Layer Melt Crystallization of Monoterpenes with Oxygen-Containing Solvent

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Solution Overview

Problem

Current methods for purifying monoterpene compounds, such as menthol and isopulegol, through crystallization lack sufficient stereoisomeric separation efficiency and yield, requiring costly and energy-intensive processes with limited plant capacity.

Innovation Solution

A layer melt crystallization process is employed with an oxygen-containing solvent (20 ppm to 2% by weight) like water or methanol, which enhances stereoisomeric separation and crystallization efficiency, favoring the formation of metastable phases that improve yield and purity of specific stereoisomers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional crystallization methods are used to purify monoterpene compounds, then purification is achieved, but stereoisomeric separation efficiency is insufficient and yield is limited

Engineering Contradiction:

Improvestereoisomeric separation efficiencyVSAvoidpurification yield

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The patent applies parameter changes by carefully controlling crystallization temperature, cooling rate, and solvent composition to optimize the separation of stereoisomers. By adjusting these parameters, the process achieves both high stereoisomeric separation efficiency and high yield of purified monoterpene compounds

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention utilizes phase transitions during melt crystallization, where the crude monoterpene composition transitions from liquid to solid phase. This phase change enables selective crystallization of desired stereoisomers while impurities remain in the melt, simultaneously improving separation efficiency and yield

Inventive Principle:

Principle #36Phase transitions

2Manufacturing precision

If conventional crystallization processes are used, then purification is achieved, but the process is costly and energy-intensive

Engineering Contradiction:

Improvestereoisomeric purityVSAvoidenergy consumption

Core Design Contradiction:

Manufacturing precisionVSUse of energy by stationary object

Solution Approach 1:

The process employs self-service by utilizing the inherent crystallization properties of monoterpene compounds and the heat released during crystallization itself. The exothermic crystallization provides part of the cooling energy needed, reducing external energy input while maintaining high stereoisomeric purity

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent uses simple, inexpensive equipment for melt crystallization rather than complex, expensive purification systems. The process requires basic crystallization vessels and temperature control, avoiding costly specialized equipment while achieving high purification standards

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Manufacturing precision

If conventional crystallization methods are applied, then purification is achieved, but plant capacity is limited

Engineering Contradiction:

Improvestereoisomeric purityVSAvoidplant capacity

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The patent applies segmentation by dividing the crystallization process into multiple stages with different cooling rates and temperature profiles. This staged approach increases overall plant capacity by allowing continuous operation and better utilization of equipment while maintaining high stereoisomeric purity in each stage

Inventive Principle:

Principle #1Segmentation

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 process achieves high yield and stereoisomeric purity of target monoterpene compounds, is cost-efficient, energy-efficient, and requires smaller plants, while effectively separating and purifying specific stereoisomers like L-(-)-isopulegol and D-(-)-isopulegol.

Implementation Method 1

Methodology Applied

Scientific EffectCrystallization: Crystallisation

Implementation Method 2

favoring the formation of metastable phases that improve yield and purity of specific stereoisomers

Methodology Applied

Scientific EffectMetastable phase formation: Metastability

Implementation Method 3

by layer melt crystallization

Methodology Applied

Scientific EffectPhase change: Phase Change

Implementation Method 4

A layer melt crystallization process is employed

Methodology Applied

Scientific EffectTemperature gradient: Temperature Gradient

Data Source

PatentUS10745332B2Process for purifying a crude composition including a monoterpene compound, such as a monocyclic monoterpene alcohol, by layer melt crystallization

Publication Date: 2020.08.18 SULZER MANAGEMENT AG

AI summary

A process for purifying a crude composition includes a monoterpene compound selected from the group consisting of monocyclic monoterpene alcohols, monocyclic monoterpene ketones, bicyclic epoxy monoterpenes and mixtures of two or more of the aforementioned compounds, such as preferably a monocyclic monoterpene alcohol. The process comprises performing a layer crystallization with a melt of the crude composition, and the melt of the crude composition subjected to the layer crystallization includes oxygen-containing solvent in a concentration of 20 ppm to 2% by weight. The oxygen-containing solvent is selected from the group consisting of water, C1-6-alcohols, C1-6-carboxylic acids, C1-6-ketones, C1-6-aldehydes, C1-12-ethers, C1-12-esters and mixtures of two or more of the aforementioned solvents.