3-Methyl-1-pentene (760-20-3) Physical and Chemical Properties
3-Methyl-1-pentene
A branched aliphatic olefin used as a nonpolar feedstock and intermediate in specialty chemical syntheses, formulation development and analytical standards preparation.
| CAS Number | 760-20-3 |
| Family | Branched alkenes (aliphatic olefins) |
| Typical Form | Colorless liquid |
| Common Grades | EP |
3-Methyl-1-pentene is a C6 alkenic hydrocarbon of the branched terminal-olefin structural class. The molecule has the connectivity of a 1-alkene with a methyl substituent at C‑3 (IUPAC name: 3-methylpent-1-ene) and molecular formula \(C_6H_{12}\). Structurally it contains a monosubstituted terminal carbon–carbon double bond conjugated only to sp^3 carbons, a nonpolar hydrocarbon skeleton with low polar surface area, and limited conformational flexibility (rotatable bond count = 2). Key computed descriptors include molecular weight \(84.16\,\mathrm{g}\,\mathrm{mol}^{-1}\), XLogP3-AA = 2.7, exact mass 84.093900383 and topological polar surface area 0.
Electronically the terminal C=C is the primary reactive locus: it behaves as a typical electron-rich alkene undergoing electrophilic additions, transition-metal catalysed insertion-type reactions, and radical additions. The molecule is nonpolar and lipophilic (moderately high log P), insoluble in water, and is expected to partition into organic phases and hydrocarbon mixtures. As a light branched alkene, it is a volatile, low-boiling hydrocarbon under ambient conditions and shows the flammability and oxidation behaviour characteristic of small-chain alkenes (readily forms combustion products and can be oxidized, polymerized or hydrohalogenated under appropriate conditions).
Common commercial grades reported for this substance include: EP.
Physical Properties
The compound is a branched C6 terminal alkene with the following computed identifiers: molecular formula \(C_6H_{12}\); molecular weight \(84.16\,\mathrm{g}\,\mathrm{mol}^{-1}\); SMILES: CCC(C)C=C; InChI: InChI=1S/C6H12/c1-4-6(3)5-2/h4,6H,1,5H2,2-3H3; InChIKey: LDTAOIUHUHHCMU-UHFFFAOYSA-N. Computed descriptors include XLogP3-AA = 2.7, exact/monoisotopic mass 84.093900383, topological polar surface area = 0, rotatable bond count = 2 and reported complexity values ~37.
Chromatographic characterization: multiple Kovats retention index measurements on non-polar GC columns are reported (selected standard non-polar values: 556.5, 554, 548, 557.6, 562.7; selected semi-standard non-polar values: 545, 549.7, 549, 551.8, 561.1), indicating consistent elution behaviour typical for branched C6 alkenes.
Density and Phase
No experimentally established value for density is available in the current data context. In practice, branched C6 alkenes are liquids at ambient temperature with densities lower than water (typical of nonpolar hydrocarbons) and a vapour pressure high enough to make them volatile; they are handled as volatile organic liquids.
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 class, C6 terminal alkenes are low-boiling (volatile) liquids and their boiling points are lower than longer-chain hydrocarbons and somewhat comparable to isomeric hexenes.
Vapor Pressure
No experimentally established value for this property is available in the current data context. Class-level behavior: terminal alkenes of this size exhibit appreciable vapour pressures at ambient temperature and present inhalation and flammability exposure routes in open handling.
Viscosity
No experimentally established value for this property is available in the current data context. Typical branched C6 alkenes have low kinematic viscosities, similar to other light aliphatic hydrocarbons.
Chemical Properties
The dominant functional group is a terminal alkene (vinyl group) giving reactivity typical of monosubstituted alkenes: electrophilic additions (hydrohalogenation, hydration under acid or catalytic conditions), hydroboration–oxidation, epoxidation, oxidative cleavage, radical additions and polymerization under initiation. The terminal double bond is also a substrate for transition-metal catalysed transformations such as hydroformylation, alkoxycarbonylation, and other Markovnikov/anti‑Markovnikov hydrofunctionalizations; photoinduced and metal-catalysed hydrofunctionalization methods have been demonstrated on general alkene substrates.
Nucleophilic or strongly basic conditions that remove allylic protons can enable isomerization to internal alkenes; hydrogenation converts the alkene to saturated branched hexane isomers. Oxidative conditions (ozonolysis, permanganate) will cleave the double bond to yield lower molecular weight carbonyl fragments. Under combustion, complete oxidation produces \(CO_2\) and \(H_2O\) while incomplete combustion yields carbon monoxide, soot and other partially oxidized hydrocarbons.
