3-Iodobenzyl bromide
[CAS# 49617-83-6]

Identification

• Classification: Organic raw materials >> Hydrocarbon compounds and their derivatives >> Hydrocarbon halide
• Name: 3-Iodobenzyl bromide
• Synonyms: 1-(bromomethyl)-3-iodobenzene
• Molecular Formula: C₇H₆BrI
• Molecular Weight: 296.93
• CAS Registry Number: 49617-83-6
• EC Number: 628-893-8
• SMILES: C1=CC(=CC(=C1)I)CBr

Properties

• Density: 2.1±0.1 g/cm³ Calc.^*
• Melting point: 46 - 51 ºC (Expl.)
• Boiling point: 281.2±23.0 ºC 760 mmHg (Calc.)^*, 338.5 ºC (Expl.)
• Flash point: 123.9±22.6 ºC (Calc.)^*, 113 ºC (Expl.)
• Index of refraction: 1.656 (Calc.)^*

^* Calculated using Advanced Chemistry Development (ACD/Labs) Software.

Safety Data

• Hazard Symbols: GHS05 Danger
• Hazard Statements: H314-H318
• Precautionary Statements: P260-P264-P264+P265-P280-P301+P330+P331-P302+P361+P354-P304+P340-P305+P354+P338-P316-P317-P321-P363-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Skin corrosion	Skin Corr.	1B	H314
Serious eye damage	Eye Dam.	1	H318
Specific target organ toxicity - single exposure	STOT SE	3	H335
Eye irritation	Eye Irrit.	2	H319
Substances or mixtures corrosive to metals	Met. Corr.	1	H290
Acute toxicity	Acute Tox.	4	H332
Acute toxicity	Acute Tox.	4	H302
Skin corrosion	Skin Corr.	1C	H314

• Transport Information: UN 3261

Discovory and Applicatios

3-Iodobenzyl bromide is an organic compound belonging to the class of halogenated aromatic compounds. It is characterized by the presence of both an iodine atom and a bromine atom attached to a benzyl group, with the iodine located at the meta position of the aromatic ring. This compound is widely used in organic synthesis due to its reactivity and versatility in various chemical reactions.

The discovery and development of 3-iodobenzyl bromide can be traced back to the broader study of halogenated benzyl compounds, which have been utilized for decades in the synthesis of a wide variety of organic molecules. The iodine atom in 3-iodobenzyl bromide serves as an excellent leaving group, which makes this compound particularly useful in nucleophilic substitution reactions. The bromine atom, on the other hand, enhances the reactivity of the benzyl group, enabling the compound to serve as an effective electrophile in several synthetic pathways.

The typical synthesis of 3-iodobenzyl bromide involves the introduction of iodine at the meta position of toluene or another suitable starting material using iodine or iodine reagents in the presence of an oxidizing agent. Bromination of the resulting iodobenzyl intermediate is then achieved using a brominating agent, such as N-bromosuccinimide (NBS), under conditions that favor selective substitution at the benzylic position. The reaction yields 3-iodobenzyl bromide in good yields and high purity.

One of the primary applications of 3-iodobenzyl bromide is in the synthesis of complex organic molecules, including those used in pharmaceuticals, agrochemicals, and materials science. Due to the presence of two halogen atoms, the compound is an ideal building block for creating functionalized aromatic compounds via a range of chemical transformations. For example, it is commonly used in Suzuki coupling reactions to form biaryl compounds, a class of molecules that are prevalent in drug discovery, particularly for targeting G-protein coupled receptors (GPCRs) and other biological targets.

Additionally, 3-iodobenzyl bromide is often employed as a reagent in the formation of various carbon-carbon bonds through nucleophilic aromatic substitution reactions. The iodobenzyl group is reactive toward a variety of nucleophiles, including amines, alcohols, thiols, and other functional groups, allowing for the introduction of diverse functionalities into a target molecule. This reactivity is exploited in the synthesis of compounds with complex architectures, such as pharmaceuticals and fine chemicals, where precise functional group positioning is crucial.

The compound's utility is not limited to synthetic organic chemistry; it has also been explored in the field of materials science, particularly in the preparation of functionalized polymers and novel materials. By incorporating 3-iodobenzyl bromide into polymer backbones, it is possible to create light-sensitive materials or materials with controlled degradation properties, which have applications in drug delivery systems and smart materials. These materials can undergo transformations upon exposure to specific wavelengths of light, making them valuable for developing systems that require spatial and temporal control.

In addition to its synthetic utility, 3-iodobenzyl bromide has also been investigated in the development of imaging agents for use in diagnostic applications. The incorporation of the iodine atom into molecular probes can enhance their visibility in imaging techniques such as positron emission tomography (PET) or single-photon emission computed tomography (SPECT), where the iodine isotope provides a detectable signal. These developments have the potential to improve diagnostic accuracy, particularly in the detection of cancers and other diseases.

The physical properties of 3-iodobenzyl bromide include its appearance as a pale yellow solid that is soluble in common organic solvents like dichloromethane, acetone, and ethyl acetate. The compound is stable under normal conditions but should be stored away from moisture and strong bases to avoid unwanted degradation or reaction. It is also sensitive to light, which can catalyze its decomposition under certain conditions.

Safety precautions are essential when working with 3-iodobenzyl bromide, as both iodine and bromine are hazardous materials. Proper handling in a fume hood is recommended to avoid inhalation of vapors, and gloves, goggles, and lab coats should be worn to minimize direct contact. It is also important to note that the compound may cause skin and eye irritation, and care should be taken to avoid accidental exposure.

In conclusion, 3-iodobenzyl bromide is a versatile and valuable reagent in organic synthesis, with applications spanning pharmaceuticals, materials science, and imaging. Its reactivity in nucleophilic substitution reactions and coupling reactions makes it an important building block for creating complex molecules, while its role in the development of light-sensitive and diagnostic materials further enhances its significance in modern chemistry.

References

2005. Multi-residue method for the determination of thyreostats in urine samples using liquid chromatography coupled to tandem mass spectrometry after derivatisation with 3-iodobenzylbromide. Journal of Chromatography A, 1082(2).
DOI: 10.1016/j.chroma.2005.06.055

2015. Synthesis, crystal structures and magnetic properties of three complexes containing bis(maleonitriledithiolate) copper(II) anion and meta-substituted benzyl isoquinolinium cations. Transition Metal Chemistry, 41(2).
DOI: 10.1007/s11243-015-0016-1

2007. Of Benzyl Halides. Science of Synthesis.
URL: https://science-of-synthesis.thieme.com/app/text/?id=SD-020-00108