每周分子 | Molecule of the Week

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

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每周分子：氟化氢

Molecule of the Week: Hydrogen fluoride

氟化氢(HF)是一种剧毒、腐蚀性气体和液体。作为相对分子质量最轻的卤化氢，HF的沸点高得惊人，甚至高于碘化氢。原因是氟原子的电负性大，使氢和氟原子在液相中形成氢键。其它卤化氢则通过弱得多的范德华力连接。

命名混淆？

HF分子通常称为氟化氢；但它在CAS SciFinder系列中的CAS索引名称是氢氟酸。这种用法也适用于其它卤化氢，并且有可能与其相同化合物水溶液的术语混淆。

在水溶液中，HF是一种弱酸，其pK_a为3.17，再次对比氟化氢和其它卤化氢，其它卤化氢在溶液中完全电离，但是HF的其它特性并没有什么弱项。HF作为气体、液体或在溶液中，对多种物质都具有极强的腐蚀性，包括大多数金属、玻璃和其它形式的二氧化硅以及动植物组织。

虽然HF溶液至少在HF气体被发现的100年前就已为人所知并使用了，但是法国化学家Edmond Frémy在19世纪中叶才发现了HF气体。现在HF的主要来源是矿物萤石(氟化钙)；用硫酸处理矿物萤石生成HF气体。大量的HF也可以从含有氟离子和磷酸盐的矿物磷灰石中作为磷肥生产的副产品获得。

几乎所有商业含氟化学品的合成都是从HF开始的。这些含氟化学品包括：无机物，如：分子氟 (F₂)、用于生产铝的冰晶石(Na₃AlF₆)和各种金属氟化物；以及有机物，如：聚合物(例如聚四氟乙烯或特氟龙)、氯氟烃制冷剂和全氟烷基物质 (PFAS)；它们目前都是新闻报道中臭名昭著的环境污染物。HF本身在石油精炼中用作催化剂。

HF更现代的用途是使用在化学激光器中。加州大学伯克利分校的George C. Pimentel是该领域的先驱。他开发了数十种基于化学反应的红外激光器，其中的一些红外激光器就是利用氟和氢反应生成HF。HF激光器发射2.7–2.9 µm波长范围内的红外光；如果氢被氘取代，波长则会增加到 ≈3.8 µm。

氟化氢信息速览

CAS 登记号	7664-39-3
SciFinder命名	Hydrofluoric acid
分子式	HF
摩尔质量	20.01 g/mol
外观	无色气体
沸点	19.5 ºC
水溶性	混溶

氟化氢危害信息

GHS*分类：加压气体、液化气体
H280-含有加压气体；加热会爆炸
GHS分类：急性毒性，口服，类别2
H300-吞食致命
GHS分类：急性毒性，皮肤，类别4
H300-皮肤接触致命
GHS分类：皮肤腐蚀/刺激，类别1A
H314-引起严重的皮肤灼伤和眼睛损伤
GHS分类：严重眼损伤/眼刺激，类别 1
H318-引起严重眼损伤
GHS分类：急性毒性，吸入，类别2
H332-吸入致命
GHS分类：特定目标器官毒性，单次暴露，呼吸道刺激，类别3
H335-可能引起呼吸道刺激
GHS分类：单纯窒息剂
H380-会置换氧气并导致快速窒息

【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。

Hydrogen fluoride (HF) is an extremely toxic, corrosive gas and liquid. As the lightest of the hydrogen halides, it has a surprisingly high boiling point, higher even than that of hydrogen iodide. The reason is the strong electronegativity of the fluorine atom, which causes hydrogen and fluorine atoms to form hydrogen bonds in the liquid phase. The other hydrogen halides are connected by much weaker van der Waals forces.

Nomenclature confusion？

The molecule HF is commonly called hydrogen fluoride; but its Chemical Abstracts Service name, as found in SciFinder, is hydrofluoric acid. This usage also applies to the other hydrogen halides and has the potential for confusion with the terminology for aqueous solutions of the same compounds.

In aqueous solution, HF is a weak acid, with a pK_a of 3.17, again in contrast with the other hydrogen halides, which are all completely ionized in solution. But there is nothing weak about HF’s other properties. As a gas, as a liquid, or in solution, it is extremely aggressive toward a wide range of substances, including most metals, glass and other forms of silica, and animal and plant tissue.

French chemist Edmond Frémy discovered HF gas in the mid-19th century, although HF solutions had been known and used at least 100 years earlier. Its main source today is the mineral fluorite (calcium fluoride), which is treated with sulfuric acid to form HF gas. Significant amounts of HF also are obtained as a byproduct of phosphate fertilizer manufacture from the mineral apatite, which contains fluoride ion as well as phosphate.

The synthesis of almost all commercial fluorine-containing chemicals begins with HF. These include inorganics, such as molecular fluorine (F₂), cryolite (Na₃AlF₆) for aluminum production, and a wide range of metal fluorides; and organics as diverse as polymers (e.g., polytetrafluoroethylene, or Teflon), chlorofluorocarbon refrigerants, and perfluoroalkyl substances (PFAS), which currently are in the news as notorious environmental contaminants. HF itself is used as a catalyst in petroleum refining.

A more modern use of HF is in chemical lasers. George C. Pimentel at the University of California, Berkeley, a pioneer in the field, developed dozens of infrared lasers based on chemical reactions, including some that use the reaction of fluorine and hydrogen to form HF. HF lasers emit IR light in the 2.7–2.9 µm wavelength range; if the hydrogen is replaced by deuterium, the wavelength increases to ≈3.8 µm.

Hydrogen fluoridefast facts

CAS Reg. No.	7664-39-3
SciFinder nomenclature	Hydrofluoric acid
Empirical formula	HF
Molar mass	20.01 g/mol
Appearance	Colorless gas
Boiling point	19.5 ºC
Water solubility	Miscible

Hydrogen fluoride information

Gases under pressure, liquefied gas
H280-Contains gas under pressure; may explode if heated
Acute toxicity, oral, category 2
H300-Fatal if swallowed
Acute toxicity, dermal, category 1
H310-Fatal in contact with skin
Skin corrosion/irritation, category 1A
H314-Causes severe skin burns and eye damage
Serious eye damage/eye irritation, category 1
H318-Causes serious eye damag
Acute toxicity, inhalation, category 2
H330-Fatal if inhaled
Specific target organ toxicity, single exposure, respiratory tract irritation, category 3
H335-May cause respiratory irritation
Simple asphyxiant
H380-May displace oxygen and cause rapid suffocation

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.

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