Phthalimidoperoxycaproic acid
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Product Description
Phthalimidoperoxycaproic acid, commonly known as PAP, is an organic peroxycarboxylic acid (peracid). Its structure consists of a phthalimide group (a bicyclic ring system with aromatic stability and nitrogen functionality) attached to a six-carbon aliphatic caproic acid chain that terminates in a peroxycarboxylic acid group (-C(=O)OOH). This unique structure makes PAP a powerful oxidizing agent with bleaching and disinfecting properties. As a white crystalline solid, PAP is moderately soluble in water and more soluble in polar organic solvents. It is more stable than hydrogen peroxide under storage conditions but decomposes upon heating. PAP is widely used as a bleaching agent in laundry detergents and as a disinfectant in various formulations. Its stability and solid form make it ideal for incorporation into automatic dishwashing tablets and powders. While PAP is a strong oxidizer and requires careful handling, it is a key ingredient in many chlorine-free bleaching and disinfecting products.
Synthesis Methods
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PAP is synthesized by reacting phthalimide with caproic acid in the presence of a peroxidizing agent, typically hydrogen peroxide. This reaction forms a peroxy carboxylic acid (peracid) that is effective as an oxidizing agent.
Uses
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Dental Bleaching: Used in over-the-counter (OTC) teeth whitening products due to its non-irritating nature and effectiveness in removing stains without causing significant enamel erosion.
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Textile Industry: Used as a bleaching agent for textiles.
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Cleaning and Laundry Products: Effective in removing stains and whitening fabrics.
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Personal Care Cosmetics: Found in make-up, fragrances, and shampoos for their bleaching and oxidizing properties.
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Agricultural Sector: Used as an active agent in pesticides.
Mechanism of Action
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PAP works through an epoxidation reaction rather than the typical oxidation-reduction reaction seen with hydrogen peroxide. This forms an epoxide (oxirane) product, which is effective in breaking down chromogens in stains.
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Unlike hydrogen peroxide, PAP does not generate free radicals, which reduces the risk of sensitivity and gingival irritation.
Structural Breakdown
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Phthalimide Group: A bicyclic ring system (benzene fused with an imide) that provides aromatic stability and nitrogen functionality.
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Caproic Acid Chain: A six-carbon aliphatic chain ending in a peroxycarboxylic acid group (-C(=O)OOH), making PAP a peracid and an oxidizing agent.
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Overall Connectivity: The phthalimide nitrogen is attached to the caproic acid chain, and the terminal group is a peroxycarboxyl group responsible for its bleaching/oxidizing properties.
Functional Groups
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Aromatic Imide: Contributes to stability.
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Peroxycarboxylic Acid (-C(=O)OOH): Highly reactive oxidizing group.
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Alkyl Chain (C6 Linker): Provides spacing and lipophilicity.
Properties
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Appearance: White crystalline solid.
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Solubility: Moderately soluble in water, more soluble in polar organic solvents.
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Stability: More stable than hydrogen peroxide under storage but decomposes upon heating.
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pH: PAP solutions can have acidic properties, which may contribute to its bleaching and oxidizing effects.
Safety and Handling
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Hazard Classification: Classified as an oxidizing agent with potential corrosive properties.
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Handling: Requires careful handling due to its oxidizing nature. Personal protective equipment (PPE) including gloves and eye protection is recommended.
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Storage: Should be stored away from heat, sparks, flames, and incompatible materials like reducing agents, strong acids, and bases.
Regulatory Information
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EU Classification: According to the EU cosmetics regulation, PAP is allowed in teeth-whitening products for personal use with a maximum content or release of 0.1% hydrogen peroxide.
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Legal Restrictions: Products containing PAP must comply with specific labeling and registration requirements under the cosmetics regulation.