4-Aminopiperidine: Properties, Handling & Lab Protocols

4-Aminopiperidine is a bicyclic secondary amine building block widely used in medicinal chemistry, pharmaceutical synthesis, and materials research for the construction of nitrogen-containing heterocyclic scaffolds.

Chemical Name

4-Aminopiperidine (also known as 4-piperidinylamine)

Molecular Formula

C₅H₁₂N₂

Molecular Weight

100.16 g/mol

Appearance

Colorless to pale yellow liquid or low-melting solid

Key Functional Groups

Secondary cyclic amine (piperidine ring) and primary amine (-NH₂)

Primary Application

Pharmaceutical intermediate and synthetic building block for heterocyclic chemistry

Storage Condition

Store in a cool, dry, well-ventilated area, tightly sealed, away from heat and incompatible materials

SKU

A103195

Chemical Properties and Reactivity

4-Aminopiperidine (CAS: 28522-26-1, MW 100.16 g/mol, formula C₅H₁₂N₂) is a saturated six-membered heterocyclic compound bearing both a ring secondary amine at the nitrogen of the piperidine and a primary amine substituent at the 4-position. This dual-amine functionality confers high reactivity and versatility in organic synthesis.

As a bifunctional amine, 4-Aminopiperidine can participate in a wide range of reactions: the primary amine undergoes acylation, sulfonylation, reductive amination, and condensation with carbonyl compounds, while the ring nitrogen can be alkylated or acylated independently under appropriate conditions. This orthogonal reactivity makes it a valuable scaffold for the synthesis of pharmaceutically relevant piperidine-containing structures, including kinase inhibitors, CNS-active agents, and GPCR modulators.

The compound is a moderate-to-strong base owing to the presence of two nitrogen atoms; both amines are protonatable, with the primary amine typically exhibiting a higher basicity contribution in aqueous environments. Researchers should account for pH effects when conducting reactions in buffered aqueous media.

Safety and Handling

Personal Protective Equipment (PPE): Always wear appropriate PPE when working with 4-Aminopiperidine. This includes chemical-resistant gloves (nitrile or neoprene), a laboratory coat, and safety goggles. When handling large quantities or performing open manipulations, use a face shield and work inside a certified chemical fume hood.

Inhalation and Skin Contact Hazards: 4-Aminopiperidine is an amine compound that may cause irritation to skin, eyes, and the respiratory tract. Avoid breathing vapors or mists. In case of skin contact, immediately wash with copious amounts of water for at least 15 minutes. In case of eye contact, rinse thoroughly with water and seek immediate medical attention.

Incompatibilities: Keep 4-Aminopiperidine away from strong oxidizing agents, strong acids, and acid chlorides, as violent reactions may occur. Avoid contact with moisture if long-term stability is required.

Waste Disposal: Dispose of waste material in accordance with local, regional, and national regulations. Do not pour down the drain. Amine-containing waste should be neutralized and handled as chemical waste by a licensed contractor.

Emergency Procedures: In the event of a spill, ventilate the area, avoid direct contact, and absorb the material with inert absorbent (e.g., vermiculite or dry sand). Collect and place in a sealed container for proper disposal.

Solution Preparation Protocol

Step 1 – Select an Appropriate Solvent: 4-Aminopiperidine is miscible with water and soluble in common polar solvents such as methanol, ethanol, dimethyl sulfoxide (DMSO), and dimethylformamide (DMF). For aqueous stock solutions, deionized water is recommended. For anhydrous reactions, ensure the solvent is dried prior to use.

Step 2 – Calculate Required Mass: Use the formula: mass (g) = desired concentration (mol/L) × volume (L) × molecular weight (100.16 g/mol). Example: to prepare 100 mL of a 1.0 M aqueous solution, weigh out 10.016 g of 4-Aminopiperidine.

Step 3 – Dissolve the Compound: Add approximately 80% of the total target solvent volume to a clean, dry volumetric flask. Carefully add the weighed 4-Aminopiperidine and stir or swirl gently until completely dissolved. The dissolution process is typically rapid due to the high polarity of the compound.

Step 4 – Adjust Volume and pH (if required): Make up to the final volume with solvent. If the experiment requires a specific pH, use a calibrated pH meter and adjust with dilute acid (e.g., HCl) as needed, noting that 4-Aminopiperidine solutions are inherently basic.

Step 5 – Storage of Prepared Solutions: Store solutions tightly sealed at 2–8 °C under inert atmosphere (nitrogen or argon) if prolonged storage is required. Prepare fresh solutions where possible to ensure maximal reactivity and purity.

Storage and Stability Guidelines

Recommended Storage Conditions: Store 4-Aminopiperidine (SKU: A103195) in a tightly sealed container in a cool, dry, well-ventilated area, away from direct sunlight and heat sources. Recommended storage temperature is 2–25 °C. Refrigerated storage at 2–8 °C is preferred for long-term preservation of purity.

