定义Definition
一氧化氮 NO 是无色气体，分子含一个未成对电子，是稳定的自由基。它在空气中迅速被氧化为红棕色的 NO₂。NO 是汽车尾气中的污染物，也是生物体内重要的信号分子。
Nitric oxide, NO, is a colourless gas whose molecule has one unpaired electron, making it a stable radical. In air it is quickly oxidised to red-brown NO₂. NO is a pollutant in vehicle exhaust and also an important signalling molecule in living things.
生成与反应Formation and reactions
高温下（内燃机、闪电）氮气与氧气化合：N₂ + O₂ → 2NO，ΔH = +181 kJ mol⁻¹。实验室用铜与稀硝酸反应制取，用排水法收集。NO 遇空气：2NO + O₂ → 2NO₂。汽车催化转化器把它还原：2NO + 2CO → N₂ + 2CO₂。
At high temperature, in engines and lightning, nitrogen and oxygen combine: N₂ + O₂ → 2NO, ΔH = +181 kJ mol⁻¹. In the laboratory it is made from copper and dilute nitric acid and collected over water. In air, 2NO + O₂ → 2NO₂. Catalytic converters reduce it: 2NO + 2CO → N₂ + 2CO₂.
生物学作用In biology
人体血管内皮细胞产生的 NO 能使血管平滑肌松弛、血管扩张，参与调节血压，也在神经传递和免疫中发挥作用。硝酸甘油治疗心绞痛就是通过在体内释放 NO 起效。
NO made by the cells lining blood vessels relaxes the smooth muscle and widens the vessels, helping control blood pressure, and it also acts in nerve signalling and immunity. Nitroglycerine relieves angina by releasing NO in the body.
化学性质Chemical properties
与氧气反应：2NO + O₂ → 2NO₂
With oxygen: 2NO + O₂ → 2NO₂
在催化转化器中被 CO 还原：2NO + 2CO → N₂ + 2CO₂
Reduced by CO in a catalytic converter: 2NO + 2CO → N₂ + 2CO₂
作配体与过渡金属形成亚硝酰配合物
Acts as a ligand, forming nitrosyl complexes with transition metals
年表Timeline
- 1772
普里斯特利制得一氧化氮
Priestley prepares nitric oxide
- 1987
研究证实血管内皮舒张因子就是 NO
The endothelium-derived relaxing factor is identified as NO
- 1998
弗奇戈特、伊格纳罗、穆拉德因 NO 的信号作用获诺贝尔生理学或医学奖
Furchgott, Ignarro and Murad receive the Nobel Prize in Physiology or Medicine for NO signalling