1,3-Dimethylcyclohexane (591-21-9) Physical and Chemical Properties
1,3-Dimethylcyclohexane
A saturated C8 cycloalkane typically supplied as a cis/trans mixture and used as a non‑polar solvent and intermediate in specialty chemical manufacture and R&D.
| CAS Number | 591-21-9 |
| Family | Aliphatic hydrocarbons (cycloalkanes) |
| Typical Form | Colorless liquid |
| Common Grades | EP, JP |
1,3-Dimethylcyclohexane is an aliphatic, saturated cycloalkane in which two methyl substituents occupy the 1- and 3-positions on a cyclohexane ring. The molecular formula is \(C_8H_{16}\) and the structure is a nonpolar, fully saturated hydrocarbon lacking heteroatoms or polar functional groups. Stereochemically this system exists as cis and trans stereoisomers (relative methyl orientations on the ring); the connectivity and presence of stereochemical isomers influence conformational preferences but do not introduce hydrogen-bonding capability. Computed descriptors indicate zero topological polar surface area and no hydrogen-bond donors or acceptors, consistent with purely van-der-Waals intermolecular interactions.
Electronically and physicochemically the compound behaves as a typical C8 aliphatic hydrocarbon: low polarity, lipophilic character (XLogP3 \(\approx\) \(3.8\)), and limited chemical reactivity under mild conditions. Hydrolytic and acid–base chemistry are not applicable; oxidative or radical processes are the principal routes to chemical transformation (combustion, radical halogenation, catalytic oxidation under forcing conditions). Volatility is significant for a C8 saturated hydrocarbon and the substance is a colorless liquid under normal ambient conditions.
From an application perspective, this material is encountered as part of isomeric mixtures used industrially as nonpolar solvents and as intermediates in hydrocarbon processing and specialty solvent blends. Common commercial grades reported for this substance include: EP, JP.
Physical Properties
Density and Phase
1,3-Dimethylcyclohexane is described as a colorless liquid at ambient temperature and pressure, consistent with C8 saturated hydrocarbons. No experimentally established numerical density value for this property is available in the current data context.
Melting Point
No experimentally established value for this property is available in the current data context.
Boiling Point
No experimentally established value for this property is available in the current data context. As a general class-level remark, C8 cycloalkanes are moderately volatile liquids at ambient conditions and show boiling behavior typical of nonpolar hydrocarbons.
Vapor Pressure
Measured vapor pressure is \(21.4\,\mathrm{mmHg}\). This magnitude is consistent with a volatile aliphatic hydrocarbon at ambient-to-moderate temperatures and indicates appreciable vapor concentration potential under open-handling or warm conditions.
Viscosity
No experimentally established value for this property is available in the current data context.
Chemical Properties
Flammability and Combustion
1,3-Dimethylcyclohexane is a highly flammable liquid and vapor. It forms explosive mixtures with air and burns to produce typical combustion products of hydrocarbons (principally \(CO_2\) and \(H_2O\) under complete combustion; carbon monoxide and soot may form under oxygen-limited conditions). The substance is classified within hazard categories consistent with flammable liquids and may cause irritation to skin, eyes, and the respiratory tract; overexposure to vapor can lead to central nervous system effects (drowsiness, dizziness, headache, i.e., acute solvent syndrome). Environmental toxicity for aquatic organisms has been reported as a long-term hazard potential. Appropriate controls for ignition sources, adequate ventilation, and personal protective equipment are required when handling.
Reactivity and Typical Transformations
As a saturated hydrocarbon without functional groups, 1,3-dimethylcyclohexane is chemically inert to many common reagents under mild conditions. Characteristic reactivity pathways include: - Radical halogenation (substitution at alkyl positions) under photochemical or thermal initiation. - Catalytic dehydrogenation or selective oxidation under forcing, catalytic conditions to give unsaturated or oxygenated products. - Combustion under oxidizing conditions. Nucleophilic and electrophilic substitution reactions that rely on polar functional groups are not applicable. Chemical stability toward hydrolysis is high due to absence of hydrolyzable bonds.
Identifiers and Synonyms
Registry Numbers and Codes
- CAS RN: 591-21-9
- European Community (EC) number: 209-707-0
- ChEMBL ID: CHEMBL1952259
- DSSTox Substance ID: DTXSID10858731
Synonyms and Structural Names
- IUPAC name: 1,3-dimethylcyclohexane
- Other names/synonyms (selected, depositor-supplied): 1,3-DIMETHYLCYCLOHEXANE; Cyclohexane, 1,3-dimethyl-; m-Dimethylcyclohexane; Hexahydro-m-xylene; 1,3-Dimethylcyclohexane, cis + trans; 1,3-dimethyl-cyclohexane
- SMILES: CC1CCCC(C1)C
- InChI: InChI=1S/C8H16/c1-7-4-3-5-8(2)6-7/h7-8H,3-6H2,1-2H3
- InChIKey: SGVUHPSBDNVHKL-UHFFFAOYSA-N
- Molecular formula: \(C_8H_{16}\)
- Molecular weight: \(112.21\,\mathrm{g}\,\mathrm{mol}^{-1}\)
- Exact mass / Monoisotopic mass: 112.125200510
Industrial and Commercial Applications
Use as Solvent or Fuel Component
The substance is used as a nonpolar specialty solvent and as an intermediate in hydrocarbon processing. Its nonpolarity and lipophilicity make it suitable for dissolving nonpolar organic materials (hydrocarbon resins, oils, certain polymers) and for inclusion in solvent blends where high solvency for apolar solutes is required. It may also occur as a component in fuel or petrochemical streams where cyclic alkanes are present.
Representative Use Scenarios
Representative scenarios in industrial practice include usage as a special-purpose solvent in formulations where aromatic solvents are to be avoided, as a component of hydrocarbon mixtures in research and process chemistry, and as an intermediate in synthesis routes that employ saturated cycloalkanes as feedstocks. Selection for a process is typically driven by solvency requirements, vapor pressure/volatility constraints, and compatibility with downstream processing.
Safety and Handling Overview
Flammability Hazards
Handling requires recognition of significant fire and vapor inhalation hazards. Key controls include: - Avoidance of ignition sources (open flames, sparks, hot surfaces) and prevention of static discharge; use grounding and bonding for transfer operations. - Use of explosion-proof electrical equipment and intrinsically safe lighting in storage and handling areas where vapor accumulation is possible. - Engineering controls to limit vapor concentrations: local exhaust ventilation and closed-system transfer where feasible. - Personal protective equipment: chemical-resistant gloves, eye protection, and protective clothing; respirators when ventilation is inadequate and vapor concentrations may exceed occupational limits.
The substance can cause skin and eye irritation and may cause respiratory irritation or central nervous system effects at elevated exposures.
Storage and Handling Considerations
Store in tightly closed containers in a cool, well-ventilated area away from oxidizers, strong acids, and sources of ignition. Containers and transfer lines should be electrically bonded and grounded to reduce the risk of static-induced ignition. Secondary containment and spill-control materials appropriate for hydrocarbon liquids should be available. For detailed hazard, transport and regulatory information, users should refer to the product-specific Safety Data Sheet (SDS) and local legislation.
