1-Phenyl-2-nitropropene
[CAS# 705-60-2]

Identification

• Classification: Organic raw materials >> Hydrocarbon compounds and their derivatives >> Acyclic hydrocarbon
• Name: 1-Phenyl-2-nitropropene
• Synonyms: 2-Nitro-1-phenylpropene
• Molecular Formula: C₉H₉NO₂
• Molecular Weight: 163.17
• CAS Registry Number: 705-60-2
• EC Number: 627-363-3
• SMILES: C/C(=C\C1=CC=CC=C1)/[N+](=O)[O-]

Properties

• Density: 1.1±0.1 g/cm³ Calc.^*, 1.1 g/mL (Expl.)
• Melting point: 63 - 65 ºC (Expl.)
• Boiling point: 263.0±9.0 ºC 760 mmHg (Calc.)^*, 254 - 272 ºC (Expl.)
• Flash point: 115.7±11.5 ºC (Calc.)^*
• Index of refraction: 1.586 (Calc.)^*

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

Safety Data

• Hazard Symbols: GHS07 Warning
• Hazard Statements: H302-H315-H319-H335
• Precautionary Statements: P261-P264-P264+P265-P270-P271-P280-P301+P317-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
Eye irritation	Eye Irrit.	2	H319
Skin irritation	Skin Irrit.	2	H315
Specific target organ toxicity - single exposure	STOT SE	3	H335
Acute toxicity	Acute Tox.	4	H302

Discovory and Applicatios

1-Phenyl-2-nitropropene is an organic compound with the molecular formula C₉H₉NO₂, categorized as an α,β-unsaturated nitroalkene. It is structurally characterized by a phenyl ring bonded to a nitropropene side chain, with the nitro group positioned on the terminal carbon of the alkene. This compound has served as a crucial synthetic intermediate in organic chemistry, with a well-documented history of preparation and application in both academic and industrial contexts.

The synthesis of 1-phenyl-2-nitropropene was first explored in the early 20th century, utilizing a condensation reaction between benzaldehyde and nitroethane under basic conditions. This transformation, commonly known as the Henry reaction or nitroaldol condensation, involves nucleophilic addition of the deprotonated nitroethane to the carbonyl group of benzaldehyde, followed by dehydration to yield the nitroalkene. The reaction proceeds smoothly under mild conditions using bases such as sodium hydroxide, potassium carbonate, or ammonium acetate in alcoholic solvents. This synthetic route remains the standard method for laboratory-scale preparation and is frequently included in undergraduate organic chemistry curricula to illustrate carbon–carbon bond formation.

Applications of 1-phenyl-2-nitropropene are primarily centered around its role as a versatile intermediate in the synthesis of biologically active compounds. One of its most studied transformations is the catalytic or chemical reduction of the nitro group to an amine, producing 1-phenyl-2-aminopropane derivatives. These phenethylamines are significant in medicinal chemistry, where various analogs have been evaluated for activity in central nervous system modulation, including compounds used as decongestants or investigated as stimulants. Several phenylpropanes synthesized from this nitroalkene have been assessed for their pharmacological properties during the development of therapeutic agents.

Beyond its utility in pharmaceutical precursors, 1-phenyl-2-nitropropene has been employed in heterocycle synthesis. The electrophilic nature of the conjugated nitroalkene system enables reactions with a wide variety of nucleophiles, including amines and thiols, leading to the formation of substituted heterocycles such as oxazoles and thiazoles. These reactions are of interest in the field of agrochemicals and dyes, where such heterocycles often serve as functional components due to their electron-rich and structurally diverse frameworks.

The compound’s electronic structure, featuring conjugation between the nitro group and the double bond, lends it distinctive reactivity in Michael addition reactions and cycloaddition processes. These properties have been exploited in synthetic strategies aimed at building complex molecular architectures, including natural product analogs and advanced pharmaceutical intermediates. Several synthetic methodologies involving 1-phenyl-2-nitropropene have been optimized using green chemistry approaches, such as solvent-free conditions, solid-supported reagents, or ionic liquid media, reflecting growing interest in environmentally sustainable practices.

Analytical characterization of 1-phenyl-2-nitropropene typically involves techniques such as infrared spectroscopy, which reveals strong absorptions corresponding to the nitro group stretching modes, and nuclear magnetic resonance spectroscopy, which confirms the presence of the alkene and aromatic protons. It is generally isolated as a yellow crystalline solid with moderate thermal stability. Due to the presence of the nitro group, it should be handled with appropriate precautions, as nitro compounds can pose hazards under extreme thermal or reductive conditions.

The importance of 1-phenyl-2-nitropropene in modern chemistry lies in its function as a model substrate for mechanistic studies and its continued relevance in applied organic synthesis. It is also frequently used as a benchmark compound in the testing of new catalytic systems or reaction protocols for carbon–carbon and carbon–nitrogen bond formation. Ongoing research continues to investigate its reactivity under various conditions to develop novel transformations and improve existing synthetic methodologies.

References

2024. High-Yielding Syntheses, Crystal Structures and Hirshfeld Surface Analysis of Bis-1,1'-(2-nitropropenes) Extended with Benzene-1,4-diyl and Biphenyl-4,4'-diyl Spacers. Journal of Chemical Crystallography, 54(5).
DOI: 10.1007/s10870-024-01032-3

2020. Enantioselective synthesis of 4,5-disubstituted pyrrolidin-2-one derivatives with two stereocenters on the basis of Michael adducts. Chemistry of Heterocyclic Compounds, 56(8).
DOI: 10.1007/s10593-020-02766-6

2011. Indium Triflate-Catalyzed Coupling between Nitroalkenes and Phenol/Naphthols: A Simple and Direct Synthesis of Arenofurans by a Cyclization Reaction. Chemistry � An Asian Journal, 6(1).
DOI: 10.1002/asia.201000869