1-Chloro-1-methylcyclopentane

Chemical Properties and Characteristics

• Molecular Weight : 118.6 g/mol
• Appearance : Pale yellow liquid
• Purity : 95%
• Solubility : Soluble in most organic solvents such as pentane, chloroform, and dichloromethane

Applications in Organic Synthesis

1-Chloro-1-methylcyclopentane serves as a versatile building block in organic synthesis. It is particularly useful for creating complex molecules through various reactions, including:

• Formation of Quaternary Centers : Recent studies highlight its role in the Al(III)-promoted formation of all-carbon quaternary centers from aliphatic tertiary chlorides and alkynyl silanes. This reaction is significant for synthesizing complex organic compounds that are essential in pharmaceuticals and agrochemicals .
• Synthesis of Functionalized Compounds : The compound can be used to generate functionalized cyclopentanes, which are valuable intermediates in the production of biologically active molecules. Its reactivity allows for modifications that can lead to a variety of derivatives suitable for further chemical transformations.

Applications in Materials Science

In materials science, this compound is being explored for its potential in developing new materials with desirable properties:

• Polymer Synthesis : The compound is investigated as a monomer or co-monomer in polymerization processes. Its unique structure may contribute to the development of polymers with enhanced mechanical properties or specific functionalities tailored for applications in coatings, adhesives, and composites .
• Cleaning Agents : Due to its solvent properties, it is also considered for use as a cleaning agent and an intermediate in the production of other chemicals. Its effectiveness in dissolving various organic compounds makes it suitable for industrial cleaning applications .

Case Study 1: Formation of Quaternary Centers

A detailed study published in the Journal of Organic Chemistry examined the use of this compound in forming quaternary carbon centers. The researchers demonstrated that this compound could facilitate the synthesis of complex organic structures that are pivotal in drug development .

Case Study 2: Polymer Development

Research conducted on the incorporation of this compound into polymer matrices showed promising results regarding the thermal stability and mechanical strength of the resulting materials. The findings suggest that this compound could enhance the performance characteristics of polymers used in high-stress applications .

Table 1: Comparison of Reaction Conditions

Basic Research Questions

Q. What are the key thermodynamic properties of 1-chloro-1-methylcyclopentane, and how do they inform experimental design?

The enthalpy of vaporization (ΔvapH) and heat capacity (Cp) are critical for designing storage and reaction conditions. Reported ΔvapH values include 39.7 ± 0.1 kJ/mol at 297 K (calorimetry) and 42.1 ± 0.1 kJ/mol at 251–263 K (static method) . Heat capacity data is tabulated across temperature ranges in experimental studies . These properties highlight its volatility, necessitating sealed systems for high-temperature reactions.

Q. Which spectroscopic methods are recommended for structural confirmation of this compound?

While direct evidence is limited, standard organochlorine characterization applies:

• ¹H/¹³C NMR : Identify methyl (δ ~1.5–1.8 ppm) and cyclopentane ring protons (δ ~1.4–2.2 ppm).
• IR Spectroscopy : C-Cl stretching (~550–750 cm⁻¹) and C-H bending in the cyclopentane ring.
• Mass Spectrometry : Molecular ion peak at m/z 120.6 (C₆H₁₁Cl) with fragmentation patterns confirming the chloroalkane structure.

Advanced Research Questions

Q. How can researchers resolve discrepancies in reported vaporization enthalpies for this compound?

Discrepancies (e.g., 39.7 vs. 42.1 kJ/mol) arise from experimental conditions:

• Purity : Impurities (e.g., residual solvents) alter measurements. Use chromatography (GC/HPLC) for sample validation .
• Temperature Range : ΔvapH varies with temperature; compare isothermal vs. dynamic calorimetry methods .
• Instrument Calibration : Standardize against reference compounds (e.g., n-alkanes) to minimize systematic errors .

Q. What strategies mitigate thermal degradation during prolonged reactions involving this compound?

• Temperature Control : Maintain reactions below 263 K (where ΔvapH = 42.1 kJ/mol) to reduce volatility .
• Inert Atmospheres : Use nitrogen/argon to prevent oxidative side reactions.
• Stabilizers : Add radical inhibitors (e.g., BHT) to suppress decomposition pathways common in chlorinated alkanes .

Q. How do computational models predict the reactivity of this compound in nucleophilic substitution (SN) reactions?

• DFT Calculations : Optimize transition states for SN2 mechanisms (e.g., backside attack at the chlorine-bearing carbon).
• Solvent Effects : Simulate polar aprotic solvents (e.g., DMSO) to enhance nucleophilicity .
• Steric Hindrance : The methyl group adjacent to Cl reduces SN2 feasibility, favoring elimination (E2) under basic conditions .

Q. Methodological Notes

• Literature Search : Use validated chemical terms (e.g., CAS 6196-85-6) and synonyms from EPA ChemView and ECHA databases to ensure comprehensive retrieval .
• Safety Protocols : Follow guidelines for chlorinated hydrocarbons: use fume hoods, avoid skin contact, and store in flame-proof cabinets .

Comparison with Structurally Similar Compounds

Structural Analogs and Thermodynamic Properties

The table below compares 1-chloro-1-methylcyclopentane with structurally related chlorinated cycloalkanes and aliphatic compounds:

Key Observations :

• Boiling Points : this compound has a lower boiling point than its cyclohexane counterpart, likely due to reduced ring strain in the cyclohexane system .
• Vaporization Enthalpies: The ΔHvap of this compound (39.7 kJ/mol) is comparable to diethylacetyl chloride (39.4 kJ/mol) but lower than 1-methylcyclopentanol (42.9 kJ/mol), reflecting differences in hydrogen bonding and molecular polarity .

A. Nucleophilic Substitution

This compound undergoes monomolecular heterolysis, with reaction rates influenced by solvent polarity. For example, solvolysis in aqueous NaOH yields 1-methylcyclopentanol, while deuterotributylstannane produces deuterated derivatives with 70% efficiency . By-products like deuterobutane (3.5%) arise from carbon-tin bond cleavage .

In contrast, 1-chloro-1-methylcyclohexane shows slower heterolysis due to steric hindrance from the larger cyclohexane ring, as observed in ion-exchange experiments .

B. Addition Reactions

The synthesis of this compound via HCl addition to 1-methylcyclopentene follows Markovnikov’s rule, with H adding to the less substituted carbon . This contrasts with aliphatic alkenes (e.g., propene), where steric effects dominate regioselectivity .

Thermodynamic Stability and Computational Modeling

Studies using group-contribution methods and quantum calculations reveal:

• Heat Capacity (Cp) : Experimental Cp values for the liquid phase are consistent with predictions for chlorinated cycloalkanes .
• Strain Energy : Cyclopentane derivatives exhibit higher strain than cyclohexanes, impacting thermal stability and reaction pathways .