每周分子 | Molecule of the Week

Original ACS 美国化学会 ACS美国化学会 2022-07-01

收录于合集 #每周分子 110个

每周分子：氨

Molecule of the Week: Ammonia

氨是一种无色、人们熟悉其臭味的有毒气体。存在于自然界，主要由动植物厌氧腐烂分解生成；人们在外太空也探测到了氨。一些植物(主要是豆科植物)与根瘤菌结合，“固定”大气中的氮来生成氨。

自古以来，人们就知道氨的气味。著名化学家Joseph Black(苏格兰)、Peter Woulfe(爱尔兰)、Carl Wilhelm Scheele(瑞典/德国) 和Joseph Priestley(英格兰)在18世纪分离出了氨。1785年，法国化学家Claude Louis Berthollet测定了它的元素组成。

工业上，人们通过氮气和氢气在高温高压下的催化反应来生产氨。这一工艺是1909年由德国化学家Fritz Haber和Carl Bosch开发的。两人都由于他们的出色工作而获得了诺贝尔化学奖，但获奖时间相差甚远：Haber于1918年获得诺贝尔化学奖，而Bosch则于1931年获得诺贝尔化学奖。Haber–Bosch工艺至今仍在被使用。

2020年，氨的全球产能为2.24亿吨(Mt)。实际产量为1.87亿吨，在全球化学品产量中排名第九。

大部分氨产量(约85%)被直接或间接用于农业。由氨制成的化肥包括尿素、磷酸铵、硝酸铵和其他硝酸盐。从氨生成的其他重要化学品有硝酸、肼、氰化物和氨基酸。

氨曾被广泛用作制冷剂。目前已经被氯氟烃和氢氯氟烃(它们也处于环境审查中)取代。最常见的家用氨可能存在于玻璃清洁剂中。

氨极易溶于水；它的确切溶解度取决于温度(参见信息速览)。氨水也被称为氢氧化铵，但是这个分子不能被分离出来。氨在配位化合物中作为配体时，被称为“氨络”。

尽管氨在农业上被广泛使用，然而目前的氨是由化石燃料衍生的氢制成的，因此不是一种“绿色”产品。但是，如果氢是通过其他方法制造的，比如风能或太阳能电解水，那么环保氨就有可能出现。

氨可以作为燃料在标准发动机中燃烧。催化剂公司Haldor Topsoe(Kongens Lyngby, Denmark)的一项研究得出结论：用绿色氨替代传统的船舶燃料既省钱又能消除温室气体的一个重要来源。它也有可能被用于飞机燃料。在过渡时期，氨可以与传统燃料混合使用。

氨信息速览

CAS 登记号	7664-41-7
SciFinder命名	Ammonia
分子式	H₃N
摩尔质量	17.03 g/mol
外观	无色气体
沸点	–33.3 ºC
水溶性	≈530 g/L (20 ºC) ≈320 g/L (25 ºC)

氨危害信息

GHS*分类：受压气体，液化气
H280-受压气体；加热可能会爆炸
GHS分类：皮肤腐蚀/刺激，分类1B
H314-导致严重皮肤烧伤
GHS分类：严重的眼睛损伤/眼睛刺激，分类1
H318-导致严重的眼睛损伤
GHS分类：急性毒性，吸入，分类3
H331-吸入有毒
GHS分类：对水环境有危害，急性危害，分类1
H400-对水生生物有极高毒性

【关于每周分子】

自2001年以来，“每周分子”已成为广受欢迎的栏目。多数分子由读者推荐。每个结构都经由科学家审查，并以3-D和平面图像的形式显示，同时附有该分子简介。可以通过美国化学文摘社 (CAS) 提供的SciFinder中的CAS REGISTRY获取“每周分子”的更多信息。CAS REGISTRY中的每条物质信息都展示了物质的CAS登记号、索引名、通用名、商品名、书目信息等其他更多信息。发送邮件至motw@acs.org推荐您感兴趣的分子吧。

Ammonia is a colorless, poisonous gas with a familiar noxious odor. It occurs in nature, primarily produced by anaerobic decay of plant and animal matter; and it also has been detected in outer space. Some plants, mainly legumes, in combination with rhizobia bacteria, “fix” atmospheric nitrogen to produce ammonia.

