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：胍

Molecule of the Week: Guanidine

胍是在自然界中的植物(例如稻壳和萝卜汁)和动物(例如贻贝和蚯蚓)中被发现的一种富含氮的小有机化合物。与它的氧类似物碳酸不同，胍存在于环境条件下(即不在溶液中，也不在低温下)。胍不应与鸟嘌呤混淆，鸟嘌呤是一种嘌呤衍生物，存在于蝙蝠和鸟的粪便中。

许多文献资料表明鸟嘌呤在水中非常易溶。但是，如信息速览表中所示，胍只是微溶的。然而，它非常吸湿。它的盐酸盐是高度水溶性的，为一种常见商品。如危害信息表所示，游离碱具有剧毒。

人们于19世纪后期在自然界中发现了胍。1907年，意大利化学家Celso Ulpiani获得了德国专利，该专利披露了用双氰胺与强酸反应生成硝酸胍(实际上是胍盐)。24年后，布鲁克林理工学院(现为纽约大学坦登工程学院)的G.B.L. Smith、V. J. Sabetta和O. F. Steinbach, Jr.发表了一项综合研究，该研究揭示了将双氰胺(aka 2-cyanoguanidine)转化为硝酸胍然后再转化为硝基胍(一种威力巨大的的爆炸物)。

胍硫氰酸盐与当前的COVID-19大流行有着特别的联系。今年6月，美国食品药品监督管理局(FDA)警告实验室不要使用含有硫氰酸盐或其他胍基化学品的介质来运输COVID-19样品。因为：胍化合物可分解为剧毒的氰化氢(HCN)气体。FDA还建议，当工作人员不知道运输介质的成分时，应当将其视为含有胍产品一样进行处理。截至FDA警告之日，尚未有向该机构报告与HCN有关的伤害。

胍信息速览

CAS登记号	113-00-8
SciFinder命名	Guanidine
分子式	CH₅N₃
摩尔质量	59.07 g/mol
外观	吸湿性白色晶体
沸点	50 ºC
水溶性	1.84 g/L

胍危害信息

GHS*分类：易燃液体，分类2
H225-高度易燃液体和蒸汽
GHS分类：急性毒性，口服，分类3
H301-吞食有毒
GHS分类：急性毒性，皮肤，分类3
H311-与皮肤接触有毒
GHS分类：皮肤腐蚀/刺激，分类1
H314-引起严重的皮肤烧伤
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：特定靶器官毒性，单次暴露，分类1
H370-导致器官损伤

【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。

Guanidine is a small, nitrogen-rich organic compound found in nature in plants (e.g., rice hulls and turnip juice) and animals (e.g., mussels and earthworms). Unlike its oxygen analogue, carbonic acid, it exists at ambient conditions (i.e., not in solution nor at cryogenic temperatures). Guanidine should not be confused with guanine, a purine derivative that is found in bat and bird feces.

Many literature sources state that guanine is very soluble in water; but, as shown in the fast facts table, it is only slightly soluble. It is, however, very hygroscopic. Its hydrochloride salt is highly water-soluble and is the usual article of commerce. The free base is extremely toxic, as shown in the hazard information table.

Guanidine was discovered in nature in the late 19th century. In 1907, a German patent was awarded to Italian chemist Celso Ulpiani for the reaction of dicyanamide with strong acid to produce guanidine (actually, guanidinium) nitrate. Twenty-four years later, G.B.L. Smith, V. J. Sabetta, and O. F. Steinbach, Jr., at the Polytechnic Institute of Brooklyn (now New York University Tandon School of Engineering) published a comprehensive study of the conversion of dicyandiamide (aka 2-cyanoguanidine) to guanidinium nitrate and then to nitroguanidine, a powerful explosive.

Guanidine’s hydrothiocyanate salt has an interesting connection to the current COVID-19 pandemic. This past June, the US Food and Drug Administration warned laboratories not to use media that contain the thiocyanate salt or other guanidine-based chemicals to transport COVID-19 samples. The reason: Guanidine compounds can decompose to highly toxic hydrogen cyanide (HCN) gas. The FDA also advised that when personnel do not know the ingredients of a transport medium, they should handle it as though it contained a guanidine product. As of the date of FDA’s warning, no HCN-related injuries had been reported to the agency.

Guanidine fast facts

CAS Reg. No.	113-00-8
SciFinder nomenclature	Guanidine
Empirical formula	CH₅N₃
Molar mass	59.07 g/mol
Appearance	Hygroscopic white crystals
Melting point	50 ºC
Water solubility	1.84 g/L

Guanidine hazard information

Hazard class: Flammable liquids, category 2
H225-Highly flammable liquid and vapor
Hazard class: Acute toxicity, oral, category 3
H301-Toxic if swallowed
Hazard class: Acute toxicity, dermal, category 3
H311-Toxic in contact with skin
Hazard class:Skin corrosion/irritation, category 1
H314-Causes severe skin burns
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: Specific target organ toxicity, single exposure, category 1
H370-Causes damage to organs

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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