Aliphatic Ketone Solvent Phenol Synthesis
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for producing phenols from aromatic amines through diazotization and cooking in sulfuric acid solutions result in low purity and unsatisfactory yield, despite attempts to improve selectivity and yield using various solvents.
Innovation Solution
The process involves using aliphatic ketones as solvents in diazo cooking, specifically heating aryldiazonium salts formed from aromatic primary amines in a mixture of hot water and mineral acid, which significantly increases selectivity and yield without the use of copper salts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If heating diazonium salt in sulfuric acid solution at 80-100°C, then the cooking process is simple, but the product purity is low
Solution Approach 1:
The patent introduces an organic solvent as an intermediary substance in the cooking process. The solvent mediates between the diazonium salt and water, creating a three-component system that improves phenol purity while maintaining process simplicity. This resolves the contradiction by adding a facilitating substance rather than complicating the process steps.
Solution Approach 2:
The patent changes the compositional parameters of the cooking system by introducing organic solvents with specific properties (immiscibility with water, appropriate boiling points). This parameter change transforms the simple acid-water system into a optimized three-component system that achieves high purity without increasing process complexity.
2Manufacturing precision
If using complex steam distillation to remove phenol, then selectivity and yield improve, but process complexity increases
Solution Approach 1:
The organic solvent acts as a mediator that facilitates phenol separation through simple decantation rather than complex steam distillation. The solvent's immiscibility with water creates distinct phases, allowing easy separation and achieving high selectivity and yield without complex equipment or multi-step procedures.
Solution Approach 2:
The patent extracts phenol into the organic solvent phase during the cooking process itself, rather than requiring a separate removal step. This extraction occurs in-situ, and the phenol-enriched organic phase can be easily separated by decantation, achieving high selectivity while simplifying the overall process.
3Manufacturing precision
If using solvents like xylene or chlorobenzene, then phenol can be dissolved, but yield remains unsatisfactory
Solution Approach 1:
The patent optimizes solvent parameters by selecting aliphatic ketones with specific boiling points and immiscibility characteristics. These parameter changes result in both good phenol solubility during cooking and easy separability afterward, achieving high yield that was not attainable with xylene or chlorobenzene.
Solution Approach 2:
The patent creates a composite cooking system combining mineral acid, water, and organic solvent in specific proportions. This composite system provides synergistic effects where the solvent enhances phenol formation and separation simultaneously, achieving high yield that neither component could achieve alone.
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 a high selectivity and yield of phenols, surpassing previous methods that used solvents like xylene, chlorobenzene, or toluene, with preferred ketones such as methyl isobutyl ketone demonstrating exceptional performance.
Implementation Method 1
an aryldiazonium salt, which is obtained by diazotization of a corresponding aromatic, primary amine
Implementation Method 2
is prepared by heating in a mixture containing hot water and a mineral acid and an organic solvent to form phenol
Implementation Method 3
These ketones are essentially poorly miscible with an aqueous medium in which a corresponding diazo compound undergoes decomposition
Implementation Method 4
is prepared by heating in a mixture containing hot water and a mineral acid and an organic solvent
Data Source
AI summary
The present invention relates to a process for the preparation of phenols in which an aryldiazonium salt, which is prepared by the diazotization of a corresponding aromatic, primary amine, by heating in a mixture comprising hot water, a mineral acid and an organic solvent, is decomposed, where the organic solvent comprises a ketone of the formula (I) R1C(O)R2, in which R1 and R2, independently of one another, are (C1-C5)-alkyl and R1 and R2 together have at least four carbon atoms, where the aromatic primary amine is aniline or a substituted aniline which comprises at least one further substituent which is selected from: alkyl, alkenyl, alkynyl, halogen, haloalkyl, cycloalkyl, heteroalkyl, carboxyl, cyano, alkoxy and ester, and where essentially no copper salts are present in the mixture.