BENZYLTOLUENE

Benzyltoluene is a high-boiling aromatic hydrocarbon supplied commercially as a mixture of ortho-, meta-, and para-benzyltoluene isomers.
Its low vapour pressure, low viscosity, broad liquid range, thermal stability, and electrical insulating behaviour support its use in heat-transfer fluids, dielectric liquids, and liquid organic hydrogen carrier systems.

CHEMICAL IDENTITY AND COMMON NAMES

Commercial Benzyltoluene is the reaction mass of 1-benzyl-2-methylbenzene, 1-benzyl-3-methylbenzene, and 1-benzyl-4-methylbenzene.
Each positional isomer contains two benzene rings connected through a methylene group and carries one methyl substituent.
The individual components are 2-benzyltoluene, CAS 713-36-0, 3-benzyltoluene, CAS 620-47-3, and 4-benzyltoluene, CAS 620-83-7.
CAS 27776-01-8 identifies the commercial isomeric mixture rather than one isolated positional isomer.
Benzyltoluene should not be confused with dibenzyltoluene.
Dibenzyltoluene contains an additional benzyl substituent, has the molecular formula C21H20, and exhibits a higher boiling range and viscosity.

Synonyms and Common Names: Benzyltoluene mixed isomers, Benzyltoluene isomeric mixture, Benzyltoluol, Monobenzyl toluene, Monobenzyltoluene, MBT, BT, Methyl(phenylmethyl)benzene, Benzene methyl(phenylmethyl)-, Methane phenyltolyl-, Methyldiphenylmethane, Methyl diphenyl methane, Phenyltolylmethane, Tolylphenylmethane, Phenylmethyl toluene, Benzylmethylbenzene, Reaction mass of 1-benzyl-2-methylbenzene and 1-benzyl-3-methylbenzene and 1-benzyl-4-methylbenzene

TECHNICAL IDENTIFICATION

CAS Number: 27776-01-8
EC / EINECS Number: 248-654-8
Molecular Formula: C14H14
Molar Mass: 182.26 g/mol
Chemical Family: Diarylmethane aromatic hydrocarbons
Composition: Mixture of 2-, 3-, and 4-benzyltoluene
Physical Form: Liquid at ambient temperature

PHYSICAL AND CHEMICAL PROPERTIES

Appearance: Clear, colourless to light-yellow liquid
Odour: Weak aromatic odour
Density: Approximately 0.995 g/cm³ at 20 °C
Boiling Range: Approximately 280–290 °C at 1013 hPa
Melting / Freezing Range: Approximately -80 to -70 °C
Flash Point: Approximately 137 °C, closed cup
Autoignition Temperature: Approximately 510 °C
Vapour Pressure: Approximately 0.66 Pa at 20 °C and 1.01 Pa at 25 °C
Water Solubility: Approximately 0.038 mg/L at 20 °C
Log Pow: 4.31–4.40 at 20 °C
Kinematic Viscosity: Approximately 4.0 mm²/s at 20 °C
Kinematic Viscosity: Approximately 2.56 mm²/s at 40 °C
Dielectric Constant: Approximately 2.7 at 23 °C for a refined heat-transfer grade
Solubility in Organic Media: Soluble in aromatic hydrocarbons and many non-polar organic solvents
Volatility: Low at ambient temperature
Combustibility: Combustible when sufficiently heated but not classified as a flammable liquid under CLP

The low-temperature behaviour of Benzyltoluene depends strongly on isomer distribution, nucleation, and thermal history.
Crystallization testing is therefore an important grade-selection parameter in addition to melting range and pour point.

FUNCTIONAL CHARACTERISTICS

The two aromatic rings provide molecular polarizability, thermal stability, non-polar solvency, and useful dielectric behaviour.
The methylene bridge retains molecular flexibility, helping the commercial isomer mixture remain fluid over a broad temperature range.

Its high boiling range and very low ambient vapour pressure reduce evaporative loss in enclosed thermal systems.
Low viscosity supports circulation, pumping, heat exchange, impregnation, and cold-start performance.

Benzyltoluene is strongly hydrophobic and practically insoluble in water.
Water, ionic residues, polar contaminants, and suspended particles can nevertheless impair its performance in electrical applications.

The aromatic rings undergo reversible catalytic hydrogenation to produce perhydrobenzyltoluene.
This reaction enables Benzyltoluene to function as the hydrogen-lean component of a liquid organic hydrogen carrier cycle.

PRODUCTION AND COMMERCIAL FORM

Benzyltoluene is manufactured principally through Friedel–Crafts alkylation of toluene with benzyl chloride.
Ferric chloride, aluminium chloride, other Lewis acids, or suitable solid-acid catalysts can promote the reaction.
The process forms ortho-, meta-, and para-benzyltoluene together with smaller quantities of dibenzyltoluene and heavier aromatic products.
Hydrogen chloride is generated as a reaction by-product.

