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：2-糠硫醇

Molecule of the Week: 2-Furfurylthiol

2-糠硫醇，也被称为2-呋喃甲硫醇、糠硫醇和其他许多名称，是一种有机油性液体，是烘焙和冲泡咖啡的主要气味成分。

20世纪20年代末，在德国弗莱堡大学著名的有机化学家Hermann Staudinger申请的一系列专利中，重点披露了2-糠硫醇的合成。在1928年的一项加拿大专利中，Staudinger和共同发明人Thadeus Reichstein用硫化氢铵(NH₄HS)处理糠醛，制得双-(呋喃甲基)二硫化物，然后将其还原成硫醇。在同年的一项瑞士专利中，这些发明人利用硫化钠、元素锌、铝和钠作为有效的还原剂。

1955年发表在《有机合成》(Organic Synthese)杂志上的一篇文章中，Danish Pharmaceutical College(丹麦哥本哈根)的Helmer Kofod报道了一种合成2-糠硫醇的方法：通过糠醇和硫脲的酸催化反应生成异硫脲中间体，该中间体在碱水解时释放出游离硫醇。

墨西哥新莱昂大学 (University of Nuevo León, 墨西哥蒙特雷)的José Giral和Aureliano García Fernández很可能是在1944年首次发现了2-糠硫醇具有咖啡香味。六年后，Staudinger和Reichstein，以及Staudinger的儿子Hansjürgen共同发表了一篇关于将硫醇用作咖啡调味剂的专利的综述。

联合国粮食及农业组织这样描述2-糠硫醇：“无色油状液体；扩散性很强的臭味，稀释后变得宜人，带有咖啡味、焦糖烧焦味和甜味”。换句话说，在危害信息表中描述的这种表面上令人讨厌的化合物，如果少量地吸入，则会变得好闻。

2-糠硫醇信息速览

CAS 登记号	98-02-2
SciFinder命名	2-Furanmethanethiol
分子式	C₅H₆OS
摩尔质量	114.17 g/mol
外观	无色油状液体
沸点	155 °C
水溶性	0.5 g/L

2-糠硫醇危害信息

GHS*分类：易燃液体，分类3
H226-易燃液体和蒸汽
GHS分类：急性毒性，口服，分类4
H302-吞食有害
GHS分类：严重眼损伤/眼刺激，分类2A
H319-会引起严重的眼刺激
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，单次接触，呼吸道刺激，分类3
H335-可能引起呼吸道刺激
GHS分类：急性毒性，皮肤，分类4
H312-皮肤接触有害

【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CAS SciFinderⁿ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。

2-Furfurylthiol, which also goes by 2-furanmethanethiol, furfuryl mercaptan, and many other names, is an oily organic liquid that is best known as the principal odor component of roasting and brewing coffee.

In the late 1920s, a series of patents, primarily by noted organic chemist Hermann Staudinger at the University of Freiburg (Germany), described syntheses of 2-furfurylthiol. In a 1928 Canadian patent, Staudinger and co-inventor Thadeus Reichstein treated furfural with ammonium hydrogen sulfide (NH₄HS) to make bis(furylmethyl) disulfide, which they then then reduced to the thiol. In a Swiss patent the same year, these inventors cited sodium sulfide and elemental zinc, aluminum, and sodium as useful reducing agents.

In a 1955 article in Organic Syntheses, Helmer Kofod at the Danish Pharmaceutical College (Copenhagen) described a synthesis of 2-furfurylthiol via the acid-catalyzed reaction of furfuryl alcohol and thiourea to produce an isothiouronium intermediate, which liberates the free thiol upon base hydrolysis.

In 1944, José Giral and Aureliano García Fernández at the University of Nuevo León (Monterrey, Mexico) were likely the first to identify 2-furfurylthiol with coffee aroma. Six years later, Staudinger and Reichstein, along with Staudinger’s son Hansjürgen, published a review of patents that covered the use of the thiol as a coffee-flavoring agent.

The Food and Agriculture Organization of the United Nations describes 2-furfurylthiol thus: “colourless oily liquid; extremely powerful and diffusive odour which on dilution becomes agreeable, coffee-like, caramellic-burnt, sweet”. In other words, the seemingly nasty compound described in the hazard information table becomes appealing when sniffed in small quantities.

2-Furfurylthiolfast facts

CAS Reg. No.	98-02-2
SciFinder nomenclature	2-Furanmethanethiol
Empirical formula	C₅H₆OS
Molar mass	114.17 g/mol
Appearance	Colorless oily liquid
Boiling point	155 °C
Water solubility	0.5 g/L

2-Furfurylthiol hazard information

Flammable liquids, category 3
H226-lammable liquid and vapor
Acute toxicity, oral, category 4
H302-Harmful if swallowed
Acute toxicity, dermal, category 4
H312-Harmful in contact with skin
Serious eye damage/eye irritation, category 2A
H319-Causes serious eye irritation
Acute toxicity, inhalation, category 3
H335-Toxic if inhaled
Specific target organ toxicity, single exposure, respiratory tract irritation, category 3
H335-May cause respiratory irritation

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 CAS SciFinderⁿ. 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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