每周分子 | Molecule of the Week

Original ACS美国化学会 ACS美国化学会 2022-07-01

每周分子: ‍环氧乙烷

Molecule of the Week: Ethylene oxide

环氧乙烷是环氧烷家族中最小的分子。它是一种有多种用途的甜味、无色气体。但是它的高反应活性会带来很多危害。

早在1859年，A. Wurtz用氢氧化钾处理乙烯氯醇制备环氧乙烷和氯化钾。 1914年，巴斯夫建立了第一家环氧乙烷工厂，该工厂使用氯醇法，但用氢氧化钙代替KOH。最终，直接氧化乙烯制备环氧乙烷取代了该方法，且直接氧化乙烯制备环氧乙烷也是当今唯一使用的方法。

环氧乙烷的用途很多。到目前为止，其主要用途是作为工业生产乙二醇及其低聚物、乙二醇醚和乙醇胺的原料。其次（但很重要），直接应用包括用于食品和纺织品的熏蒸剂；农业杀菌剂和杀虫剂；及医疗设备消毒剂。

如危害信息表所示，环氧乙烷的许多用途也使其极为危险。它的致癌性值得特别关注。美国环境保护署正根据法院命令，在2020年3月13日之前决定是否要加强2006年制定的针对环氧乙烷和其他有机化学物质造成的空气污染的标准。

在环境和工业拥护者者之间，关于空气中环氧乙烷的安全浓度存在广泛分歧。提案的范围从0.1 ppt到4 ppb（约40,000）。双方都开始向EPA施加压力，要求他们按照自己的方式来看待环氧乙烷。

环氧乙烷信息速览

CAS 登记号	75-21-8
分子式	C₂H₄O
摩尔质量	44.05 g/mol
外观	无色气体
沸点	10.4–11.0 ºC
水溶性	可溶

环氧乙烷危害信息

GHS 分类**: 易燃气体，分类1
H220—极易燃气体
GHS 分类: 压力气体，液化气
H280—包含压力气体；加热可能爆炸
GHS 分类: 皮肤腐蚀/刺激，分类2
H315—引起皮肤刺激
GHS 分类: 眼睛损伤/眼睛刺激，分类2A
H319—引起严重的眼睛刺激
GHS 分类: 急性毒性，吸入，分类3
H331—吸入有毒
GHS 分类: 特定目标器官毒性，单次接触，呼吸道刺激，分类3
H335—可能引起呼吸道刺激
GHS 分类: 生殖细胞致突变性，分类1B
H340—可能导致遗传缺陷
GHS 分类: 致癌性，分类1B
H350—可能导致癌症
GHS 分类: 对水生环境有害，急性危害，分类3
H402—对水生生物有害
GHS 分类: 对水生环境有害，长期危害，分类3
H412—对水生生物有害并具有长期影响

【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。

Ethylene oxide is the smallest of the oxirane family of molecules. It is a sweet-smelling, colorless gas that has many uses; but its high reactivity presents many hazards.

Back in 1859, A. Wurtz treated ethylene chlorohydrin with potassium hydroxide to make ethylene oxide and potassium chloride. In 1914, BASF built the first ethylene oxide plant, which used the chlorohydrin method, but with calcium hydroxide instead of KOH. This process was eventually superseded by the direct oxidation of ethylene, which is used exclusively today.

The uses of ethylene oxide are numerous. By far, its primary use is as a raw material for the industrial manufacture of ethylene glycol and its oligomers, glycol ethers, and ethanolamines. Minor, but important, direct applications include a fumigant for foods and textiles; an agricultural fungicide and insecticide; and a sterilant for medical equipment.

As shown in the hazard information table, many of ethylene oxide’s uses also make it extremely dangerous. Its carcinogenicity is of special concern. The US Environmental Protection Agency is under a court order to decide by March 13, 2020, whether to tighten the 2006 standards set for air pollution by ethylene oxide and other organic chemicals.

There is broad disagreement between environmental and industrial advocates as to the safe concentration of ethylene oxide in air. Proposals range from 0.1 ppt to 4 ppb—a factor of 40,000. Both sides are beginning to pressure EPA to see things their way.

Ethylene oxide fast facts

CAS Reg. No.	75-21-8
Empirical formula	C₂H₄O
Molar mass	44.05 g/mol
Appearance	Colorless gas
Boiling point	10.4–11.0 ºC
Water solubility	Miscible

Ethylene oxide hazard information

GHS classification**: flammable gases, category 1
H220—Extremely flammable gas
GHS classification: gases under pressure, liquefied gas
H280—Contains gas under pressure; may explode if heated
GHS classification: skin corrosion/irritation, category 2
H315—Causes skin irritation
GHS classification: eye damage/eye irritation, category 2A
H319—Causes serious eye irritation
GHS classification: acute toxicity, inhalation, category 3
H331—Toxic if inhaled
GHS classification: specific target organ toxicity, single exposure, respiratory tract irritation, category 3
H335—May cause respiratory irritation
GHS classification: germ cell mutagenicity, category 1B
H340—May cause genetic defects
GHS classification: carcinogenicity, category 1B
H350—May cause cancer
GHS classification: hazardous to the aquatic environment, acute hazard, category 3
H402—Harmful to aquatic life
GHS classification: hazardous to the aquatic environment, long-term hazard, category 3
H412—Harmful to aquatic life with long-lasting effects

*Globally Harmonized System of Classification and Labeling of Chemicals. Explanation of pictograms.

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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