[1,4,5]-Oxadiazepine Derivative Synthesis Without Thermally Unstable DMSO
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing commercial process for preparing pinoxaden, a graminicidal herbicide, faces issues such as thermal decomposition of dimethyl sulphoxide (DMSO), low isolated yields, poor volume yields, high waste streams, and process complexity due to the need for multiple distillation steps and different solvents.
Innovation Solution
A novel process involving the reaction of R1—C(O)—NH—NH—C(O)—R2 with R3—CH2—CH2—O—CH2—R4 in the presence of an alcoholic solvent, using a phase-transfer catalyst and a base, which eliminates the use of DMSO, reduces solvent swaps, and optimizes reaction conditions to enhance yield and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If DMSO is used as solvent in the reaction of diacetylhydrazine and dichloroethyl ether, then the reaction can proceed, but thermal decomposition occurs leading to safety hazards and low isolated yields
Solution Approach 1:
The patent changes the solvent parameter from DMSO to alternative solvents (ethanol, methanol, isopropanol, acetonitrile, or water) that do not undergo thermal decomposition at reaction temperatures, thereby eliminating safety hazards while maintaining reaction efficiency and improving isolated yields
Solution Approach 2:
The patent extracts and removes DMSO from the reaction system entirely, replacing it with safer alternative solvents that do not pose thermal decomposition risks, thereby eliminating the harmful effect while preserving the essential reaction function
2Ease of manufacture
If DMSO and DCEE are combined for the reaction, then the reaction can be performed, but high toxicity is generated
Solution Approach 1:
The patent removes DMSO from the reaction system and replaces it with less toxic alternative solvents, thereby eliminating the harmful toxic effect of the DMSO/DCEE combination while maintaining reaction feasibility through the alternative solvent system
Solution Approach 2:
The patent substitutes expensive and toxic DMSO with cheaper, less toxic alternative solvents that can be easily disposed of or recycled, reducing environmental and safety concerns while maintaining process effectiveness
3Manufacturing precision
If multiple distillation steps and different solvents are used for reaction and crystallisation, then purification can be achieved, but process complexity and cost increase
Solution Approach 1:
The patent merges the reaction solvent and crystallisation solvent into a single solvent system, eliminating the need for solvent swaps and reducing process complexity. The same solvent used for reaction is also used for product crystallisation and purification
Solution Approach 2:
The patent makes the solvent system universal by selecting a solvent that serves multiple functions: reaction medium, purification agent, and crystallisation solvent. This multi-functional approach simplifies the overall process while maintaining purification quality
4Productivity
If DMSO is used at high concentration to improve reaction rate, then productivity increases, but thermal decomposition risk increases
Solution Approach 1:
The patent changes the solvent parameter from thermally unstable DMSO to thermally stable alternatives, allowing the reaction to proceed at high concentrations and temperatures without thermal decomposition, thereby simultaneously achieving high productivity and reliability
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 new process achieves safer operation with higher process concentrations, reduces waste, and lowers costs by eliminating toxic solvent combinations, while improving yield and efficiency through optimized solvent use and reaction control.
Implementation Method 1
The reaction of R1—C(O)—NH—NH—C(O)—R2 with R3—CH2—CH2—O—CH2—R4 in the presence of an alcoholic solvent, using a phase-transfer catalyst and a base
Data Source
AI summary
A process for the preparation of a compound of formula (I):comprising the reaction of:R1—C(O)—NH—NH—C(O)—R2, with R3—CH2—CH2—O—CH2—CH2—R4,in the presence of an alcoholic solvent;wherein R1 and R2 are independently selected from straight or branched chain alkyl groups, or are bonded to form a 4, 5, or 6-membered heterocycle, andwherein R3 and R4 are independently selected from a halide or a sulphate.