Phenylthiocarbamide
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| Names | |||
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IUPAC name
Phenylthiourea
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| Other names
N-Phenylthiourea; 1-Phenylthiourea
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| Identifiers | |||
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3D model (Jmol)
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| ChEBI | |||
| ChemSpider | |||
| ECHA InfoCard | 100.002.865 | ||
| MeSH | Phenylthiourea | ||
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PubChem CID
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| Properties | |||
| C7H8N2S | |||
| Molar mass | 152.22 g·mol−1 | ||
| Appearance | White to slightly yellow powder | ||
| Density | 1.294 g/cm3 | ||
| Melting point | 145 to 150 °C (293 to 302 °F; 418 to 423 K) | ||
| Soluble in boiling water | |||
| Hazards | |||
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EU classification (DSD)
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 T+ |
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| NFPA 704 | |||
| Lethal dose or concentration (LD, LC): | |||
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LD50 (median dose)
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3 mg/kg (oral, rat) | ||
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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 (what is   ?) |
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| Infobox references | |||
Phenylthiocarbamide (PTC), also known as phenylthiourea (PTU), is an organosulfur thiourea containing a phenyl ring.
It has the unusual property that it either tastes very bitter or is virtually tasteless, depending on the genetic makeup of the taster. The ability to taste PTC is often treated as a dominant genetic trait, although inheritance and expression of this trait are somewhat more complex.
PTC also inhibits melanogenesis and is used to grow transparent fish.
About 70% of people can taste PTC, varying from a low of 58% for indigenous peoples of Australia and New Guinea to 98% for indigenous peoples of the Americas. One study has found that non-smokers and those not habituated to coffee or tea have a statistically higher percentage of tasting PTC than the general population. PTC does not occur in food, but related chemicals do, and food choice is related to a person's ability to taste PTC.
The genetic taste phenomenon of PTC was discovered in 1931 when a DuPont chemist named Arthur Fox accidentally released a cloud of a fine crystalline PTC. A nearby colleague complained about the bitter taste, while Fox, who was closer and should have received a strong dose, tasted nothing. Fox then continued to test the taste buds of assorted family and friends, setting the groundwork for future genetic studies. The genetic penetrance was so strong that it was used in paternity tests before the advent of DNA matching.
The PTC taste test has been widely used in school and college practical teaching as an example of Mendelian polymorphism in human populations. Based on a taste test, usually of a piece of paper soaked in PTC (or the less toxic PROP), students are divided into taster and non-taster groups. By assuming that PTC tasting is determined by a dominant allele at a single autosomal gene, and that the class is an unbiased sample from a population in Hardy-Weinberg equilibrium, students then estimate allele and genotype frequencies within the broader population. While this interpretation is broadly consistent with numerous studies on this trait, it is worth noting that other genes, sex, age and environmental factors all influence sensitivity to PTC. Also, there are several alleles segregating at the major gene determining the taste of PTC, particularly in African populations, and the common "taster" allele is incompletely dominant (homozygotes for this allele are more sensitive to PTC than are heterozygotes). Additionally, PTC is toxic and sensitivity to the substitute, PROP, does not show a strong association with the gene controlling ability to taste PTC.
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Wikipedia