Benzyl Bromide 99%, also known as alpha bromotoluene, is an aromatic compound in which the benzene ring is replaced by bromomethyl. Its chemical formula is C7H7Br, CAS 100-39-0, and it belongs to the class of benzyl halide irritants. Colorless liquid with an aromatic odor. It exhibits good solubility and can easily dissolve in common organic solvents such as ethanol and ether. However, it has poor compatibility with water and is almost insoluble in water, which to some extent limits its application in water-based systems. Due to its strong tear gas effect and uncomfortable irritating odor, it was used as a chemical weapon in World War I. It can irritate the respiratory tract, damage the skin, cause dermatitis and urticaria, adhere to the eyes, inhale high concentrations of it vapor, and even cause temporary chest tightness, bronchitis, and pulmonary edema. Although it has certain risks and toxicity, it is also an important organic synthetic industrial raw material, widely used in the manufacture of foaming agents, as well as foaming agents, yeast preservatives, and so on.
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CF |
C7H7Br |
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EM |
170 |
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MW |
171 |
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m/z |
170 (100.0%), 172 (97.3%), 171 (7.6%), 173 (7.4%) |
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EA |
C, 49.16; H, 4.13; Br, 46.72 |
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The main preparation methods of Benzyl Bromide 99% are:
(1) Toluene reacts with bromine. First heat toluene to 50 ° C, then add bromine, and the reaction temperature is 75 ~ 80C. The reaction time was 6h and benzyl bromide was prepared.
(2) Benzyl alcohol reacts with brominating reagent. The main bromination reagents are dibromo sulfoxide and phosphorus tribromide, and the reaction conditions are different with different reagents.
When reacting dibromo sulfoxide with benzyl alcohol, pyridine and dibromo sulfoxide must be slowly added dropwise to the benzyl alcohol solution in the presence of dichloroethane and argon, and then refluxed for 3h to prepare benzyl bromide after treatment.
The reaction between phosphorus tribromide and benzyl alcohol is carried out in the presence of dry diethyl ether
The temperature is controlled at 0C.
(3) Prepared by reductive bromination of aromatic aldehydes. The corresponding it was obtained by reacting aromatic aldehydes with equimolar amounts of isobaric pinyl boron dibromide (prepared from hbbr2-sme2 and a ~ pinene) in Hexane at room temperature for several hours, and after appropriate post-treatment.
Benzyl Bromide 99% is an aromatic compound in which the benzene ring is replaced by a bromomethyl group. Its chemical formula is C7H7Br and it is one of the irritating compounds in the benzyl halide class. Despite its strong irritant and certain toxicity, it has a wide range of applications in multiple fields.
1. Benzylation reagent
One of the most important uses in organic synthesis is as a benzylation reagent. It can effectively carry out benzylation reactions on various heteroatom functional groups under various conditions, which is one of the key steps in constructing complex molecular structures in organic synthesis. For example, it can react with functional groups such as alcohols, amines, phenols, etc. to generate corresponding benzylation products, which have wide applications in the fields of pharmaceuticals, pesticides, dyes, etc.
2. Initiators and catalysts
In polymerization reactions, it is also used as an initiator or catalyst. For example, in atom transfer radical polymerization (ATRP) reactions, benzyl bromide can act as an initiator to undergo polymerization reactions with monomers to produce polymer materials. In addition, it can also participate in Menshutkin reactions and form compounds with specific functions.
Applications in the Chemical Industry
1. Manufacturing of foaming agent
It is one of the important raw materials for manufacturing foaming agents. Foaming agents are widely used in construction, automobile, packaging and other fields to manufacture lightweight materials such as foamed plastics and foam rubber. These materials have excellent thermal insulation, sound insulation, shock absorption and other properties, and are one of the indispensable materials in modern industry.
2. foam agent and yeast preservative
In addition to foaming agent, it can also be used as foam agent and yeast preservative. In the food industry, yeast preservatives are used to prevent excessive fermentation of food and maintain its taste and quality. Foam agent is used to manufacture various foam products, such as foam packaging materials, foam cleaner, etc.
