安定である．また，これらのHをアルキル基，アリール基などに置換したオルガノシランも，シランということがある．【Ⅰ】SiH₄(32.12)．二酸化ケイ素に水素化アルミニウムリチウムLiAlH₄を加え，150～170 ℃ に加熱するか，四塩化ケイ素SiCl₄をLiAlH₄で還元すると得られる．大規模には，SiO₂にアルミナAl₂O₃を加え，高温・高圧化で水素還元してつくる．不快臭のある気体．密度0.68 g cm^－3(－185 ℃，液体)．融点－185 ℃，沸点－112 ℃．室温では安定である．300 ℃ 付近から分解がはじまる．分解は光で促進される．400 ℃ で完全にSiと H₂ に分解する．空気中で高温では発火する．Cl₂ とまぜると爆発的に反応してSiCl₄を生じる．水で徐々に加水分解する．アルコール類，エーテル，CHCl₃などに不溶．還元性があり，CuSO₄をCu₂Siに，AgNO₃をAgに還元する．高純度のケイ素製造の原料となる．[CAS 7803-62-5]【Ⅱ】Si_nH_2n＋2(n ≧ 2)．ケイ化マグネシウムMg₂Siなどの金属ケイ化物に塩酸を作用させると生じるシラン混合物を分留して，各nの化合物を得る．なお，n ≧ 2のもの(ジシランSi₂H₆)は，SiH₄ と H₂との混合気体の光化学反応でも生じる．n ＝ 3：トリシランSi₃H₈．密度0.73 g cm^－3．融点－117 ℃，沸点53 ℃．n ＝ 4：テトラシランSi₄O₁₀．密度0.79 g cm^－3．融点－84 ℃，沸点107 ℃．いずれも，CS₂，ベンゼンなどに可溶．モノシランやジシランより不安定で，空気中で酸化され，爆発することもある．ハロゲン気体や，CCl₄などの含ハロゲン溶媒ともはげしく反応してSiCl₄になる．【Ⅲ】シランのHをアルキル基またはアリール基で置換したオルガノシランは，【Ⅰ】，【Ⅱ】の水素化物よりずっと安定である．R₄Siは，SiCl₄にグリニャール試薬(RMgX)，LiRなどを反応させると得られる．テトラメチルシラン(TMS)(CH₃)₄SiはNMRの基準に用いられる．ポリ(オルガノシラン)はSi-Si間が光で切断されるので，電子部品や光機能材としても注目されている．


は，400 ℃ 近くでポリカルボシラン


にかわる．これを1000 ℃ 近くに加熱すると，炭化ケイ素になる．

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