Excess toluene is recovered, catalyst and chlorinated residues are removed, and vacuum or fractional distillation separates the monobenzyltoluene fraction from light components and heavier benzylated products.
The positional isomers are normally retained as a mixture because their combined fluid behaviour is commercially useful.
Benzyltoluene is supplied as an industrial intermediate, a refined synthetic heat-transfer fluid, an electrical-grade fluid component, or a constituent of formulated Benzyltoluene and dibenzyltoluene blends.

APPLICATIONS AND INDUSTRIES

Closed-loop heat-transfer systems

Benzyltoluene is used as a synthetic, non-aqueous heat-transfer medium in closed circulation systems.
Its high boiling range, low viscosity, low vapour pressure, and thermal stability enable efficient heat delivery without the pressures required by steam at comparable temperatures.
Applications include heating and cooling of chemical and pharmaceutical reactors, temperature-control units, heat exchangers, pilot plants, specialty-chemical equipment, and processes that alternate between heating and cooling cycles.

Engineered heat-transfer grades are specified with recommended bulk temperatures near 330 °C, extended pressurized operation up to approximately 360 °C, and film-temperature limits near 380 °C.
The selected grade’s bulk-temperature, film-temperature, pressure, and minimum-startup limits form the engineering basis for each installation.

Electrical insulation and capacitor fluids

Benzyltoluene is used as a dielectric impregnation liquid and as a major component of formulated electrical insulating oils.
Established applications include high-voltage capacitors and insulating-fluid systems for transformers, high-voltage cables, bushings, tap changers, rectifiers, and harmonic filters.
Its low viscosity assists penetration into tightly wound dielectric structures and promotes heat removal from electrically stressed regions.
Its aromatic character also provides useful hydrogen-gas absorption behaviour, helping formulated fluids manage gases generated by electrical discharge.
Benzyltoluene may be blended with dibenzyltoluene, diphenylethane, mineral oil, or selected natural and synthetic esters.
Blend composition is used to control viscosity, crystallization, dielectric performance, gas absorption, and low-temperature fluidity.
Electrical grades require exceptionally low moisture, chloride, acidity, polar contamination, and particulate content.
These parameters directly influence breakdown voltage, dissipation factor, volume resistivity, and long-term insulation performance.

Liquid organic hydrogen carrier systems

Benzyltoluene and perhydrobenzyltoluene form a reversible liquid organic hydrogen carrier pair.
Hydrogen is chemically stored by catalytic hydrogenation of the aromatic rings and released through catalytic dehydrogenation.
Complete hydrogenation provides a hydrogen storage capacity of approximately 6.2% by weight.
Both forms remain liquid over a broad temperature range and can be handled in tanks, pumps, pipelines, and other infrastructure designed for compatible liquid hydrocarbons.
The relatively low viscosity of the Benzyltoluene system supports pumping and heat transfer, particularly under colder operating conditions.
Benzyltoluene is also combined with dibenzyltoluene-based carriers to improve the low-temperature viscosity of hydrogen-rich mixtures.

Chemical intermediate and specialty process fluid

Benzyltoluene serves as an intermediate in aromatic synthesis and as a feedstock for further benzylation to dibenzyltoluene and related diarylmethane products.
Its hydrophobicity, aromatic solvency, low volatility, and high boiling range also support specialised use as a process carrier or reaction medium for non-polar organic materials.
These applications are conducted in contained industrial systems with effective exposure and environmental controls.

GRADE SELECTION AND PRODUCT SUITABILITY

Heat-transfer grades emphasize controlled viscosity, boiling distribution, low acidity, low moisture, colour stability, thermal ageing performance, and limited light and heavy ends.
Dibenzyltoluene content influences boiling range, viscosity, thermal behaviour, and low-temperature pumpability.
Electrical grades require rigorous control of water, particles, chloride, total chlorine, ionic contamination, acidity, and polar oxidation products.
Isomer distribution and blend composition are also important where low-temperature crystallization resistance is required.

Liquid organic hydrogen carrier grades require tight control of sulphur, halogens, metals, water, oxygenated compounds, and other catalyst poisons.
Gas-chromatographic composition, hydrogenation response, cycling stability, and by-product formation are important evaluation parameters.

Intermediate grades are selected principally by Benzyltoluene assay, isomer profile, residual toluene, benzyl chloride, total chlorine, and dibenzyltoluene content.

FORMULATION AND PROCESS CONSIDERATIONS

Heat-transfer systems should be clean, dry, and free from incompatible residues before charging.
Air removal and inert-gas blanketing of the expansion space limit oxidation during high-temperature service.

Excessive film temperature can produce low-boiling degradation products through thermal cracking.
Oxidation and condensation reactions can generate acidity, colour, sludge, and high-boiling material.
Routine analysis of viscosity, acidity, flash point, light ends, and high-boiling residue provides a practical assessment of fluid condition.

Steel and stainless steel are suitable construction materials.
Seals, gaskets, hoses, coatings, and pump components should be selected for service with aromatic hydrocarbons.

Electrical impregnation processes benefit from fine filtration, vacuum drying, and degassing.
Preventing moisture and particulate contamination preserves dielectric strength and improves penetration into film and paper insulation systems.

Low-temperature designs should use crystallization and storage-stability data alongside viscosity and pour point.
Isomer balance and compatible aromatic blending can reduce crystal formation during prolonged cold exposure.

