2,4,4-Trimethyl-1-pentene

2,4,4-Trimethyl-1-pentene is primarily synthesized from isobutylene through an olefinic complex decomposition reaction. This process involves connecting two isobutylene molecules head-to-tail under specific conditions, typically in the presence of a catalyst . Common catalysts include acid and metal catalysts. The reaction is carried out under controlled temperature and pressure to ensure optimal results . The industrial production process includes the following steps:

Raw Material Pretreatment: Purifying and drying isobutylene to meet reaction requirements.

Reaction: Introducing pretreated isobutylene into a reactor to undergo the olefin complex decomposition reaction.

Product Separation and Purification: Separating and purifying the reaction products to obtain high-purity diisobutylene.

Catalyst Regeneration: Regenerating the used catalyst to restore its activity for reuse.

Hydrocracking for Catalyst Evaluation

TMP1 serves as a model compound for studying hydrocracking (HCG) catalysts. Sulfided CoMo catalysts cleave its C–C bonds under hydrogen pressure to produce lighter hydrocarbons like propane and isobutane . This reaction helps evaluate catalyst acidity and hydrogenation activity.

Reaction Conditions :

• Temperature: 250–400°C

• Pressure: Hydrogen-rich environment

• Products: Propane, isobutane, and smaller alkanes .

Ozonolysis in Flow Reactors

Ozonolysis of TMP1 generates ozonides, which decompose to carbonyl compounds. This reaction is studied under pseudo-first-order conditions to understand oxidative cleavage mechanisms .

Mechanistic Pathway :

• Ozone addition to the double bond → Ozonide formation.

• Decomposition → Aldehydes/ketones (e.g., formaldehyde, 2,2-dimethylpropanal) .

Liquid-Phase Oxidation

Oxidation of TMP1 with molecular oxygen yields epoxides and hydrogen peroxide, highlighting its utility in peroxide synthesis .

Key Observations :

• Epoxidation occurs selectively at the double bond.

• Byproduct: Hydrogen peroxide (H₂O₂) .

Isomerization to 2,4,4-Trimethyl-2-pentene (TMP2)

TMP1 isomerizes to TMP2 under acidic or thermal conditions. Contrary to typical alkene stability trends, equilibrium favors TMP1 due to steric strain in TMP2 .

Table 1: Equilibrium Constants for Isomerization

Thermodynamic Data :

• ΔH° = 3.51 ± 0.03 kJ/mol (endothermic)

• ΔS° = -0.47 ± 0.10 J/mol·K .

Acid-Catalyzed Dimerization

TMP1 is synthesized via acid-catalyzed dimerization of isobutene or dehydration of tert-butanol. Sulfuric acid (60–98%) or strong acid resins achieve >95% yield under closed conditions .

Optimized Conditions :

• Catalyst: H₂SO₄ (molar ratio 1:0.5 alcohol:acid)

• Temperature: 90–95°C

• Reaction Time: 4–5 hours .

Example Synthesis :

text
350g tert-butanol + 250g 80% H₂SO₄ → 235g TMP1 (94% yield)[3].  

Reaction with Hydroxyl Radicals

In the atmosphere, TMP1 reacts with hydroxyl radicals (- OH) at a rate constant of $8.77\times 10^{-11}\,\text{cm}^3/\text{molecule s}$ . This reaction contributes to its environmental degradation.

Industrial Applications

2,4,4-Trimethyl-1-pentene serves as an essential building block in the production of various chemicals and materials:

• Synthetic Rubber and Plastics : It is widely used in the production of synthetic rubber tackifiers and plasticizers. These additives enhance the performance characteristics of rubber and plastic products by improving flexibility and durability .
• Surfactants : The compound is utilized in the synthesis of surfactants that are crucial for detergents, emulsifiers, and wetting agents. These surfactants help reduce surface tension in liquids, facilitating better mixing and spreading .
• Phenolic Resins : this compound acts as a modifier for phenolic resins, which are used in adhesives, coatings, and molded products due to their excellent thermal stability and mechanical properties .
• Epoxy Resins : It is also employed in the formulation of epoxy resins that are used in coatings and composite materials for their strong adhesive properties and resistance to environmental factors .
• Ultraviolet Absorbers : The compound can be transformed into ultraviolet absorbers that protect materials from degradation caused by UV radiation, thus extending their lifespan .

Environmental Considerations

While this compound has numerous applications, it is also associated with environmental concerns. The compound is highly flammable and poses risks of explosion when mixed with air . Additionally, it is toxic to aquatic organisms and can bioaccumulate in fish . Therefore, proper handling and disposal procedures are critical to mitigate its environmental impact.

Toxicity Studies

Research has been conducted to evaluate the toxicity of this compound:

• A study involving Sprague-Dawley rats indicated that exposure to high doses resulted in increased liver and kidney weights, suggesting potential systemic toxicity at elevated levels .