The greatest use of benzyl bromide is as a reagent for the benzylation of heteroatomic functional groups, which can effectively benzylate various heteroatomic functional groups under various conditions, thus providing a wide range of uses in organic synthesis, mainly as a protecting group.
Benzylation of alcohols and phenols:
In ether or DMF solvents, alcohols can be treated with NaH or KH to give alkoxides, which in turn undergo Williamson reaction with benzyl bromide.
At low temperatures, benzylation reactions occur preferentially with primary alcohols compared to secondary alcohols.
In addition to the NaH and KH alkaline systems, KF/Al or Ag2O can also be used as alkaline systems to induce benzylation of alcohols.
Phenolic compounds are more acidic than fatty alcohol compounds, so benzylation of phenols can be achieved in the presence of a weak base (e.g. potassium carbonate).
Benzyl bromide, also known as benzyl bromide or alpha bromotoluene, is a halogenated benzyl compound in which the benzene ring is replaced by a bromomethyl group. It has an aromatic odor in its colorless liquid form, but is highly volatile and irritating, posing significant hazards to the eyes, respiratory tract, and skin. Although it has been mistakenly used as a chemical weapon in history due to its tear gas effect, in modern industry, benzyl bromide has become a key raw material in fields such as organic synthesis, pharmaceuticals, materials science, and agriculture due to its unique chemical properties.
It is an indispensable "tool reagent" in organic synthesis, and its core value lies in its use as a benzylation reagent to change the structure and properties of target molecules by introducing benzyl (- CH ₂ -). Specific applications include:
1. Preparation of esters, ethers, and acyl chlorides
Can react with alcohols and phenolic compounds to produce benzyl esters or ethers, such as reacting with phenol to prepare benzyl phenyl ether, which is used as an intermediate in fragrances and dyes; Reacting with carboxylic acid to generate benzyl chloride, further synthesizing drugs or polymer materials.
2. Benzylation of heteroatom functional groups
Under alkaline conditions (such as sodium hydroxide or potassium carbonate), benzyl protection can be applied to heteroatom functional groups containing nitrogen, oxygen, and sulfur (such as amino, hydroxyl, and thiol groups).
For example:
Drug synthesis: In the synthesis of antidepressant fluoxetine, benzyl bromide is used to protect the amino group, prevent its involvement in side reactions, and improve synthesis efficiency.
Natural product modification: Benzylation of biomolecules such as sugars and amino acids can enhance their stability or alter their solubility, facilitating subsequent structural analysis.
3. Foaming agent and foam agent manufacturing
Nitrogen and other gases are generated through decomposition, which are used as foaming agents for polyurethane foam plastics, giving the materials lightweight and heat insulation characteristics, and are widely used in building insulation and packaging materials.
4. Catalysts and additives
Light stabilizer: Benzyl bromide derivatives can absorb ultraviolet radiation and prevent polymer materials (such as plastics and rubber) from aging.
Resin curing agent: Introducing benzyl structure into epoxy resin can adjust the curing speed and mechanical properties.
Flame retardant: Compound of benzyl bromide and phosphorus compounds, used for flame retardant treatment of electronic device casings to enhance safety.
Pharmaceutical field: from drug synthesis to disease treatment
Plays a dual role in the pharmaceutical industry: as a key intermediate for synthesizing drugs, it is also an ingredient that directly exerts pharmacological activity.
1. Synthesis of drug intermediates
Antiepileptic drugs: In the synthesis of carbamazepine, benzyl bromide is used to construct a benzodiazepine skeleton, enhancing the inhibitory effect of the drug on neurons.
Antidepressants: In the synthesis of selective serotonin reuptake inhibitor (SSRI) antidepressants such as sertraline, benzyl bromide is used to protect the amino group or introduce the benzyl side chain.
Antihypertensive drugs: In the synthesis of angiotensin converting enzyme inhibitors (ACEI), benzyl bromide is used to construct thiol or carboxyl protecting groups.
2. Development of diagnostic reagents
Plasma prothrombin time reagent: Benzyl bromide derivatives can simulate coagulation factor activity and are used to detect blood coagulation function, assist in the diagnosis of liver disease, or monitor anticoagulant therapy.