Hydrogen-carrier processes require dedicated catalytic hydrogenation and dehydrogenation equipment.
Catalyst protection depends on low concentrations of sulphur, halogens, metals, oxygenated impurities, and particulate matter.

QUALITY, SPECIFICATIONS AND DOCUMENTATION

Identity and Assay: Gas chromatography
Isomer Distribution: Ortho-, meta-, and para-benzyltoluene profile
Light Components: Residual toluene and other low-boiling compounds
Heavy Components: Dibenzyltoluene and higher benzylated material
Chlorine Profile: Residual benzyl chloride, organic chlorine, and extractable chloride
Water Content: Karl Fischer analysis
Acidity: Acid or neutralization number
Colour: APHA or Hazen colour
Density: Controlled at a stated temperature
Viscosity: Kinematic viscosity at the application temperature
Distillation: Initial boiling point, boiling range, and high-boiling residue
Low-Temperature Performance: Freezing range, pour point, and crystallization behaviour
Thermal Performance: Ageing stability, light-end formation, and high-boiling residue
Electrical Performance: Breakdown voltage, dielectric constant, dissipation factor, and volume resistivity
LOHC Performance: Catalyst-compatible impurity profile and hydrogenation-cycle behaviour
Particulate Control: Cleanliness and filtration status

A Certificate of Analysis records lot-specific quality results.
The Technical Data Sheet defines the grade’s functional and operating characteristics.
The Safety Data Sheet provides classification, exposure controls, transport information, and emergency procedures.

SAFETY AND REGULATORY CONSIDERATIONS

Signal Word: Danger
Skin Irritation: Category 2
Reproductive Toxicity: Category 1B
Aspiration Hazard: Category 1
Aquatic Chronic Hazard: Category 1
H304: May be fatal if swallowed and enters airways
H315: Causes skin irritation
H360FD: May damage fertility and may damage the unborn child
H410: Very toxic to aquatic life with long-lasting effects

Swallowing followed by aspiration into the lungs can cause chemical pneumonitis or asphyxiation.
Repeated or prolonged skin contact can remove natural oils and cause irritation or dermatitis.

Its very low water solubility does not eliminate environmental risk.
High hydrophobicity, limited biodegradation, and bioaccumulation potential make strict containment essential.

Transport Classification: UN 3082
Proper Shipping Name: Environmentally hazardous substance, liquid, n.o.s.
Transport Class: 9
Packing Group: III
Marine Pollutant: Yes

FIRST AID

Inhalation: Move the affected person to fresh air and obtain medical attention if breathing difficulty, irritation, or other symptoms occur.
Skin Contact: Remove contaminated clothing and wash the skin thoroughly with soap and water.
Eye Contact: Rinse cautiously with clean water for at least 15 minutes, removing contact lenses when easy to do, and obtain medical attention if irritation persists.
Ingestion: Do not induce vomiting and obtain immediate medical assistance because of the aspiration hazard.
Exposure Concern: Obtain medical advice following exposure or concern relating to reproductive toxicity.
Note to Physicians: Treatment should address the risk of aspiration and chemical pneumonitis.

HANDLING AND STORAGE

Use enclosed transfer systems and effective general or local exhaust ventilation.
Avoid inhaling vapour, heated fumes, mist, or aerosol.

Wear chemical-resistant gloves, protective clothing, and safety glasses or face protection.
Wash thoroughly after handling and remove contaminated clothing promptly.

Keep away from heat, ignition sources, sparks, direct sunlight, and strong oxidizing agents.
Ground and bond containers and transfer equipment to control static electricity.

Store locked up in tightly closed, upright containers in a cool, dry, well-ventilated area.
Protect the material from moisture, contamination, ultraviolet light, and unnecessary contact with air.

FIRE AND SPILL RESPONSE

Use dry chemical powder, carbon dioxide, or water spray or fog for fire control.
Do not use a high-pressure water jet.
Combustion and thermal decomposition can generate carbon monoxide, carbon dioxide, hydrocarbons, benzene, and dense smoke.

Evacuate unnecessary personnel, ventilate the area, and eliminate ignition sources during spill response.
Contain the liquid with sand or another inert absorbent and collect it in a compatible closed waste container.
Prevent the product and contaminated firefighting water from entering drains, soil, surface water, or groundwater.

PACKAGING AND PROCUREMENT CONSIDERATIONS

Benzyltoluene is commonly supplied in coated or compatible steel drums, intermediate bulk containers, and bulk tank shipments.
Packaging should remain clean, dry, tightly sealed, and suitable for environmentally hazardous liquids.

Procurement planning should define the intended use, required assay, isomer distribution, allowable dibenzyltoluene content, water limit, chlorine profile, acidity, low-temperature behaviour, and packaging quantity.
Heat-transfer, electrical, intermediate, and hydrogen-carrier applications require different combinations of analytical and performance controls.

For Benzyltoluene grade selection, specifications, application requirements, documentation, packaging, and supply planning, contact Ataman Kimya.
+90 216 577 10 10
info@atamankimya.com