1-Amino-2-hydroxycyclopentane
[CAS 89381-13-5]

Identification

• Classification: Chemical reagent >> Organic reagent >> Alkane
• Name: 1-Amino-2-hydroxycyclopentane
• Synonyms: 2-Aminocyclopentanol; 2-Hydroxycyclopentylamine
• Molecular Formula: C₅H₁₁NO
• Molecular Weight: 101.15
• CAS Registry Number: 89381-13-5
• SMILES: C1CC(C(C1)O)N

Properties

• Solubility: Freely soluble (310 g/L) (25 °C), Calc.^*
• Density: 1.084±0.06 g/cm³ (20 °C 760 Torr), Calc.^*
• Boiling point: 114-115 °C (13 Torr)^**
• Refractive index: 1.4965 (589.3 nm 15 °C)^**
• Flash point: 62.3±25.4 °C, Calc.^*

^* Calculated using Advanced Chemistry Development (ACD/Labs) Software V11.02 (©1994-2013 ACD/Labs)

^** Godchot, Marcel

Safety Data

• Hazard Symbols: GHS05 Danger
• Risk Statements: H314
• Safety Statements: P301+P330+P331-P303+P361+P353-P363-P304+P340-P310-P321-P260-P264-P280-P305+P351+P338-P405-P501
• Transport Information: UN 2735

Discovery and Applications

1-Amino-2-hydroxycyclopentane is a small bifunctional cycloaliphatic compound containing both a primary amine and a secondary alcohol attached to a five-membered cyclopentane ring. Its structure places two polar functional groups on adjacent carbon atoms, making it a simple but versatile building block in organic chemistry.

The cyclopentane ring provides a relatively flexible five-membered carbocyclic framework that can adopt non-planar puckered conformations to minimize torsional strain. Unlike aromatic systems, cyclopentane derivatives do not benefit from delocalized π-electron stabilization, so their conformational behavior is governed mainly by steric interactions and substituent effects.

The amino group at position 1 is a primary amine, which is strongly basic and nucleophilic due to the lone pair of electrons on nitrogen. In aqueous or protic environments, this amine is readily protonated to form an ammonium species. This protonation significantly increases water solubility and influences intermolecular interactions through ionic and hydrogen-bonding forces.

The hydroxyl group at position 2 is a secondary alcohol, capable of acting as both hydrogen bond donor and acceptor. This functionality increases polarity and allows for extensive hydrogen bonding networks in the solid state and in solution. The proximity of the amino and hydroxyl groups also enables potential intramolecular hydrogen bonding depending on conformation.

Because the amino and hydroxyl substituents are adjacent on the ring, 1-amino-2-hydroxycyclopentane is a vicinal amino alcohol. Such motifs are common in organic synthesis and medicinal chemistry, as they serve as key intermediates in the construction of more complex heterocycles, ligands, and biologically active molecules. Vicinal amino alcohols can also be precursors to epoxides, aziridines, or amino sugars depending on subsequent chemical transformations.

From a stereochemical perspective, the compound can exist as different stereoisomers depending on the relative orientation (cis or trans) of the amino and hydroxyl groups on the cyclopentane ring. These stereochemical differences can significantly affect physical properties and reactivity, particularly in reactions involving chiral recognition or enzyme binding.

The presence of both a basic amine and a polar alcohol makes this molecule highly hydrophilic. It is expected to have good solubility in water and polar solvents but limited solubility in nonpolar organic solvents. Its ionic state can vary depending on pH, with the amine protonated under acidic conditions and neutral under basic conditions.

Chemically, the amino group can undergo typical amine reactions such as acylation, alkylation, and condensation with carbonyl compounds to form imines or related derivatives. The hydroxyl group can be oxidized to a ketone or participate in esterification reactions. These two functional groups together allow for diverse synthetic modifications.

Compounds of this type are often used as intermediates in the synthesis of pharmaceutical agents, chiral auxiliaries, or ligands in coordination chemistry. The rigid cyclopentane backbone can help impart defined spatial orientation to functional groups, which is useful in stereoselective synthesis.

Overall, 1-amino-2-hydroxycyclopentane is a simple vicinal amino alcohol with a flexible cyclopentane core and two highly reactive functional groups. Its significance lies in its utility as a polar, multifunctional intermediate in organic synthesis and its potential for further derivatization into more complex chemical structures.

References

2012. DOGS: Reaction-Driven de novo Design of Bioactive Compounds. PLoS Computational Biology.
URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3280956

2002. Biocatalytic Approaches toward the Synthesis of Both Enantiomers of trans-Cyclopentane-1,2-diamine. Organic Letters.
DOI: 10.1021/ol026574l