Angiotensin converting enzyme reagent: used to measure ACE activity and evaluate the effectiveness of enzyme inhibition therapy in hypertensive patients.
3. Animal anesthetics
Derivatives of benzyl bromide, such as trimethylbenzyl ammonium bromide, can produce anesthetic effects by inhibiting the central nervous system. They are commonly used for short-term anesthesia in experimental animals, such as mice and rats, and are convenient for surgical or sampling procedures.
4. Anti tumor research
The latest research shows that it can inhibit tumor cell proliferation and migration, and induce apoptosis. The mechanism may involve:
DNA damage: Metabolism in the body produces active intermediates that bind to DNA, leading to strand breaks or base modifications.
Cell cycle arrest: By downregulating the expression of cell cycle proteins (such as Cyclin D1), tumor cells are arrested in the G1 phase.
Chemotherapy sensitization: Combined with chemotherapy drugs such as cisplatin, it can enhance the killing effect on tumor cells and reduce drug resistance.
Agricultural field: from seed treatment to crop protection
The application in agriculture focuses on seed disinfection and crop protection, and its derivatives exert bactericidal effects by disrupting microbial cell membranes or inhibiting enzyme activity.
1. Disinfection of hatching eggs before hatching
Benzylammonium bromide (benzalkonium bromide, a derivative of benzyl bromide) is a cationic surfactant that can kill both Gram positive and Gram negative bacteria (such as Escherichia coli and Salmonella) on the surface of hatching eggs, reducing the risk of bacterial infection during the hatching process. However, it should be noted that its effectiveness against viruses is limited, and comprehensive disinfection should be carried out by combining physical methods such as ultraviolet irradiation.
2. Crop fungicides
Benzyl bromide derivatives (such as benzyl trimethylammonium bromide) can be used to control fungal diseases (such as gray mold and downy mildew) in fruit trees (such as apples and citrus) and vegetables (such as tomatoes and cucumbers). Its mechanism of action includes:
Cell membrane disruption: By binding positively charged fungal cell membrane phospholipids, membrane permeability increases and cell contents leak.
Enzyme activity inhibition: Inhibits key enzymes such as chitinase and blocks fungal cell wall synthesis.
3. Pesticide intermediate
Can be used to synthesize pyrethroid insecticides (such as deltamethrin), which achieve efficient insecticidal effects by interfering with insect axon conduction. Its advantage lies in low toxicity to mammals, easy degradation, and in line with the development trend of green pesticides.
The benzyl structure of benzyl bromide can endow materials with special properties, promoting innovative applications of polymer materials and functional materials.
1. Polymer material modification
Polymer cross-linking agent: react with polyvinyl alcohol (PVA) to introduce cross-linking structure to improve the water resistance and mechanical strength of the material, which is used for medical dressings or hydrogels.
Side chain modification: Introducing benzyl bromide into the polystyrene (PS) side chain can further functionalize (such as grafting fluorescent groups) and prepare fluorescent probes or sensors.
2. Synthesis of functional materials
Ionic liquid: Reacts with imidazole compounds to synthesize low melting point, high conductivity ionic liquids, which are used as battery electrolytes or catalyst carriers.
Metal organic frameworks (MOFs): As ligands, they self assemble with metal ions (such as zinc and copper) to form porous MOF materials for gas adsorption (such as CO ₂ capture) or catalytic reactions.
FAQ
What is benzyl bromide used for?
Benzyl bromide is an aromatic halide that is mainly used as a protecting agent for protecting hydroxy group of alcohols via O-benzylation reaction.
Is benzyl bromide safe?
Handle with extreme caution. * Benzyl Bromide is a HIGHLY CORROSIVE CHEMICAL and contact can severely irritate and burn the skin and eyes with possible eye damage.
Is benzyl bromide a liquid or solid?
Benzyl bromide appears as a colorless liquid with an agreeable odor. Toxic by inhalation and by skin absorption. It is slightly soluble in water and denser than water (density 1.44 g / cm3 (Aldrich)).
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