1-hexyl-1H-pyrazole-4,5-diamine hemisulfate for stable oxidative hair dyeing
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Solution Overview
Problem
Oxidative hair dye precursors are unstable and degrade over time, especially when exposed to light and humidity, leading to the formation of oxidized derivatives and dimers, which affects their stability and performance during storage and use in hair dyeing processes.
Innovation Solution
The development of 1-hexyl-1H-pyrazole-4,5-diamine hemisulfate, a novel primary intermediate that combines stability during storage with excellent color intensity and shade performance, is used in compositions for oxidative hair dyeing, along with a coupler and an oxidizing agent, forming a kit that includes a tint component and a developer component.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If amino groups are present in hair coloring precursors to enable oxidative hair dyeing chemistry, then the dyeing performance is improved, but the stability of the precursors deteriorates and they degrade over time forming oxidized derivatives and dimers
Solution Approach 1:
The precursor molecule is divided into two separate components: a stable amino-containing fragment and an oxidizable fragment. These components are stored separately and only combined at the time of use through oxidation, preventing premature degradation while maintaining dyeing effectiveness.
Solution Approach 2:
The amino groups are pre-installed on the precursor structure in a protected or stable form before the oxidation step. This preliminary preparation allows the molecule to remain stable during storage while being ready for the dyeing reaction when activated.
2Loss of time
If hair coloring precursors are stored for long periods during manufacturing, packing, transportation and storage, then the product availability is improved, but the degradation of precursors increases forming oxidized derivatives and dimers
Solution Approach 1:
The precursor is segmented into stable storage form and active dyeing form, allowing long-term storage of the stable component without degradation, then activating it immediately before use.
Solution Approach 2:
The chemical state of the precursor is changed from an oxidized/unstable form during storage to an activated/dyeing form at the time of application, controlled by adjusting oxidation parameters.
3Stability of the object's composition
If precursors are transformed into salts to decrease degradation rate during storage, then the storage stability is improved, but the hair dyeing performance may be impacted
Solution Approach 1:
The salt form of the precursor is used specifically for storage to enhance stability, then the salt is converted to the free base form immediately before application to restore optimal dyeing performance. This parameter change between storage and use states resolves the contradiction.
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 1-hexyl-1H-pyrazole-4,5-diamine hemisulfate provides enhanced stability and consistent color performance, reducing the formation of degradation products and maintaining color intensity, even after prolonged storage and exposure to environmental factors.
Implementation Method 1
oxidative dyeing of keratin fibers
Data Source
AI summary
1-hexyl-1H-pyrazole-4,5-diamine hemisulfate, as represented in formula (IX-a), and its use in oxidative dyeing composition. This pyrazole salt was found to combine good stability as raw material and good shade intensity with a range of common couplers when formulated in hair dyeing composition.