Buy Pyridinium p-Toluenesulfonate (PPTS) Online

Pyridinium p-toluenesulfonate (PPTS) is a mild, non-volatile, crystalline organic salt that serves as a weakly acidic catalyst in organic synthesis. It is particularly valued for being soluble in organic solvents and having milder acidity compared to other acid catalysts, which makes it suitable for reactions that require gentle acidic conditions without harsh side reactions.

Chemical Information

• Chemical Formula: C₁₂H₁₅NO₃S

• Molecular Weight: ~253.32 g/mol

• Structure: A salt composed of a pyridinium cation and a p-toluenesulfonate anion.

Preparation

PPTS is commonly prepared by neutralizing pyridine with p-toluenesulfonic acid:

C5H5N+TsOH→[C5H5NH]+[TsO]−text{C}_5text{H}_5text{N} + text{TsOH} rightarrow text{[C}_5text{H}_5text{NH]}^+ text{[TsO]}^-C5​H5​N+TsOH→[C5​H5​NH]+[TsO]−

Where:

• C₅H₅N = pyridine

• TsOH = p-toluenesulfonic acid

Properties

Property	Description
Appearance	White crystalline solid
Solubility	Soluble in alcohols, dichloromethane, THF
Acidity (pKa)	~5 (mild acid strength)
Stability	Stable under ambient conditions
Hygroscopic	Mildly hygroscopic; store in dry conditions

 

Applications in Organic Synthesis

1. Esterification and Transesterification

PPTS is often used as an acid catalyst for esterification of alcohols and carboxylic acids, or for transesterification reactions. Unlike stronger acids (like H₂SO₄ or TsOH), PPTS avoids side reactions like dehydration or polymerization.

2. Acetal and Ketal Formation / Deprotection

PPTS is ideal for forming or removing acetals and ketals under mild acidic conditions. It’s especially useful in protecting groups in multi-step syntheses, such as:

• Deprotection of tetrahydropyranyl (THP) ethers

• Formation of cyclic acetals from aldehydes/ketones and diols

3. Glycosylation Reactions

PPTS is a go-to catalyst in carbohydrate chemistry for activating glycosyl donors, aiding in the formation of glycosidic bonds without decomposing sensitive sugar moieties.

4. Ring-Opening of Epoxides

Mild acid conditions provided by PPTS can be used to selectively open epoxides without rearrangements or overreactions, especially in complex molecules.

Safety and Handling

• Toxicity: Low acute toxicity, but should still be handled with care.

• Irritation: Can cause skin and eye irritation.

• Storage: Store in a cool, dry place away from moisture.

Always consult the Material Safety Data Sheet (MSDS) before use.

Advantages Over Other Acid Catalysts

Catalyst	Relative Acidity	Solubility in Organics	Volatility
PPTS	Mild	Excellent	Non-volatile
TsOH (p-Toluenesulfonic acid)	Strong	Moderate	Non-volatile
H₂SO₄	Very strong	Poor	Non-volatile
Acetic acid	Weak	Good	Volatile

 

Summary

Pyridinium p-toluenesulfonate (PPTS) is a versatile and mild organic acid catalyst that’s essential for chemists working in the areas of:

• Total synthesis

• Protecting group chemistry

• Carbohydrate synthesis

• Natural product synthesis

Its balance of acidity, solubility, and stability makes it an excellent tool for promoting reactions under controlled, gentle conditions — especially when other acids are too harsh.

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