Flammability and Combustion
The substance is classified as a highly flammable liquid and vapour (classification: Flam. Liq. 2; hazard statement H225). It poses an acute fire risk in vapor form because vapours can travel to an ignition source and flash back. No specific flash point or flammability limits are provided in the current data context. During combustion, expect the usual hydrocarbon oxidation products; fires involving this material require application of standard hydrocarbon firefighting measures (appropriate extinguishing media, personnel protection and thermal decomposition precautions).
Reactivity and Typical Transformations
Typical chemical transformations exploit the terminal C=C double bond: electrophilic addition, radical addition, hydrofunctionalization (including hydroformylation and alkoxycarbonylation), hydrometallation and catalytic cross-coupling strategies following functionalization. The molecule can undergo polymerization under radical or coordination-catalysed conditions and may isomerize to internal alkenes under acid or base catalysis. It is chemically stable toward weak nucleophiles and non-oxidizing conditions but susceptible to oxidation, halogenation and hydrogenation.
Identifiers and Synonyms
Registry Numbers and Codes
- CAS RN: 760-20-3
- Related CAS/alternative identifiers appearing in records: 26702-69-2; related CAS: 25266-25-5; deprecated CAS: 207352-01-0
- European Community (EC) Number: 212-076-4
- UNII: WT3LD9LU1F
- DSSTox Substance ID: DTXSID20870762
- Nikkaji Number: J43.508B
- NSC Number: 73909
- InChI: InChI=1S/C6H12/c1-4-6(3)5-2/h4,6H,1,5H2,2-3H3
- InChIKey: LDTAOIUHUHHCMU-UHFFFAOYSA-N
- SMILES: CCC(C)C=C
Synonyms and Structural Names
Depositor-supplied synonyms and name variants include (selection shown as provided):
3-METHYL-1-PENTENE; 3-Methylpent-1-ene; 1-Pentene, 3-methyl-; Pentene, 3-methyl-; 2-Vinylbutane; sec-Butylethene; 3-methylpentene-1; 1-Pentene,3-methyl-; C2H5CH(CH3)CH=CH2; 1-Pentene, 3-methyl-(8CI). Additional vendor/registry labels recorded: NSC73909; UNII-WT3LD9LU1F; EINECS 212-076-4.
(Exact synonyms and identifier lists above are reproduced from available submitted identifiers and depositor-supplied synonyms.)
Industrial and Commercial Applications
Use as Solvent or Fuel Component
No concise, product-specific application summary is available in the current data context; however, from a class perspective, branched light alkenes such as 3-methyl-1-pentene are commonly used as synthetic intermediates in organic synthesis and as constituents of hydrocarbon mixtures. They may be incorporated into fuel formulations or petrochemical streams as minor components, and they can serve as feedstocks for catalytic hydrofunctionalization, hydroformylation and other value‑adding transformations to produce oxygenates or functionalized intermediates.
Representative Use Scenarios
Representative scenarios include use as: - Feedstock for catalytic conversion to aldehydes, alcohols or esters via hydroformylation/alkoxycarbonylation pathways. - Starting material for selective hydrofunctionalization (hydroboration, hydroamination, hydrofluorocarbofunctionalization) to introduce heteroatoms or functional groups at the terminal position. - Analytical standard or reference component for gas chromatography and mass spectrometry libraries (GC–MS fragmentation patterns and Kovats retention index data are available).
If a specific application or formulation is required for procurement or process design, selection should be guided by purity grade, impurity profile and compatibility with downstream catalysts or process conditions.
Safety and Handling Overview
Flammability Hazards
3-Methyl-1-pentene is classified with the signal word “Danger” for flammability. Reported GHS hazard statements associated with commercial classifications include: H225 (Highly flammable liquid and vapour). Other reported hazard statements associated with some commercial notifications include aspiration hazard (H304), skin and eye irritation (H315, H319) and respiratory irritation (H335) depending on formulation and impurity profile. Vapour accumulation in confined spaces can create explosive mixtures; controls to prevent ignition sources and reduce vapour concentration are necessary.
Storage and Handling Considerations
Handle as a flammable volatile hydrocarbon: store in tightly closed, properly labelled containers in a cool, well-ventilated area away from heat, sparks, open flame and oxidizers. Use grounding and bonding during transfer to prevent electrostatic discharge. For process-scale handling consider inerting (nitrogen) where the vapour space and reaction conditions can generate flammable atmospheres or where oxidation/polymerization is a risk. Use appropriate personal protective equipment (chemical-resistant gloves, eye protection, flame-resistant lab coat) and ensure engineering controls (local exhaust ventilation, explosion-proof electrical fittings) are in place. Avoid prolonged or repeated inhalation of vapours and contact with skin or eyes. For detailed hazard, transport and regulatory information, users should refer to the product-specific Safety Data Sheet (SDS) and local legislation.
