What molecule am I?
Hippuric acid, or N-benzoylglycine, is an amino acid derivative found in the urine of herbivorous animals. The name is derived from Greek hippos (horse) and ouron (urine). In 1829, the pioneering German chemist Justus von Liebig so named it because his research on the compound concentrated on horse urine.
Hippuric acid also occurs in avocadoes (Persea americana) and common beans (Phaseolus vulgaris). As its chemical name suggests, the compound is formed by the reaction of benzoic acid and glycine in the urine.
Later in the 19th century, von Liebig鈥檚 last student, Oscar Loew, also studied hippuric acid. In 1879, Loew wrote about the source of the acid in herbivores鈥� urine. According to an account of the article in the first volume of the Journal of the American Chemical 中国365bet中文官网 (1879), quinic acid1 in hay during digestion. This finding had in 1863 by Eduard Lautemann, a student of another important German chemist, Hermann Kolbe.
Synthetic hippuric acid is produced similarly to the biochemical reaction: Glycine is acylated with benzoyl chloride in the presence of base, followed by acidification to form the acid. Hydrolysis in strong base restores it to glycine and benzoic acid.
Extensive information about the biochemistry of hippuric acid and its implications for human health can be found in the on the compound.
1. CAS Reg. No. 77-95-2.
Hippuric acid聽hazard information*
| Hazard class** | GHS code and hazard statement | |
|---|---|---|
| Acute toxicity, oral, category 4 | H302鈥擧armful if swallowed |  |
| Skin corrosion/irritation, category 2 | H315鈥擟auses skin irritation | |
| Serious eye damage/eye irritation, category 1 | H318鈥擟auses serious eye damage |  |
| Specific target organ toxicity, single exposure, respiratory tract irritation, category 3 | H335鈥擬ay cause respiratory irritation | |
*Compilation of multiple safety data sheets.聽Some sources report 鈥渘ot a hazardous substance or mixture鈥�.
**Globally Harmonized System (GHS) of Classification and Labeling of Chemicals.聽.
Molecules from the journals
(鈥�)-Illisimonin A1 is a caged sesquiterpenoid found in the fruit of Illicium simonsii, a flowering plant that grows in southern China. It was by Jing Qu, Shi-Shan Yu, and colleagues at the Chinese Academy of Medical Sciences/Peking Union Medical College (Beijing), who also reported its structure and absolute configuration and described its neuroprotective effects against oxygen-glucose deprivation鈥搃nduced SH-SY5Y cell injury.
Two years later, Alexander S. Burns and Scott D. Rychnovsky* at the University of California, Irvine, reported a revised structure of (鈥�)-illisimonin A and the . They also confirmed its neuroprotective activity. Then, this past March, Markus Kalesse and co-workers at Leibniz University Hannover (Germany) described the , which included a Ti(III)-mediated cyclization and a semipinacol rearrangement as the key steps.
A catenane is a molecule in which two individual ring compounds are intertwined. In 1960, Edel Wasserman at the Bell Telephone Laboratories (Murray Hill, NJ, now Nokia Bell Labs) reported the , which consisted of a cyclotetratriacontane ring that contained five deuterium atoms2 interlocked with the acyloin 2-hydroxycyclotetratriacontanone3. The assemblage soon became known as Wasserman's catenane4.
Wasserman鈥檚 method is known as the 鈥渟tatistical approach鈥� to catenanes, in which the ring closure of one molecule (in this case, the acyloin) within the other (the hydrocarbon) is essentially random, resulting in a small yield of the catenane. The analytical methods available to Wasserman could not affirm the existence of a catenane, so Wasserman was obliged to use indirect chemical methods to determine the structure. Consequently, Wasserman鈥檚 claim of synthesizing a catenane was under suspicion for more than 60 years.
In April, David A. Leigh and collaborators at the University of Manchester (UK) and East China Normal University (Shanghai) reported the results of their effort to verify the structure of Wasserman's catenane. They used modern tools such as tandem mass spectrometry, deuterium NMR spectroscopy, and fluorescent tag labeling to prove that , thus confirming Wasserman鈥檚 claim.
For additional information about Wasserman's catenane, see recent articles by and .
1. CAS Reg. No. 2162197-76-2.
2. CAS Reg. No. 119212-00-9.
3. CAS Reg. No. 119211-99-3.
4. CAS Reg. No. 119212-01-0.
Molecules from the Journals
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Hippuric acid fast facts
| CAS Reg. No. | 495-69-2 |
| SciFinder nomenclature | Glycine, N-benzoyl- |
| Empirical formula | C9H9NO3 |
| Molar mass | 179.17 g/mol |
| Appearance | White crystals or powder |
| Melting point | 191 掳C |
| Water solubility | 鈮�4 g/L |
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