Ammonia has been known by its odor since ancient times. It was isolated in the 18th century by notable chemists Joseph Black (Scotland), Peter Woulfe (Ireland), Carl Wilhelm Scheele (Sweden/Germany), and Joseph Priestley (England). In 1785, French chemist Claude Louis Berthollet determined its elemental composition.

Ammonia is produced commercially via the catalytic reaction of nitrogen and hydrogen at high temperature and pressure. The process was developed in 1909 by German chemists Fritz Haber and Carl Bosch. Both received the Nobel Prize in Chemistry for their work, but in widely separated years: Haber in 1918 and Bosch in 1931. The fundamental Haber–Bosch process is still in use today.

In 2020, the worldwide ammonia production capacity was 224 million tonnes (Mt). Actual production was 187 Mt. It ranks ninth among chemicals produced globally.

Most ammonia production—≈85%—is used directly or indirectly in agriculture. Chemical fertilizers made from ammonia include urea, ammonium phosphate, ammonium nitrate, and other nitrates. Other important chemicals produced from ammonia include nitric acid, hydrazine, cyanides, and amino acids.

Ammonia was once used widely as a refrigerant. It has largely been displaced by chlorofluorocarbons and hydrochlorofluorocarbons, which are also under environmental scrutiny. Probably the most familiar household use of ammonia is in glass cleaners.

Ammonia is highly soluble in water; its exact solubility depends on temperature (see fast facts). Aqueous ammonia is also called ammonium hydroxide, but that molecule cannot be isolated. When ammonia is used as a ligand in coordination complexes, it is called “ammine”.

Currently ammonia is made from fossil fuel–derived hydrogen and is therefore not a “green” product, despite its widespread use in agriculture. But environmentally green ammonia may be on the horizon if the hydrogen is made by other means, such as wind- or solar-powered electrolysis of water.

Ammonia can be burned as a fuel in standard engines. A study by the catalyst company Haldor Topsoe (Kongens Lyngby, Denmark) concluded that replacing conventional ship fuels with green ammonia would be cost-efficient and would eliminate a significant source of greenhouse gases. It potentially can be used in aircraft fuels as well. During a transition period, ammonia could be mixed with conventional fuels.

Ammoniafast facts

CAS Reg. No.	7664-41-7
SciFinder nomenclature	Ammonia
Empirical formula	H₃N
Molar mass	17.03 g/mol
Appearance	Colorless gas
Boiling point	-33 ºC
Water solubility	≈530 g/L (20 ºC) ≈320 g/L (25 ºC)

Ammonia hazard information

Hazard class: Gases under pressure, liquefied gas
H280-Contains gas under pressure; may explode if heated
Hazard class: Skin corrosion/irritation, category 1B
H314-Causes severe skin irritation
Hazard class: Serious eye damage/eye irritation, category 1
H318-Causes serious eye damage
Hazard class: Acute toxicity, inhalation, category 3
H331-Toxic if inhaled
Hazard class: Hazardous to the aquatic environment, acute hazard, category 1
H400-Very toxic to aquatic life

About Molecule of the Week

MOTW has been a popular feature on ACS website since 2001. Many molecules are suggested by our website visitors. Every structure is reviewed by a scientist and displayed in 3-D and flat images with a brief description. Each week’s molecule also links to a sample record from the CAS REGISTRY, which is searched using SciFinder. Each record displays the registry number, index name and synonyms, bibliographic information, and more. Send us a molecule suggestion at motw@acs.org.

往期精选：

每周分子Molecule of the Week：氯化十六烷基吡啶

每周分子Molecule of the Week：槟榔碱

每周分子Molecule of the Week：1,6-萘吡啶

每周分子Molecule of the Week：尿素

每周分子Molecule of the Week：双环辛四烯合铀

每周分子Molecule of the Week：苯甲酸

每周分子Molecule of the Week：角鲨烯

每周分子Molecule of the Week：1H-1,2,3-三唑

每周分子Molecule of the Week：尿酸

每周分子Molecule of the Week：2-乙酰基呋喃、2-乙酰基吡咯

每周分子Molecule of the Week：硼烷-四氢呋喃