Hydroxylamine

[ I ] Hydroxylamine: _NH2OH (33.03). It is prepared from a salt. For example, it can be obtained by reacting [ _NH3OHCl ] with Na( _OC2H5 ) in ethanol, or with _Na3PO4 to form the phosphate, _which is then thermally decomposed under reduced pressure. It exists in both cis and trans forms as shown in the figure (it is _unknown whether the gauche form exists). In the solid state, only the trans form exists, while in the gas state, both are mixed. The solid form is a colorless monoclinic crystal.

Density: approximately 1.20 g cm ^-3 (0°C). NO: approximately 1.47 Å, OH: approximately 0.97 Å, NH: approximately 1.03 Å. ∠HON: approximately 102°, ∠HNO: approximately 107°, ∠HNH: approximately 107°. Melting point: 33°C, boiling point: 142°C (partially decomposed; 57°C at 22 mmHg). Deliquescent and volatile. Decomposes slowly even at room temperature, but this is accelerated by moisture and _CO2 . Decomposition also progresses rapidly when heated (to _NH3 , _N2 , _N2O , etc.). Easily soluble in water, liquid ammonia, and methanol, and sparingly soluble in ether, benzene, chloroform, etc. In aqueous solutions,

NH ₂ OH + H ₂ O → NH ₃ OH ⁺ + OH ^-

It dissociates into ions as shown below. pKb _is approximately 7.9. It reacts with acids to form salts. As a solvent, it dissolves alkali metal and alkaline earth metal salts. It has strong reducing properties. It is used in organic synthesis as a reducing agent and for addition reactions. It is toxic. [CAS 7803-49-8] [ II ] Hydroxylammonium salt: [ _NH3OH ] ⁺ X- ^. Representative examples include chlorides and sulfates.
(1) Hydroxylammonium sulfate: (NH ₃ OH) ₂ SO ₄ (164.14). Also known as hydroxylamine sulfate. It can be obtained by the reaction between (NH ₄ ) ₂ SO ₃ , NH ₄ NO ₂ and SO ₂ , by hydrolysis of nitroparaffin with sulfuric acid, or by electrolytic reduction of nitric acid with sulfuric acid. Colorless monoclinic crystal. Ionic crystal containing [NH ₃ OH] ⁺ . Melting point 170 °C (decomposition). Easily soluble in water (aqueous solution is strongly acidic), insoluble in ethanol and ether. Strong reducing agent, damages metals and skin. Used as a synthetic drug, reducing agent, etc. Toxic. [CAS 10039-54-0].
(2) Hydroxylammonium chloride: [NH ₃ OH]Cl (69.49). Also called hydroxylamine chloride. It can be obtained by electrolytic reduction of nitric acid followed by reaction with HCl or by reacting an aqueous solution of (NH ₃ OH) ₂ SO ₄ with BaCl _2. Colorless monoclinic crystal. Ionic crystal containing [NH ₃ OH] ⁺ . Density: about 1.68 g cm ^-3 . NO: about 1.45 Å, N...Cl: about 3.16, 3.21, 3.23 Å. Melting point: 152 °C (decomposition). Decomposes gradually in humid air. Easily soluble in water and liquid ammonia, soluble in methanol and ethanol, insoluble in ether. Decomposes gradually in aqueous solution. Has reducing properties. Forms ketones, aldehydes and oximes. Used as a raw material for hydroxylamine, synthesis and analytical reagent. It is also used as a photographic reducing agent, soap, antioxidant for fatty acids, and enzyme reactivator. [CAS 5470-11-1]

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

【Ⅰ】ヒドロキシルアミン：NH₂OH(33.03)．塩からつくる．たとえば，[NH₃OHCl]を，Na(OC₂H₅)とエタノール中で反応させるか，Na₃PO₄と反応させてリン酸塩とし，これを減圧下熱分解すると得られる．図のようなシス，トランスの両形がある(なお，ゴーシュ形の存否は不明)．固体ではトランス形のみ，気体では両者が混在している．固体は無色の単斜晶系結晶．

密度約1.20 g cm^－3(0 ℃)．N-O約1.47 Å，O-H約0.97 Å，N-H約1.03 Å．∠H-O-N約102°，∠H-N-O約107°，∠H-N-H約107°．融点33 ℃，沸点142 ℃(一部分解．22 mmHg では，57 ℃)．潮解性，揮発性がある．室温でも徐々に分解するが，湿気やCO₂で促進される．また，加熱すると急速に分解が進む(NH₃，N₂，N₂Oなどになる)．水，液体アンモニア，メタノールに易溶，エーテル，ベンゼン，クロロホルムなどに難溶．水溶液中では，

NH₂OH ＋ H₂O → NH₃OH^＋ ＋ OH^－

のように解離してイオンになる．pK_b 約7.9．酸と反応して塩となる．溶媒として，アルカリ金属やアルカリ土類金属の塩を溶かす．強い還元性がある．有機合成で，還元剤，付加反応用などに用いられる．有毒．[CAS 7803-49-8]【Ⅱ】ヒドロキシルアンモニウム塩(hydroxylammonium salt)：[NH₃OH]^＋ X^－．とくに塩化物，硫酸塩などが代表例．
(1)硫酸ヒドロキシルアンモニウム：(NH₃OH)₂SO₄(164.14)．硫酸ヒドロキシルアミン(hydroxylamine sulfate)ともいう．(NH₄)₂SO₃，NH₄NO₂およびSO₂間の反応や，ニトロパラフィンに硫酸を加えて加水分解するか，硝酸に硫酸を加え電解還元すると得られる．無色の単斜晶系結晶．[NH₃OH]^＋ を含むイオン結晶．融点170 ℃(分解)．水に易溶(水溶液は強酸性)，エタノール，エーテルに不溶．強還元剤，金属や皮膚をおかす．合成用薬剤，還元剤などに用いられる．有毒．[CAS 10039-54-0]．
(2)塩化ヒドロキシルアンモニウム：[NH₃OH]Cl(69.49)．塩酸ヒドロキシルアンモニウム(hydroxylamine chloride)ともいう．硝酸を電解還元後，HClを反応させるか，(NH₃OH)₂SO₄水溶液にBaCl₂を作用させると得られる．無色の単斜晶系結晶．[NH₃OH]^＋ を含むイオン結晶．密度約1.68 g cm^－3．N-O約1.45 Å，N…Cl約3.16，3.21，3.23 Å．融点152 ℃(分解)．湿気のある空中では徐々に分解する．水，液体アンモニアに易溶，メタノール，エタノールに可溶，エーテルに不溶．水溶液中でしだいに分解していく．還元性がある．ケトン，アルデヒドとオキシムをつくる．ヒドロキシルアミンの原料，合成，分析用試薬に用いられる．そのほか，写真用還元剤，せっけん，脂肪酸の酸化防止剤，酵素の再活性化剤などにも用いられる．[CAS 5470-11-1]

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