2-(2-Bromoethyl)-1,3-dioxolane
[CAS# 18742-02-4]

Identification

• Classification: Chemical reagent >> Organic reagent >> Fatty aldehyde (containing acetal, hemiacetal)
• Name: 2-(2-Bromoethyl)-1,3-dioxolane
• Synonyms: 3-Bromopropionaldehyde ethylene acetal
• Molecular Formula: C₅H₉BrO₂
• Molecular Weight: 181.03
• CAS Registry Number: 18742-02-4
• EC Number: 242-551-1
• SMILES: C1COC(O1)CCBr

Properties

• Density: 1.5±0.1 g/cm³ Calc.^*, 1.512 g/mL (Expl.)
• Boiling point: 200.9±15.0 °C 760 mmHg (Calc.)^*, 214.7 - 217.5 °C (Expl.)
• Flash point: 85.0 °C (Calc.)^*, 65 °C (Expl.)
• Solubility: water: insoluble (Expl.)
• Index of refraction: 1.473 (Calc.)^*, 1.479 (Expl.)

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

Safety Data

• Hazard Symbols: GHS06;GHS07 Danger
• Risk Statements: H301-H315-H319-H335
• Safety Statements: P261-P264-P264+P265-P270-P271-P280-P301+P316-P302+P352-P304+P340-P305+P351+P338-P319-P321-P330-P332+P317-P337+P317-P362+P364-P403+P233-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Skin irritation	Skin Irrit.	2	H315
Specific target organ toxicity - single exposure	STOT SE	3	H335
Eye irritation	Eye Irrit.	2	H319
Acute toxicity	Acute Tox.	3	H301
Acute toxicity	Acute Tox.	4	H302
Eye irritation	Eye Irrit.	2A	H319
Flammable liquids	Flam. Liq.	4	H227
Germ cell mutagenicity	Muta.	2	H341

• Transport Information: UN 2810

Discovery and Applications

2‑(2‑Bromoethyl)‑1,3‑dioxolane is a halogenated acetal featuring a five‑membered 1,3‑dioxolane ring substituted at the 2‑position by a bromoethyl side chain Its molecular structure combines an electrophilic bromide and a carbonyl‑protecting acetal ring making it a multifunctional reagent in organic synthesis The bromide moiety undergoes clean nucleophilic substitution reactions with amines thiols azides or organometallic reagents allowing introduction of protected hydroxyethyl or other substituents The acetal ring offers orthogonal protection of aldehyde or ketone functionalities and can be cleaved under mild acidic conditions regenerating reactive carbonyl groups for downstream transformations

This compound is typically prepared by bromination of acetals such as acrolein‑ethylene glycol derivatives under controlled conditions using hydrogen bromide in a solvent such as ethyl acetate or 1,4‑dioxane Recent synthetic developments have improved yield and purity and simplified reagent handling making it more accessible for research and development applications The dual reactivity of the compound enables tandem sequences such as acetal deprotection and immediate functionalization of the released carbonyl or alkylation followed by cleavage in multistep protocols

In medicinal chemistry the compound has been explored as an intermediate to build substituted heterocycles and natural product analogues polymer precursors and as a linker in click chemistry applications In materials science it can serve to introduce protected functional groups onto polymer backbones through halide‑mediated cross‑coupling or click reactions The stability profile under ambient conditions paired with selective reactivity makes it valuable in both solution phase and automated synthesis workflows

Due to its brominated alkyl group and acetal protection standard safety precautions are required to prevent alkylation or acid hydrolysis Its environmental and toxicological properties align with other bromoalkyl acetals which are typically irritants and require care during handling

References

Christensen J B (1994) An economical preparation of 2‑(2‑bromoethyl)‑1,3‑dioxolane Org Prep Proced Int 26 3 355–357 DOI: 10.1080/00304949409458436

Nishio Y Mifune R Sato T Ishikawa S Matsubara H (2017) Hydrogen bromide in 1,4‑dioxane a controlled source for bromination of acrolein acetals Tetrahedron Lett 58 12 1190–1193 DOI: 10.1016/j.tetlet.2017.02.020

Ponaras A A (2001) 2‑(2‑Bromoethyl)‑1,3‑dioxolane Encyclopedia of Reagents for Organic Synthesis John Wiley & Sons Ltd rb291 DOI:10.1002/047084289X.rb291