1-(2-Bromophenyl)-2-thiourea: Properties, Synthesis & Applications

1-(2-Bromophenyl)-2-thiourea is a brominated aryl thiourea compound widely employed as a reactive building block in medicinal chemistry and heterocyclic synthesis.

CAS Number

53812-14-9

Molecular Formula

C₇H₇BrN₂S

Molecular Weight

231.11 g/mol

Appearance

White to off-white crystalline powder

Key Functional Groups

Thiourea (–NH–C(=S)–NH₂) and ortho-bromo substituent

SKU

B185081

Chemical Structure and Physical Properties

1-(2-Bromophenyl)-2-thiourea (CAS 53812-14-9) belongs to the class of N-aryl thioureas, characterized by a thiourea functional group (–NH–C(=S)–NH₂) attached to a 2-bromophenyl ring. The ortho-bromo substituent imparts both steric and electronic effects that distinguish this compound from its para- and meta-isomers, making it particularly reactive in intramolecular cyclization and metal-catalyzed cross-coupling reactions.

The compound typically presents as a white to off-white crystalline solid with a molecular weight of 231.11 g/mol (molecular formula C₇H₇BrN₂S). The thiourea moiety confers hydrogen-bond donor and acceptor capability, contributing to the compound's solid-state packing and solubility profile. It is generally soluble in polar aprotic solvents such as DMSO and DMF, and sparingly soluble in water.

Synthesis and Preparation

The most common synthetic route to 1-(2-Bromophenyl)-2-thiourea involves the reaction of 2-bromoaniline with ammonium thiocyanate or, alternatively, with thiocarbamoyl chloride under mild aqueous or alcoholic conditions. The reaction of 2-bromoaniline with ammonium thiocyanate proceeds via initial formation of an aryl ammonium thiocyanate salt, which upon heating undergoes a Mumm rearrangement to afford the desired aryl thiourea product in good yields.

An alternative approach employs isothiocyanate chemistry: treatment of 2-bromoaniline with ammonium thiocyanate in hydrochloric acid generates an in situ aryl isothiocyanate intermediate, which is subsequently trapped by ammonia to furnish the thiourea. Purification is typically achieved by recrystallization from ethanol or ethanol–water mixtures, yielding analytically pure material suitable for downstream synthetic applications.

Research Applications in Medicinal and Heterocyclic Chemistry

1-(2-Bromophenyl)-2-thiourea serves as a versatile precursor in the synthesis of biologically active heterocyclic scaffolds. The combination of a nucleophilic thiourea group and an electrophilic C–Br bond in the ortho position enables efficient intramolecular cyclization to form benzothiazol-2-amine and related benzothiazine derivatives under oxidative or base-promoted conditions. Such scaffolds are of considerable interest in drug discovery due to their reported antimicrobial, anti-inflammatory, and anticancer properties.

Beyond cyclization, the aryl bromide handle supports palladium-catalyzed cross-coupling reactions (Suzuki, Buchwald–Hartwig, and carbonylation), allowing rapid diversification of the thiourea core into complex molecular architectures. The compound is also used in coordination chemistry as a bidentate or bridging ligand toward transition metals, generating metal–thiourea complexes with potential catalytic or biological activity.

In agrochemical research, N-aryl thioureas bearing halogen substituents have been investigated as lead structures for fungicidal and herbicidal agents, further broadening the utility of this compound class.

Handling, Storage, and Safety Considerations

As with all organobromine and thiourea-containing compounds, 1-(2-Bromophenyl)-2-thiourea should be handled with appropriate personal protective equipment (PPE), including nitrile gloves, safety glasses, and a laboratory coat. Operations generating dust or aerosols should be conducted in a fume hood.

The compound should be stored in a tightly sealed container in a cool, dry, well-ventilated location, away from strong oxidizing agents, strong acids, and sources of ignition. Recommended storage temperature is typically 2–8 °C or room temperature as specified on the product label. Consult the Safety Data Sheet (SDS) provided by Aladdin Scientific for detailed hazard classifications, first-aid measures, and disposal requirements prior to use.

Thiourea derivatives in general may exhibit mild toxicity; avoid inhalation of dust and contact with skin or eyes. Dispose of waste material in accordance with local environmental regulations.

Frequently asked questions

What is 1-(2-Bromophenyl)-2-thiourea used for in research?

It is primarily used as a building block in the synthesis of benzothiazole and benzothiazine heterocycles with potential antimicrobial and anticancer activity. The ortho-bromo group also enables palladium-catalyzed cross-coupling reactions to diversify molecular structures.

How should 1-(2-Bromophenyl)-2-thiourea be stored?

Store in a tightly sealed container in a cool, dry, and well-ventilated area, away from oxidizers and ignition sources. Refer to the Aladdin Scientific product label and SDS for the specific recommended temperature range.

What solvents are suitable for dissolving 1-(2-Bromophenyl)-2-thiourea?

The compound is generally soluble in polar aprotic solvents such as DMSO and DMF. It shows limited solubility in water and common non-polar organic solvents. Preliminary solubility testing is recommended before use in biological assays.

How does the ortho-bromo substituent influence reactivity compared to other isomers?

The ortho-bromo group is geometrically positioned to facilitate intramolecular reactions with the adjacent thiourea nitrogen or sulfur, enabling efficient ring-closure to benzothiazole scaffolds. This proximity effect distinguishes the ortho-isomer from para- and meta-analogues in cyclization chemistry.

References

1. March, J. Advanced Organic Chemistry: Reactions, Mechanisms, and Structure, 4th ed.; Wiley-Interscience: New York, 1992. (General thiourea synthesis methods)
2. Kaur, H.; Kumar, S.; Singh, I. P.; Bhutani, K. K. Thiourea derivatives in drug discovery: a review of medicinal chemistry applications. (General review reference — verify specific journal and year)
3. Aladdin Scientific. Product Data Sheet: 1-(2-Bromophenyl)-2-thiourea, SKU B185081. (Consult current product page for verified physicochemical data)

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