Diol Purity via Hydroxypivalaldehyde Crystallization
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Solution Overview
Problem
Conventional methods for producing spiroglycol and diols with cyclic acetal skeletons result in low purity products due to accumulation of impurities, leading to reduced optical and impact resistance properties, increased purification costs, and inefficient use of reaction mother liquor, which complicates industrial production.
Innovation Solution
A method involving an acetalization reaction with controlled impurities in hydroxypivalaldehyde, such as formaldehyde, neopentyl glycol, and isobutyraldehyde, under specific conditions to minimize by-products and reuse reaction mother liquor, ensuring high purity diols like spiroglycol and dioxane glycol are produced.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional acetalization reaction methods are used with standard purity hydroxypivalaldehyde, then production cost is reduced, but the resulting diol has low purity and poor optical properties
Solution Approach 1:
The patent applies preliminary action by pre-purifying hydroxypivalaldehyde through controlled crystallization before the acetalization reaction. The process includes cooling the aqueous solution to 0-5°C to crystallize hydroxypivalaldehyde, filtering to remove mother liquor containing impurities, and then using this purified material in subsequent acetalization reactions. This preliminary purification step ensures high purity diol production without requiring complex post-reaction purification.
2Productivity
If reaction mother liquor is reused without purification, then productivity is improved, but impurity accumulates and diol purity deteriorates
Solution Approach 1:
The patent applies discarding and recovering by systematically separating and removing impurities from reaction mother liquor through controlled crystallization. The mother liquor is cooled to 0-5°C where hydroxypivalaldehyde crystallizes, allowing the impure mother liquor to be filtered off and discarded. This recovery of pure crystallized material while discarding impure mother liquor maintains high purity in subsequent production cycles without requiring complete purification of each batch.
Solution Approach 2:
The patent applies parameter changes by controlling the temperature of the reaction mother liquor to 0-5°C during the crystallization step. This temperature parameter change causes hydroxypivalaldehyde to crystallize while impurities remain in solution, enabling selective separation. The temperature control is critical for achieving the desired purity while maintaining productivity.
3Ease of manufacture
If hydroxypivalaldehyde is not pre-purified, then ease of manufacture is improved, but optical properties and impact resistance of the resulting polymer are reduced
Solution Approach 1:
The patent applies preliminary action by implementing a pre-purification step for hydroxypivalaldehyde before acetalization. The aqueous solution of hydroxypivalaldehyde is cooled to 0-5°C to induce crystallization, then filtered to remove the crystallized material and discard the impure mother liquor. This preliminary purification ensures that the starting material has sufficient purity to produce diols with excellent optical properties and impact resistance, while keeping the overall process relatively simple.
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 approach achieves high purity diols with improved optical and impact resistance properties, reducing production costs and efficiently utilizing reaction mother liquor, thus addressing the limitations of existing methods.
Implementation Method 1
an acetalization reaction step of subjecting raw material hydroxypivalaldehyde and at least pentaerythritol and/or trimethylolpropane to an acetalization reaction under an acid catalyst to obtain a diol having a cyclic acetal skeleton
Implementation Method 2
the reaction solution is solid-liquid separated into a solid of the diol having the cyclic acetal skeleton and a reaction mother liquor
Data Source
Figure 1~2
AI summary
The present invention provides a method for producing a diol having a cyclic acetal skeleton, in which the method include an acetalization reaction step of obtaining a diol having a cyclic acetal skeleton by subjecting raw material hydroxypivalaldehyde and at least pentaerythritol and/or trimethylolpropane to an acetalization reaction under an acid catalyst and the raw material hydroxypivalaldehyde can contain a prescribed amount of at least one impurity selected from the group consisting of formaldehyde, neopentyl glycol, an ester compound having a neopentyl glycol skeleton represented by formula (III), and isobutyraldehyde.