Methyl Limonitrile Synthesis via Segmented Reaction and Isomerization
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Solution Overview
Problem
There is a lack of an efficient and economic process for manufacturing methyl limonitrile, a mixture of 3,7-dimethyl-2,6-nonadiene nitrile, 7-methyl-3-methylene-6-nonene nitrile, and 3,7-dimethyl-3,6-nonadiene nitrile, which are used as a fragrance substitute for geranylnitrile to avoid its toxicological disadvantages, while maintaining similar olfactive properties.
Innovation Solution
A process involving the reaction of 6-methyl-5-octen-2-one with cyano acetic acid in the presence of a base (pyridine) and a co-base (1,4-diamino butane) in an organic solvent (toluene), followed by removal of water and carbon dioxide, distillation, isomerization, extraction with diluted acids, and recycling of unconverted starting materials to achieve the desired isomer ratio and purity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If methyl limonitrile is manufactured to achieve high purity (>98 area-%) and desired isomer ratio, then olfactive quality is improved, but process complexity and manufacturing cost increase
Solution Approach 1:
The manufacturing process is divided into distinct sequential steps: reaction step, water/CO2 removal step, distillation step, and isomerization step. Each step targets a specific aspect of purification or transformation, allowing complex requirements to be met through manageable individual operations rather than a single complex process
Solution Approach 2:
An organic solvent is introduced as an intermediary medium to facilitate the reaction between 6-methyl-5-octen-2-one and cyano acetic acid. The solvent enables the reaction to proceed efficiently and allows for subsequent separation and purification steps, achieving high purity without requiring overly complex direct synthesis methods
2Manufacturing precision
If methyl limonitrile is manufactured to achieve high purity (>98 area-%) and desired isomer ratio, then olfactive quality is improved, but manufacturing cost increases
Solution Approach 1:
The reaction system is designed to self-regulate and self-purify through the sequential steps. The water and carbon dioxide removal step eliminates byproducts automatically, and the isomerization step automatically adjusts the isomer ratio to the desired range, reducing the need for additional expensive purification operations and manual interventions
Solution Approach 2:
The process utilizes controlled changes in physical parameters (temperature, pressure) during distillation and isomerization steps to selectively separate and transform compounds. By optimizing these parameters, high purity and specific isomer ratios are achieved through efficient physical separation rather than expensive chemical purification methods
3Manufacturing precision
If water and carbon dioxide are removed during the reaction, then product purity is improved, but process time and energy consumption increase
Solution Approach 1:
The water and carbon dioxide removal is performed continuously during the reaction process rather than as a separate batch operation. This continuous removal maintains driving force for the reaction and achieves purification without interrupting the overall process flow, minimizing total process time while ensuring high 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
This process achieves a high-purity, olfactive-quality methyl limonitrile with a desired isomer ratio, suitable for use as a fragrance and flavor, with a purity of >98 area-%, addressing the inefficiencies and economic constraints of existing methods.
Implementation Method 1
reacting 6-methyl-5-octen-2-one with cyano acetic acid and removing water and carbon dioxide, wherein the reaction and the removal of water and carbon dioxide are performed in the presence of a base and a co-base
Implementation Method 2
in an organic solvent as shown in FIG. 1
Implementation Method 3
removal of water and carbon dioxide
Implementation Method 4
followed by removal of water and carbon dioxide, distillation, isomerization
Data Source
AI summary
The present invention is directed to a process for the manufacture of methyl limonitrile comprising a mixture of 3,7-dimethyl-2,6-nonadiene nitrile, 3,7-dimethyl-3,6-nonadiene nitrile and 7-methyl-3-methylene-6-nonene nitrile comprising the following steps: a) reacting 6-methyl-5-octen-2-one with cyano acetic acid and removing carbon dioxide and water, wherein the reaction and the removal of carbon dioxide and water are performed in the presence of a base and a co-base in an organic solvent, wherein the base is pyridine, wherein the co-base is 1,4-diamino butane, and wherein the organic solvent is a solvent which forms a heteroazeotrop with water; b) removing the solvent and pyridine of the reaction mixture obtained after having performed step a) or step c) by distillation to obtain a reaction mixture; c) isomerizing the reaction mixture obtained after having performed step a) or step b) to obtain an isomerized reaction mixture; whereby step b) can be performed before or after step c).