1-Ethynyl-1-cyclohexanol
[CAS# 78-27-3]

Identification

• Classification: Chemical reagent >> Organic reagent >> Fatty alcohol
• Name: 1-Ethynyl-1-cyclohexanol
• Synonyms: 1-Ethynylcyclohexanol
• Molecular Formula: C₈H₁₂O
• Molecular Weight: 124.18
• CAS Registry Number: 78-27-3
• EC Number: 201-100-9
• SMILES: C#CC1(CCCCC1)O

Properties

• Density: 1.0±0.1 g/cm³ Calc.^*, 0.967 g/mL (Expl.)
• Melting point: 30 - 33 °C (Expl.)
• Boiling point: 174.0 °C 760 mmHg (Calc.)^*, 180 °C (Expl.)
• Flash point: 62.8 °C (Calc.)^*, 73 °C (Expl.)
• Solubility: water: 10 g/L (20 °C) (Expl.)
• Index of refraction: 1.494 (Calc.)^*, 1.483 (Expl.)

^* Calculated using Advanced Chemistry Development (ACD/Labs) Software.

Safety Data

• Hazard Symbols: GHS06;GHS07 Danger
• Risk Statements: H302-H311-H315-H319
• Safety Statements: P262-P264-P264+P265-P270-P280-P301+P317-P302+P352-P305+P351+P338-P316-P321-P330-P332+P317-P337+P317-P361+P364-P362+P364-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Acute toxicity	Acute Tox.	4	H302
Acute toxicity	Acute Tox.	3	H311
Eye irritation	Eye Irrit.	2	H319
Skin irritation	Skin Irrit.	2	H315
Eye irritation	Eye Irrit.	2A	H319
Acute toxicity	Acute Tox.	4	H332
Acute toxicity	Acute Tox.	4	H312

• Transport Information: UN 2811

Discovery and Applications

1-Ethynyl-1-cyclohexanol is an alkynyl alcohol with the molecular formula C₈H₁₂O. Structurally, it consists of a cyclohexane ring substituted at the 1-position with both a hydroxyl group (–OH) and an ethynyl group (–C≡CH), giving a tertiary alcohol bearing a terminal alkyne. The combination of a polar hydroxyl group and a reactive terminal alkyne confers both hydrogen-bonding capability and nucleophilic character at the alkyne carbon. The compound is typically a colorless to pale yellow liquid, soluble in organic solvents such as ethanol, acetone, and dichloromethane, but with limited solubility in water.

1-Ethynyl-1-cyclohexanol is primarily used as a building block in organic synthesis. The terminal alkyne allows for a wide range of reactions, including nucleophilic additions, Sonogashira couplings, and click chemistry, enabling the preparation of more complex molecules such as substituted cyclohexanes, heterocycles, and functionalized alcohols. The hydroxyl group provides an additional site for esterification, etherification, or oxidation reactions, making it versatile for multi-step synthetic routes.

The compound is also employed in the synthesis of pharmaceutical intermediates and specialty chemicals, where the combination of cyclic structure, alkyne functionality, and tertiary alcohol provides a scaffold for introducing functional diversity. Its reactivity and steric properties are particularly useful in stereoselective and regioselective transformations.

Synthetically, 1-ethynyl-1-cyclohexanol can be prepared by the addition of acetylene to cyclohexanone under basic or catalytic conditions, forming the tertiary alcohol with the ethynyl substituent at the 1-position. Handling precautions include avoiding exposure to open flames or strong oxidizing agents, as terminal alkynes are flammable and potentially reactive under certain conditions.

Overall, 1-ethynyl-1-cyclohexanol is a versatile alkynyl alcohol with dual functional groups—a terminal alkyne and a tertiary hydroxyl—attached to a cyclohexane ring. Its structural features and reactivity make it a valuable intermediate in organic synthesis, pharmaceutical development, and the preparation of functionalized cyclic compounds.

References

2023. An insight on medicinal attributes of 1,2,3‐ and 1,2,4‐triazole derivatives as alpha-amylase and alpha-glucosidase inhibitors. Molecular Diversity.
DOI: 10.1007/s11030-023-10728-1