Piperidine is a cyclic amine consisting of a six-membered ring with one nitrogen atom. It is used in pharmaceuticals, pesticides, and as a solvent for organic reactions.
| IUPAC Name | Piperidine |
| Molecular Formula | C₅H₁₁N |
| CAS Number | 110-89-4 |
| Synonyms | Hexahydropyridine, Azacyclohexane, Cyclopentimine |
| InChI | InChI=1S/C5H11N/c1-2-4-6-5-3-1/h6H,1-5H2 |
Piperidine Properties
Piperidine Formula
The chemical formula of hexahydropyridine is C₅H₁₁N. It consists of five carbon atoms, eleven hydrogen atoms, and one nitrogen atom. The formula represents the exact composition of elements in a molecule of hexahydropyridine.
Piperidine Molar Mass
The molar mass of hexahydropyridine is calculated by adding up the atomic masses of its constituent elements. For hexahydropyridine (C₅H₁₁N), the molar mass is approximately 85.15 grams per mole. This value is useful for determining the amount of hexahydropyridine in a given sample.
Piperidine Boiling Point
Hexahydropyridine has a boiling point of approximately 106 degrees Celsius. This temperature represents the point at which the liquid form of hexahydropyridine changes into a gas. The boiling point is important in various industrial processes that involve the use of hexahydropyridine.
Piperidine Melting Point
The melting point of hexahydropyridine is around -7 degrees Celsius. It indicates the temperature at which solid hexahydropyridine changes into its liquid state. The melting point is a crucial characteristic for handling and storing hexahydropyridine in different applications.
Piperidine Density g/mL
The density of hexahydropyridine is approximately 0.86 grams per milliliter (g/mL). Density refers to the mass of a substance per unit volume. This property is valuable in determining the amount of hexahydropyridine required for specific applications.
Piperidine Molecular Weight
The molecular weight of hexahydropyridine is around 85.15 grams per mole. It represents the sum of the atomic weights of all the atoms present in one molecule of hexahydropyridine. Molecular weight is a vital parameter used in various chemical calculations and reactions involving hexahydropyridine.
Piperidine Structure
Hexahydropyridine has a cyclic structure consisting of a six-membered ring containing one nitrogen atom and five carbon atoms. The arrangement of atoms in this structure affects the chemical properties and behavior of hexahydropyridine. Understanding the structure helps in studying its reactivity and interactions.
Piperidine Solubility
Hexahydropyridine is soluble in both water and organic solvents. It forms hydrogen bonds with water molecules due to the presence of a nitrogen atom. The solubility of hexahydropyridine allows it to be used as a solvent in various chemical processes and as a reagent in organic synthesis.
| Appearance | Clear liquid |
| Specific Gravity | 0.862 g/mL |
| Color | Colorless |
| Odor | Strong, ammoniacal |
| Molar Mass | 85.15 g/mol |
| Density | 0.862 g/mL |
| Melting Point | -7 °C |
| Boiling Point | 106 °C |
| Flash Point | 9 °C |
| Water Solubility | Miscible |
| Solubility | Soluble in polar solvents such as water and organic solvents |
| Vapour Pressure | 7.4 mmHg at 25 °C |
| Vapour Density | 2.95 (air=1) |
| pKa | 11.24 |
| pH | Basic |
Piperidine Safety and Hazards
Hexahydropyridine poses several safety hazards and should be handled with caution. It is irritating to the skin, eyes, and respiratory system. Direct contact may cause burns or irritation. Inhalation of hexahydropyridine vapors can lead to respiratory discomfort and lung damage. It is flammable and can form explosive mixtures with air. When heated, it may release toxic fumes, including nitrogen oxides. Proper ventilation and personal protective equipment, such as gloves and goggles, are necessary when working with hexahydropyridine. Additionally, it should be stored in a cool, well-ventilated area away from sources of ignition. Proper training and awareness of safety protocols are essential for handling hexahydropyridine to minimize potential risks.
| Hazard Symbols | Skull and Crossbones, Flame, Corrosive |
| Safety Description | Avoid contact with skin and eyes. Use in a well-ventilated area. Keep away from ignition sources. |
| UN IDs | UN 2879 (for Piperidine) |
| HS Code | 2933.99.80 |
| Hazard Class | Class 6.1 (Toxic substances) |
| Packing Group | Packing Group II |
| Toxicity | Piperidine is toxic and may cause serious health effects. Inhalation, ingestion, or skin absorption should be avoided. Prolonged or repeated exposure may lead to organ damage or respiratory issues. Proper protective measures should be taken during handling and storage. |
Piperidine Synthesis Methods
There are various methods for synthesizing hexahydropyridine.