Container Integrity: Always reseal the container immediately after use. Prolonged exposure to air may lead to gradual oxidation or carbonation of the amine groups through reaction with atmospheric CO₂, forming carbamate species and potentially reducing reagent efficacy.

Moisture Sensitivity: Although 4-Aminopiperidine is water-miscible, repeated exposure to atmospheric humidity may promote hydroscopic behavior in certain formulations. When high purity is critical, dispense under an inert atmosphere (nitrogen or argon) using a dry syringe or cannula.

Shelf Life: When stored under recommended conditions and in an unopened container, 4-Aminopiperidine is expected to maintain its specified purity for the duration of the stated expiry period on the product label. Verify purity by NMR or GC analysis if the reagent has been stored for extended periods after opening.

Incompatible Storage: Do not store alongside strong oxidizers, strong acids, or halogenated solvents. Segregate in accordance with chemical compatibility guidelines.

Synthetic Applications and Use Cases

Pharmaceutical Intermediate: 4-Aminopiperidine is a key building block in medicinal chemistry. Its piperidine scaffold is found in numerous approved pharmaceuticals and drug candidates. The bifunctional amine allows chemists to introduce it as a linker or pharmacophore element in multi-step syntheses of kinase inhibitors, antipsychotics, analgesics, and antihistamines.

Reductive Amination: The primary amine of 4-Aminopiperidine reacts with aldehydes and ketones in the presence of a reducing agent (e.g., sodium cyanoborohydride or sodium triacetoxyborohydride) to furnish N-substituted piperidine derivatives. This is a common and efficient route to libraries of diversely substituted compounds for structure–activity relationship (SAR) studies.

Acylation and Sulfonylation: Reaction of 4-Aminopiperidine with acid chlorides, anhydrides, or sulfonyl chlorides selectively acylates or sulfonylates the primary amine under mild conditions (0 °C to room temperature, in the presence of base such as triethylamine) to provide amides and sulfonamides of pharmaceutical relevance.

Heterocyclic Synthesis: 4-Aminopiperidine serves as a precursor in the construction of fused ring systems, diketopiperazines, and other nitrogen-rich scaffolds via condensation reactions with bifunctional electrophiles. These products are valuable intermediates in fragment-based drug discovery programs.

Materials Science: Beyond pharmaceutical applications, 4-Aminopiperidine has been explored as a curing agent for epoxy resins and as a building block in the synthesis of functional polymers and metal–organic frameworks (MOFs), leveraging its dual amine groups for crosslinking or coordination chemistry.

Frequently asked questions

What solvents are compatible with 4-Aminopiperidine for stock solution preparation?

4-Aminopiperidine is miscible with water and soluble in polar organic solvents including methanol, ethanol, DMSO, and DMF. For most biological assay applications, aqueous solutions or DMSO stocks are preferred. Ensure the solvent is appropriate for your downstream application and that anhydrous solvents are used when moisture sensitivity is a concern.

How should 4-Aminopiperidine be stored to maintain purity over time?

Store 4-Aminopiperidine in a tightly sealed container at 2–8 °C in a cool, dry, well-ventilated area away from oxidizers, strong acids, and light. After opening, reseal immediately and consider dispensing under an inert gas (nitrogen or argon) to minimize oxidation and carbonation. Verify purity by NMR or GC if the reagent has been stored for an extended period after opening.

What are the main safety precautions when working with 4-Aminopiperidine in the laboratory?

Always handle 4-Aminopiperidine in a certified fume hood wearing nitrile gloves, a lab coat, and safety goggles. The compound may cause irritation to skin, eyes, and the respiratory tract. In case of skin or eye contact, rinse immediately with plenty of water and seek medical advice. Dispose of waste according to local chemical waste regulations.

Can 4-Aminopiperidine be used for reductive amination reactions?

Yes. The primary amine group of 4-Aminopiperidine readily undergoes reductive amination with aldehydes and ketones in the presence of mild reducing agents such as sodium cyanoborohydride (NaBH₃CN) or sodium triacetoxyborohydride (NaBH(OAc)₃). This reaction is widely employed in medicinal chemistry to generate structurally diverse N-substituted piperidine libraries for SAR studies.

What is the molecular weight and formula of 4-Aminopiperidine?

4-Aminopiperidine has the molecular formula C₅H₁₂N₂ and a molecular weight of 100.16 g/mol. This information is essential for accurate preparation of molar solutions and for stoichiometric calculations in synthetic protocols.

References

1. March, J. Advanced Organic Chemistry: Reactions, Mechanisms, and Structure. 4th ed. Wiley-Interscience, 1992. (General reference for amine reactivity and reductive amination protocols.)
2. Clayden, J.; Greeves, N.; Warren, S. Organic Chemistry. 2nd ed. Oxford University Press, 2012. (Textbook-level reference for heterocyclic amine chemistry.)
3. Abdel-Magid, A. F.; Mehrman, S. J. A Review on the Use of Sodium Triacetoxyborohydride in the Reductive Amination of Ketones and Aldehydes. Organic Process Research & Development, 2006, 10, 971–1031. doi:10.1021/op0601013

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