Case Study 1: Production Efficiency

A recent patent describes a method for producing this compound with high purity and yield using tert-butanol or isobutanol as raw materials. The method involves a closed reaction process that significantly increases yield (up to 95%) compared to traditional methods . This advancement highlights the importance of optimizing production processes to enhance efficiency in industrial applications.

Case Study 2: Environmental Impact Assessment

An environmental assessment was conducted to evaluate the effects of this compound on aquatic ecosystems. The findings indicated a need for stringent regulations on its use due to its toxic effects on marine life. Recommendations included improved waste management practices and the development of safer alternatives in industrial applications .

The mechanism of action of diisobutylene involves its reactivity with various chemical agents. It reacts with strong oxidizing agents to form oxidized products and with reducing agents to release hydrogen gas . The molecular targets and pathways involved in these reactions are primarily related to its alkene structure, which allows it to undergo addition and polymerization reactions .

Structural Isomers: 2,4,4-Trimethyl-2-pentene

TMP is often found as a mixture with its structural isomer 2,4,4-trimethyl-2-pentene (commonly termed di-isobutylene). Key differences include:

The isomer mixture (typically 3:1 ratio of 1-pentene to 2-pentene) is marketed as di-isobutylene, a valuable fuel additive .

Branched Alkenes in the C₇–C₉ Range

TMP belongs to a class of branched alkenes evaluated for fuel applications. Comparisons include:

Key Findings :

• Fuel Performance: TMP-based di-isobutylene outperforms linear alkenes in octane enhancement due to its branched structure, which reduces premature combustion (knocking) .
• Combustion Kinetics : TMP exhibits distinct oxidation pathways compared to iso-octane, with faster radical formation due to its unsaturated structure .

Saturated Analogs: 2,2,3-Trimethylpentane

Compared to saturated hydrocarbons like 2,2,3-trimethylpentane , TMP shows:

Functionalized Derivatives: Methanol-TMP Mixtures

Phase equilibrium studies reveal TMP’s miscibility with alcohols:

• Methanol + TMP: Forms azeotropes at 331 K, impacting distillation processes .

Polymer Chemistry

• TMP’s bulky structure in poly[(maleic anhydride)-alt-TMP] (PMP) segregates polymer chains, reducing intra-chain interactions and photoluminescence efficiency. This contrasts with flexible copolymers like poly[(1-octene)-co-ITA] , which exhibit stronger emissions .

Fuel Additives

• Di-isobutylene (TMP mixture) achieves a RON > 100 , outperforming many linear alkenes. Its high branching improves fuel stability and combustion efficiency .

Table 1: Physical Properties of Selected Compounds

Table 2: Application Comparison

2,4,4-Trimethyl-1-pentene (C8H16) is an organic compound classified as an alkene. It is primarily used in industrial applications, particularly in the production of various chemical intermediates and fuels. Understanding its biological activity is crucial for assessing its environmental impact and potential health effects.

• Molecular Formula : C8H16
• Molecular Weight : 112.21 g/mol
• CAS Number : 107-39-1
• IUPAC Name : 2,4,4-trimethylpent-1-ene

Synthesis and Industrial Use

The synthesis of this compound typically involves the dehydration of tert-butanol or isobutanol using sulfuric acid as a catalyst under controlled conditions. Recent advancements have reported yields exceeding 95% when reactions are conducted in closed systems at elevated temperatures . This efficiency makes it a valuable compound in the production of specialty chemicals and fuels.

Biological Activity Overview

The biological activity of this compound can be categorized into several areas:

1. Toxicological Effects

Studies indicate that this compound can cause irritation to the skin and eyes upon exposure. Ingestion may lead to gastrointestinal irritation . The compound's safety data sheets highlight potential health risks associated with high concentrations.

2. Environmental Impact

As a volatile organic compound (VOC), this compound contributes to air pollution and can participate in photochemical reactions leading to ozone formation. Its presence in gasoline formulations has been noted, where it constitutes approximately 0.011% of industrial average gasoline .

3. Biodegradation Studies

Research has shown that alkenes like this compound can undergo microbial degradation in anaerobic environments. This process is essential for assessing the compound's persistence in the environment and its potential for bioaccumulation.

Case Study 1: Health Effects Assessment

A study conducted on the effects of exposure to various alkenes, including this compound, found that prolonged exposure could lead to respiratory issues and skin sensitization. The study involved occupational exposure assessments among workers in chemical manufacturing settings .

Case Study 2: Environmental Remediation

In a remediation project aimed at reducing VOC levels in groundwater contaminated by industrial activities, this compound was monitored alongside other hydrocarbons. Results indicated that while some compounds were effectively degraded by anaerobic bacteria, the degradation rate of this compound was slower compared to simpler alkenes .

