Phenyl isothiocyanate
[CAS# 103-72-0]

Identification

• Classification: Chemical reagent >> Organic reagent >> Cyanate ester / isocyanate
• Name: Phenyl isothiocyanate
• Synonyms: isothiocyanatobenzene
• Molecular Formula: C₇H₅NS
• Molecular Weight: 135.19
• CAS Registry Number: 103-72-0
• EC Number: 203-138-1
• SMILES: C1=CC=C(C=C1)N=C=S

Properties

• Density: 1.1288
• Melting point: -21 °C
• Boiling point: 221 °C
• Refractive index: 1.649-1.651
• Flash point: 87 °C

Safety Data

• Hazard Symbols: GHS05;GHS06;GHS07;GHS08;GHS09 Danger
• Risk Statements: H301-H314-H317-H318-H334-H341-H361-H400-H410
• Safety Statements: P203-P233-P260-P261-P264-P264+P265-P270-P271-P272-P273-P280-P284-P301+P316-P301+P330+P331-P302+P352-P302+P361+P354-P304+P340-P305+P354+P338-P316-P317-P318-P321-P330-P333+P317-P342+P316-P362+P364-P363-P391-P403-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Acute toxicity	Acute Tox.	3	H301
Skin corrosion	Skin Corr.	1B	H314
Skin sensitization	Skin Sens.	1	H317
Respiratory sensitization	Resp. Sens.	1	H334
Serious eye damage	Eye Dam.	1	H318
Reproductive toxicity	Repr.	2	H361
Germ cell mutagenicity	Muta.	2	H341
Chronic hazardous to the aquatic environment	Aquatic Chronic	1	H410
Acute hazardous to the aquatic environment	Aquatic Acute	1	H400
Acute toxicity	Acute Tox.	3	H331
Acute toxicity	Acute Tox.	3	H311
Acute toxicity	Acute Tox.	2	H330
Flammable liquids	Flam. Liq.	2	H225
Specific target organ toxicity - single exposure	STOT SE	3	H335

• Transport Information: UN 1693

Discovery and Applications

Phenyl isothiocyanate (PITC) is a widely used organic compound with the chemical formula C7H5NS. The compound belongs to the isothiocyanate family, which is characterized by the functional group -N=C=S. The discovery of isothiocyanates dates back to the 19th century, when PITC was first synthesized by reacting aniline (aniline) with carbon disulfide and subsequently treating it with lead nitrate.

Phenyl isothiocyanate is a colorless to pale yellow liquid with a pungent odor. It has a boiling point of 221°C and is relatively stable under standard conditions. The synthesis of PITC can be achieved by a variety of methods, the most common being the reaction of aniline with thiophosgene or chlorination using phenylthiourea.

The most important application of phenyl isothiocyanate is in the field of peptide sequencing, particularly in Edman degradation. This technique, developed by Pehr Edman in the mid-20th century, uses PITC to label the N-terminal amino acid of a peptide. The labeled amino acid can then be cleaved and identified, allowing the amino acid sequence to be determined sequentially. This application has played a key role in advancing protein structure and function research.

Phenyl isothiocyanate is also used in organic synthesis as a reagent for the introduction of phenylthiocarbamoyl groups. It reacts with primary and secondary amines to form thioureas, which are useful as intermediates in the synthesis of pharmaceuticals, agrochemicals, and other organic compounds. The versatility of PITC in forming a wide range of derivatives makes it valuable for the design of complex molecules in medicinal chemistry.

In addition to its role in chemical synthesis and analysis, phenyl isothiocyanate exhibits biological activities, including antibacterial, antifungal, and anticancer properties. These activities are attributed to its ability to modify proteins and disrupt cellular processes. Studies have shown that PITC can inhibit the growth of certain cancer cells, making it a compound of interest for the development of new therapeutic agents.

While phenyl isothiocyanate can be used in a variety of applications, it must be handled with care. It can irritate the skin, eyes, and respiratory system. Appropriate protective equipment, such as gloves and goggles, should be used when working with this compound. In case of contact, the affected area should be rinsed thoroughly with water and medical attention sought if necessary.

References

1993. Analysis of the neurotoxin beta-ODAP and its alpha-isomer by precolumn derivatization with phenylisothiocyanate. Analytical Biochemistry, 208(2).
DOI: 10.1006/abio.1993.1038

2001. Amino Acid Measurement in Body Fluids Using PITC Derivatives. Methods in Molecular Biology, 159.
DOI: 10.1385/1-59259-047-0:169

2005. Photodissociation tandem mass spectrometry at 266 nm of an aliphatic peptide derivatized with phenyl isothiocyanate and 4‐sulfophenyl isothiocyanate. Rapid Communications in Mass Spectrometry, 19(10).
DOI: 10.1002/rcm.1922