One commonly used method involves the reaction of 1,5-dihalopentane with ammonia. In this process, the amino group (-NH2) replaces the halogen atoms by undergoing nucleophilic substitution. Another method involves the reduction of pyridine with hydrogen gas over a catalyst, such as palladium or platinum. This reduction reaction converts pyridine into hexahydropyridine by adding two hydrogen atoms to the nitrogen atom.
Furthermore, the hydrogenation of pyridinium salts or pyridine derivatives yields hexahydropyridine. This hydrogenation process occurs under high pressure and temperature using a suitable catalyst. Another approach involves the reaction of 2,5-dimethylpyrrole with acetylene followed by hydrogenation, which yields hexahydropyridine.
Furthermore, the reductive amination of cyclopentanone or its derivatives with ammonia or primary amines can also lead to hexahydropyridine formation. This reaction involves the addition of an amino group to the ketone group, followed by reduction to form the hexahydropyridine ring.
Overall, these synthesis methods provide routes to obtain hexahydropyridine from various starting materials, allowing for its production in different industrial and research settings. The choice of method depends on factors such as availability of starting materials, desired yield, and specific application requirements.
Piperidine Uses
Hexahydropyridine has several applications across various industries due to its versatile properties. Some common uses of hexahydropyridine include:
- Pharmaceutical Industry: The pharmaceutical industry utilizes hexahydropyridine as a building block to synthesize numerous pharmaceutical compounds. It plays a crucial role in producing drugs such as antihistamines, antipsychotics, analgesics, and antiviral agents.
- Agrochemicals: Hexahydropyridine enhances the effectiveness of pesticides and insecticides, as manufacturers employ it in their production. It enhances the control of pests and improves crop yields.
- Organic Synthesis: Hexahydropyridine acts as a catalyst or solvent in organic reactions, facilitating condensation, cyclization, and oxidation processes. It enables the synthesis of diverse chemical compounds.
- Rubber Industry: In the rubber industry, hexahydropyridine functions as a vulcanization accelerator. It improves the mechanical strength, elasticity, and durability of rubber products by enhancing the cross-linking of rubber polymers.
- Solvent: Hexahydropyridine serves as a solvent for various organic compounds, making it useful in extraction processes, chemical reactions, and as a medium for pharmaceutical formulation. It dissolves a wide range of substances.
- Corrosion Inhibitor: Hexahydropyridine functions as a corrosion inhibitor, protecting metal surfaces from degradation. It forms a protective film on the metal, slowing down or preventing corrosion reactions.
- Laboratory Reagent: Researchers use hexahydropyridine as a reagent in laboratory experiments, particularly in organic chemistry. It actively participates in reactions, such as N-alkylations and ring-opening reactions, facilitating the synthesis of desired compounds.
- Chemical Intermediates: Hexahydropyridine derivatives serve as intermediates in the production of various chemicals, including dyes, fragrances, and surfactants.
These applications demonstrate the diverse and valuable roles that hexahydropyridine plays across multiple industries, contributing to the development of pharmaceuticals, agrochemicals, rubber products, and more.
Questions:
Q: What is the pKa of piperidine?
A: The pKa of hexahydropyridine is approximately 11.24.
Q: What is the pKa of diethyl malonate?
A: The pKa of diethyl malonate is approximately 12.5.
Q: Why is the conjugate acid of morpholine more acidic than the conjugate acid of piperidine?
A: The conjugate acid of morpholine is more acidic due to the presence of an electron-withdrawing oxygen atom in the morpholine ring, which stabilizes the positive charge on the conjugate acid.
Q: How to remove dibenzofulvene-piperidine adduct?
A: Dibenzofulvene-piperidine adduct can be removed by suitable purification techniques like solvent extraction, chromatography, or recrystallization, depending on the specific conditions and desired purity.
Q: What is/are the roles of piperidine in the reaction you performed?
A: Hexahydropyridine can act as a catalyst, base, or reactant, depending on the specific reaction conditions and requirements.
Q: Is piperidine miscible in THF?
A: Yes, hexahydropyridine is miscible in THF (tetrahydrofuran).
Q: What happens when piperidine and DMF are paired?
A: When hexahydropyridine and DMF (dimethylformamide) are combined, they can potentially undergo various reactions depending on the reaction conditions and the presence of other reactants or catalysts.
Q: What is the pH of a solution that is 0.120 M in piperidine and 0.079 M in its chloride salt?
A: The pH of the solution would depend on the pKa of hexahydropyridine and the dissociation of its chloride salt, and would require further calculation to determine the exact pH value.
Q: How to break the piperidine ring?
A: Breaking the hexahydropyridine ring can be achieved through various methods such as oxidation, reduction, or ring-opening reactions, using appropriate reagents and reaction conditions.
Q: Pyridine vs piperidine basicity?
A: Hexahydropyridine is generally more basic than pyridine due to the presence of a more nucleophilic nitrogen atom in its ring, making it more readily able to donate a proton.