Research Findings

Q. Basic: What are the recommended methods for synthesizing and purifying 2,4,4-trimethyl-1-pentene to achieve high purity for research purposes?

This compound is typically synthesized via acid-catalyzed dimerization of isobutylene, which often produces a mixture of isomers, including 2,4,4-trimethyl-2-pentene . To isolate the 1-pentene isomer, fractional distillation under reduced pressure (e.g., 101°C boiling point at atmospheric pressure) is critical, with careful temperature control to minimize thermal degradation . Gas chromatography (GC) coupled with mass spectrometry (MS) is recommended for purity verification, as spectral libraries (e.g., NIST) provide reference fragmentation patterns for isomer differentiation .

Q. Basic: How do the thermodynamic properties of this compound, such as enthalpy of vaporization and boiling point, influence its handling in laboratory settings?

The compound’s low boiling point (101°C) and high volatility (vapor pressure: 10 kPa at 38°C) necessitate storage in sealed, fireproof containers under inert gas to prevent evaporation and combustion . Its enthalpy of vaporization (ΔvapH° = 7.05 kcal/mol) indicates significant energy input is required for phase changes in distillation processes . Researchers must use explosion-proof equipment and avoid electrostatic discharge due to its low flash point (-5°C) and flammability range (0.8–4.8 vol% in air) .

Q. Advanced: What experimental approaches are used to resolve discrepancies between observed combustion behavior and existing kinetic models for this compound?

Discrepancies in combustion kinetics, such as flame speed and ignition delay, are addressed through shock tube experiments and laminar flame studies paired with detailed kinetic models . For example, Sun et al. (2019) identified deviations in predicted intermediate radical concentrations (e.g., CH3 and C2H5) by comparing laser-induced fluorescence (LIF) measurements with CHEMKIN simulations. Adjustments to rate constants for β-scission and H-abstraction reactions in the model improved alignment with experimental data .

Q. Advanced: How does the presence of isomeric impurities like 2,4,4-trimethyl-2-pentene affect the chemical reactivity and analysis of this compound in catalytic studies?

Isomeric impurities alter reaction pathways, particularly in acid-catalyzed systems. For instance, in hydration studies, the 2-pentene isomer exhibits slower reaction rates due to steric hindrance around the double bond. Nuclear magnetic resonance (NMR) analysis (e.g., 13C NMR) can distinguish isomers via chemical shift differences (e.g., δ 115–125 ppm for olefinic carbons) . Researchers should employ high-resolution GC-MS or HPLC with chiral columns to quantify isomer ratios and assess their impact on kinetic outcomes .

Q. Advanced: What methodologies are recommended for assessing the environmental persistence and bioaccumulation potential of this compound in aquatic ecosystems?

The Japanese MITI biodegradation test (OECD 301C) classifies the compound as slowly biodegradable (no degradation observed in 28 days), suggesting persistence in soil and water . Bioaccumulation potential is estimated using the log Kow (4.55) and regression models (e.g., log BCF = 2.80), indicating moderate-to-high bioconcentration in fish . Microcosm studies with 14C-labeled analogs are recommended for tracking degradation metabolites and partitioning behavior in sediment-water systems.

Q. Basic: What spectroscopic techniques are most effective for identifying and characterizing this compound in complex mixtures?

• IR Spectroscopy : Distinct C=C stretching vibrations at ~1650 cm⁻¹ and methyl group absorptions at 1375–1465 cm⁻¹ .
• Mass Spectrometry : Base peak at m/z 57 ([(CH3)2C=CH]+) and molecular ion at m/z 112 (C8H16+) .
• UV/Vis : Weak absorption at ~190 nm due to π→π* transitions, useful for quantifying low concentrations in hydrocarbon matrices .

Q. Advanced: In fuel additive research, how do the combustion characteristics of this compound compare to iso-octane, and what implications does this have for engine performance?

Compared to iso-octane, this compound exhibits higher laminar flame speeds (e.g., 35–40 cm/s vs. 30 cm/s at φ = 1.0) due to faster radical propagation in lean conditions . However, its lower research octane number (RON) increases knocking propensity in turbocharged engines. Engine tests show elevated aldehyde emissions (e.g., formaldehyde), necessitating catalytic converter optimization for compliance with emissions standards .

Q. Advanced: What are the challenges in reconciling theoretical predictions of thermodynamic properties with experimental data for this compound?

Group contribution methods (e.g., Joback) underestimate enthalpy of vaporization by ~5% compared to experimental values (7.05 kcal/mol vs. 7.36 kcal/mol) due to non-ideal intermolecular interactions in branched alkenes . Discrepancies in heat capacity (Cp) calculations arise from incomplete anharmonic corrections in density functional theory (DFT). Hybrid methods combining experimental data (e.g., NIST TRC tables) with ab initio calculations (e.g., CBS-QB3) improve accuracy for property databases .