Pyridazinone Herbicide Synthesis Through Grignard Intermediates

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Solution Overview

Problem

There is a need for improved herbicidal pyridazinones and methods of preparing them, as existing technologies are inadequate.

Innovation Solution

The development of pyridazinones and processes for preparing pyridazinones, including reacting compounds of Formula II with magnesium to form intermediates, and further reacting these intermediates with other compounds to introduce various substituents, such as alkyl, cycloalkyl, halogen, and methoxy groups, to create compounds of Formula I and their N-oxides or salts, which can be used as herbicides.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If existing pyridazinone preparation methods are used, then the process is simpler, but the herbicidal properties are insufficient

Engineering Contradiction:

Improveherbicidal propertiesVSAvoidpreparation process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The preparation process is divided into multiple discrete steps: Step 1 forms a Grignard reagent from a halogenated pyridazinone and magnesium, Step 2 reacts the Grignard reagent with carbon dioxide to form a carboxylic acid, and Step 3 converts the carboxylic acid to the final pyridazinone herbicide. This segmentation allows each step to be optimized independently for both yield and herbicidal activity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary formation of the Grignard reagent under controlled conditions (anhydrous environment, specific temperature range) before introducing the electrophilic substrate. This preliminary action ensures the nucleophile is fully activated and stable before the coupling reaction, improving overall process reliability and herbicidal property consistency.

Inventive Principle:

Principle #10Preliminary action

2Productivity

If existing pyridazinone compounds are used, then the synthesis is faster, but the range of herbicidally active compounds is limited

Engineering Contradiction:

Improvesynthesis speedVSAvoidrange of herbicidally active compounds

Core Design Contradiction:

ProductivityVSAdaptability or versatility

Solution Approach 1:

The patent employs a universal Grignard reaction platform that can accommodate various halogenated pyridazinone substrates (chloro, bromo, iodo) and various electrophilic reagents (carbon dioxide, alkyl halides, aryl halides). This multi-functional approach enables rapid generation of diverse pyridazinone compounds with different substituent patterns, expanding the range of herbicidally active compounds while maintaining efficient synthesis through a common reaction mechanism.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent systematically varies key reaction parameters including the halogen type (Cl, Br, I), the electrophile structure (alkyl, aryl, heteroaryl), and reaction conditions (temperature, solvent, stoichiometry) to generate a library of pyridazinone derivatives. This parameter optimization enables discovery of compounds with enhanced herbicidal activity while maintaining practical synthesis speeds through identified optimal conditions.

Inventive Principle:

Principle #35Parameter changes

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 processes provide improved pyridazinones with enhanced herbicidal properties, offering a range of compounds suitable for agricultural use.