Inorganic Gold Compound Synthesis Using Halogen Oxidizers
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Solution Overview
Problem
Conventional methods for producing inorganic gold compounds like tetrachloroauric acid, sodium tetrachloroaurate, and potassium tetrachloroaurate are hazardous, costly, time-consuming, and environmentally harmful due to the use of toxic chemicals such as chlorine gas and hydrogen peroxide, and require prior manufacture of intermediate materials.
Innovation Solution
A method involving the treatment of gold with a halogen-containing oxidizing agent in hydrochloric acid to produce tetrachloroauric acid, sodium tetrachloroaurate, or potassium tetrachloroaurate, using oxidizing agents like oxy-halogen acids, oxy-halogen salts, or halogen oxides, which exclude chlorine gas, allowing for a safer, more efficient, and cost-effective process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If chlorine gas is used as oxidizing agent in hydrochloric acid to produce tetrachloroauric acid, then the production efficiency is improved, but the hazard and environmental pollution increase due to toxic gas handling requirements
Solution Approach 1:
The patent converts the harmful chlorine gas into beneficial chlorine-containing compounds (hypochlorous acid, chlorous acid, chloric acid, perchloric acid, or their salts) that serve as oxidizing agents. This transformation eliminates the need for handling toxic chlorine gas while maintaining the oxidation capability required for efficient gold dissolution and tetrachloroauric acid production.
Solution Approach 2:
The patent introduces intermediary substances (hypochlorous acid, chlorous acid, chloric acid, perchloric acid, or their metal salts) as mediators between the gold and the oxidizing process. These intermediaries facilitate the oxidation of gold to gold(III) without requiring direct contact with chlorine gas, thus reducing toxicity and environmental harm while maintaining production efficiency.
2Productivity
If hydrogen peroxide is used as oxidizing agent in concentrated hydrochloric acid at high temperature, then the production of tetrachloroauric acid is achieved, but the risk of explosion and thermal decomposition increases
Solution Approach 1:
The patent changes the chemical parameters of the oxidizing agent from hydrogen peroxide to chlorine-containing compounds (hypochlorous acid, chlorous acid, chloric acid, perchloric acid, or their salts). These alternative oxidizing agents have different stability characteristics and do not carry the same explosion risk at high temperatures, thereby improving safety while maintaining production capability.
Solution Approach 2:
The patent employs chlorine-containing oxidizing agents that can be generated in situ and decompose harmlessly into water and oxygen, avoiding the need for large quantities of unstable hydrogen peroxide. This approach reduces the risk of thermal decomposition and explosion while achieving the required production levels of tetrachloroauric acid.
3Productivity
If aqua regia is used to dissolve and oxidize gold, then the production of tetrachloroauric acid is achieved, but the generation of toxic nitrogen oxides and environmental pollution occurs
Solution Approach 1:
The patent replaces the harmful nitrogen-containing oxidizing system (aqua regia) with a chlorine-based system that generates no toxic nitrogen oxides. The chlorine-containing oxidizing agents (hypochlorous acid, chlorous acid, chloric acid, perchloric acid, or their salts) oxidize gold efficiently while producing only water and oxygen as byproducts, thereby eliminating nitrogen oxide pollution while maintaining gold dissolution efficiency.
Solution Approach 2:
The patent substitutes the chemical mechanism of aqua regia (which involves nitric acid oxidizing gold and forming nitrogen oxides) with a different chemical mechanism using chlorine-containing compounds. This substitution maintains the oxidation function but eliminates the harmful nitrogen oxide generation, achieving cleaner production with the same productivity.
4Productivity
If conventional methods are used to produce sodium tetrachloroaurate and potassium tetrachloroaurate, then the production is achieved, but the process complexity and time consumption increase due to prior manufacture of intermediate materials
Solution Approach 1:
The patent merges the production of tetrachloroauric acid with the subsequent formation of sodium tetrachloroaurate or potassium tetrachloroaurate into a single integrated process. By adding sodium chloride or potassium chloride to the reaction mixture during the oxidation of gold, the patent eliminates the need for separate steps to produce intermediate tetrachloroauric acid and then convert it to the metal salt, thereby reducing process complexity and time while maintaining production output.
Solution Approach 2:
The patent performs preliminary action by adding the metal chloride (sodium chloride or potassium chloride) to the reaction mixture before the oxidation of gold is complete. This preliminary preparation ensures that the metal salt forms directly during the oxidation process, eliminating subsequent separation and purification steps, thus reducing overall process complexity and time while achieving the required production output.
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 method simplifies the production process, reduces hazards, lowers costs, and enhances environmental safety while achieving high yields of inorganic gold compounds, such as tetrachloroauric acid, sodium tetrachloroaurate, and potassium tetrachloroaurate, with improved efficiency compared to traditional methods.
Implementation Method 1
treating gold with a halogen-containing oxidizing agent in a hydrochloric acid to obtain the inorganic gold compound
Data Source
AI summary
A method of making the inorganic gold compound, such as tetrachloroauric acid, sodium tetrachloroaurate, potassium tetrachloroaurate, sodium tetracyanoaurate, and potassium tetracyanoaurate, includes the step of: treating gold with a halogen-containing oxidizing agent in a hydrochloric acid to obtain the inorganic gold compound, wherein the halogen-containing oxidizing agent excludes chlorine gas. The method of making the inorganic gold compound is simple, safe, time-effective, cost-effective, and environment-friendly, and has the advantage of high yield.