Nickel Catalyst Hydrogenation of Limonene-4-ol
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for hydrogenating limonene-4-ol to terpinene-4-ol require high-pressure reactors and result in low yields and purity due to the generation of by-products, and existing synthetic routes are costly and complex for industrial scale-up.
Innovation Solution
A process using a nickel catalyst in the presence of carboxylic acid esters as solvents, such as ethyl acetate, for the hydrogenation of limonene-4-ol, allowing for high purity and yield of terpinene-4-ol without the need for extensive purification of limonene-4-ol or replacement of solvents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high hydrogen pressure is used to obtain primarily terpinene-4-ol, then the yield and purity of terpinene-4-ol is improved, but expensive high-pressure reactors are required and safety requirements increase
Solution Approach 1:
The patent changes the chemical parameters of the reaction system by introducing a specific catalyst system (nickel catalyst combined with acid catalyst) and using carboxylic acid esters as solvent. This parameter change allows the hydrogenation to proceed effectively at low hydrogen pressure while maintaining high selectivity for terpinene-4-ol, thereby resolving the contradiction between purity and reactor complexity
Solution Approach 2:
The patent uses carboxylic acid esters as an intermediary solvent that facilitates the hydrogenation reaction. The ester solvent interacts with the catalyst and reactants to promote selective hydrogenation at low pressure, acting as a mediator that enables the reaction to proceed under milder conditions while achieving high purity product
2Productivity
If high hydrogen pressure is used to obtain primarily terpinene-4-ol, then the yield and purity of terpinene-4-ol is improved, but the reaction generates relatively high amounts of by-products which reduce yield and purity
Solution Approach 1:
The patent employs a dual-catalyst system (nickel catalyst plus acid catalyst) and uses carboxylic acid esters as solvent, creating a specific reaction environment that enhances selectivity. This parameter change modifies the reaction pathway to favor terpinene-4-ol formation while minimizing by-product generation, thereby improving yield without the harmful effects associated with high-pressure reactions
Solution Approach 2:
The patent uses a composite catalyst system combining nickel catalyst with acid catalyst (such as p-toluenesulfonic acid or ammonium formate). This composite catalytic system works synergistically to promote the hydrogenation reaction with high selectivity, enabling high productivity while reducing by-product formation through the combined effects of the two catalysts
3Productivity
If pure limonene-4-ol is used as starting material, then the reaction efficiency is improved, but tedious distillation procedures are required to separate limonene-4-ol from the previous synthesis step
Solution Approach 1:
The patent employs carboxylic acid esters as solvent that can be directly used from the previous synthesis step without replacement. The ester solvent system allows the reaction to proceed effectively with limonene-4-ol obtained directly from the epoxide opening reaction, eliminating the need for separate purification steps. The system essentially serves itself by carrying over the solvent and product from one step to the next
Solution Approach 2:
The carboxylic acid ester solvent performs multiple functions: it serves as the reaction medium for the epoxide opening step, carries the limonene-4-ol product through without requiring separation, and provides the optimal environment for the subsequent hydrogenation reaction. This multi-functionality eliminates intermediate purification steps and improves overall process efficiency
4Ease of operation
If conventional solvents are used for nickel-catalyzed hydrogenation, then the reaction can proceed, but the solvent undergoes hydrolysis under the reaction conditions
Solution Approach 1:
The patent changes the solvent parameter from conventional water-miscible solvents (like ethanol) to carboxylic acid esters (such as ethyl acetate, n-propyl acetate, or n-butyl acetate). This parameter change selects a solvent that is inherently more stable under nickel-catalyzed hydrogenation conditions, preventing hydrolysis while maintaining good reaction feasibility and product solubility
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
This method achieves high purity and yield of terpinene-4-ol with reduced by-products and operational complexity, suitable for industrial scale, using readily available nickel catalysts and carboxylic acid esters as solvents.
Implementation Method 1
contacting limonene-4-ol of formula (I) with hydrogen in the presence of at least one nickel catalyst
Implementation Method 2
hydrogenation reaction in the presence of a nickel catalyst
Data Source
AI summary
The present invention relates to a process for preparing terpinene-4-ol from limonene-4-ol via a hydrogenation reaction in the presence of a nickel catalyst.