Norbornane Dimethanol Hydrogenation Solvent Selection for Cleaner Yield
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Solution Overview
Problem
Existing methods for producing dimethanol compounds with a norbornane skeleton face challenges in suppressing the production of intermediates and by-products during hydrogenation reactions, leading to low yields and high separation costs due to high viscosity and boiling points, as well as transesterification reactions.
Innovation Solution
A production method using linear or branched secondary or tertiary alcohols as solvents in the hydrogenation reaction, with specific catalyst activation and pressure conditions, to minimize the formation of intermediates and by-products.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If toluene solvent is used in hydrogenation reaction, then the reaction can proceed at high temperature and pressure, but the dimethanol compound precipitates as a paste-like product and requires large amounts of additional methanol for dilution and filtration
Solution Approach 1:
The patent changes the solvent parameter from toluene to a mixed solvent system comprising cyclohexanol and a secondary alcohol (such as 2-butanol, 2-pentanol, or 2-hexanol). This parameter change prevents precipitation of the dimethanol compound while maintaining high-temperature reaction conditions, thereby facilitating easier separation and filtration without requiring large amounts of additional dilution solvent.
2Stability of the object's composition
If methanol or ethanol is used as solvent to prevent paste-like precipitation, then precipitation is avoided, but the partial pressure of these solvents at high temperature lowers hydrogen gas concentration and extends reaction time
Solution Approach 1:
The patent selects secondary alcohols with specific carbon chain lengths (2-butanol, 2-pentanol, or 2-hexanol) as components of the mixed solvent system. These solvents have appropriate volatility characteristics that prevent paste-like precipitation while maintaining sufficient hydrogen gas concentration at high reaction temperatures, thereby avoiding excessive reaction time extension.
3Stability of the object's composition
If cyclohexanol is used as solvent to avoid paste-like product, then precipitation is prevented, but transesterification reaction occurs producing by-products that are difficult to separate
Solution Approach 1:
The patent employs a mixed solvent system where cyclohexanol is combined with a secondary alcohol (2-butanol, 2-pentanol, or 2-hexanol) in specific proportions. This composite solvent parameter reduces the transesterification reaction activity compared to using pure cyclohexanol, thereby suppressing by-product formation while maintaining the solubility benefits of cyclohexanol.
Solution Approach 2:
The secondary alcohol component acts as an intermediary substance that modifies the chemical environment of the solvent system. It reduces the reactivity between cyclohexanol and the ester compound, thereby suppressing transesterification reactions while maintaining the desired solubility properties for preventing paste-like precipitation.
4Manufacturing precision
If distillation purification with many stages is used to separate intermediate from target compound, then separation is achieved, but yield is compromised and the method is not economical
Solution Approach 1:
The patent applies preliminary anti-action by using the optimized mixed solvent system to suppress the formation of intermediate ester compounds during the hydrogenation reaction itself. By preventing intermediate formation at the source through appropriate solvent selection, the need for extensive multi-stage distillation purification is eliminated, thereby maintaining high yield and economic efficiency while achieving the required product purity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method effectively reduces the content of intermediates and by-products to 0.5% or less, improving the yield and ease of separation, making it economically viable for further processing.
Implementation Method 1
a step (A) of subjecting a mixed liquid comprising a starting compound represented by the following formula (2) and a solvent to a hydrogenation reduction in a presence of a catalyst having hydrogenation ability
Implementation Method 2
The catalyst may be activated by being subjected to a reduction reaction in a presence of a reducing gas
Data Source
AI summary
A production method for producing a target compound represented by the following formula (1), the production method including: a step (A) of subjecting a mixed liquid containing a starting compound represented by the following formula (2) and a solvent to a hydrogenation reduction in the presence of a catalyst having hydrogenation ability, wherein the solvent is a linear or branched secondary alcohol or tertiary alcohol: wherein R represents H, CH3, or C2H5, wherein R represents H, CH3, or C2H5, and R1 represents CH3, C2H5, C3H7, or C4H9.