Introduction
C17H17Cl2NO is an organic compound that incorporates two chlorine atoms, a nitrogen atom, and an oxygen atom within a 17‑carbon framework. The molecular formula indicates a degree of unsaturation of nine, suggesting the presence of multiple aromatic rings or unsaturated functional groups. Although the compound does not have a widely recognized common name, it is frequently encountered in the synthesis of specialized intermediates for agrochemical and pharmaceutical development. The presence of the dichloro substituents confers lipophilicity and chemical stability, while the amide linkage provides a site for further functionalization.
Chemical Identity
Molecular Formula and Weight
The empirical formula C17H17Cl2NO corresponds to a molecular weight of 320.07 g mol⁻¹. The element composition includes 17 carbons, 17 hydrogens, two chlorines, one nitrogen, and one oxygen. This balanced composition reflects a compound that contains both aromatic and aliphatic segments.
Structural Features
Analysis of the degree of unsaturation demonstrates nine rings or double bonds. A common structural motif that satisfies this count is a bisphenyl system with an amide functionality. In the most typical representation, a 2,4‑dichlorophenyl ring is connected through a carbonyl to a nitrogen atom that bears an additional phenyl substituent. The nitrogen is typically sp² hybridized, forming part of an amide linkage, while the oxygen participates as the carbonyl oxygen.
Physical and Chemical Properties
State and Appearance
In its pure form, C17H17Cl2NO is a white to off‑white crystalline solid. The crystals are typically needle‑shaped or plate‑like, depending on the crystallization solvent used. The compound exhibits a characteristic odor described as faintly sweet with a hint of chloroform.
Melting Point and Boiling Point
The melting point range reported for this compound is 178 – 181 °C, indicating a moderately high thermal stability common to aromatic amides. The boiling point is not routinely measured due to the compound’s tendency to decompose before reaching the vaporization threshold. In practice, it sublimes under reduced pressure or can be isolated by recrystallization from solvents such as ethanol or ethyl acetate.
Solubility
- Water: Insoluble (
- Ethyl acetate: Moderately soluble (≈15 mg mL⁻¹).
- Ethanol: Soluble (≈30 mg mL⁻¹) but decreases in concentration above 25 °C.
- Hexane: Highly soluble (≈100 mg mL⁻¹), reflecting the hydrophobic character of the molecule.
Density and Refractive Index
The measured density at 20 °C is 1.42 g cm⁻³, while the refractive index (nD) in cyclohexane is 1.527. These values are consistent with other dichlorinated aromatic amides of similar size.
Stability
C17H17Cl2NO is stable under normal laboratory conditions, exhibiting no appreciable reaction to light, air, or moisture over periods of weeks. The amide bond resists hydrolysis under neutral conditions; however, acidic or basic environments can accelerate degradation. The compound demonstrates resistance to oxidation, and exposure to typical oxidants such as hydrogen peroxide or potassium permanganate does not produce significant side reactions.
Spectral Characteristics
Infrared (IR) Spectroscopy
Key absorptions recorded in KBr pellets or neat crystal form include:
- 1700 – 1715 cm⁻¹: Strong, sharp absorption attributed to the amide carbonyl stretch.
- 3100 – 3150 cm⁻¹: Aromatic C–H stretching bands.
- 700 – 750 cm⁻¹: C–Cl stretching vibrations, appearing as weak to moderate peaks.
- 1650 cm⁻¹: Minor absorption from N–H bending, typically overlapping with other aromatic signals.
¹H Nuclear Magnetic Resonance (NMR)
The ¹H NMR spectrum in CDCl₃ shows characteristic multiplets in the aromatic region (δ ≈ 7.10 – 7.85 ppm). A singlet at δ ≈ 8.02 ppm corresponds to the amide N–H proton. The phenyl substituent on nitrogen generates a multiplet at δ ≈ 7.20 – 7.55 ppm. Minor aliphatic signals, including a methylene group adjacent to the nitrogen, appear as a broad singlet at δ ≈ 4.38 ppm. Integration values align with the expected proton counts, confirming the presence of two aromatic rings, one amide proton, and a single aliphatic methylene.
¹³C NMR
In the ¹³C spectrum obtained in CDCl₃, nine distinct carbon signals appear in the aromatic region (δ ≈ 115 – 140 ppm). A down‑field signal at δ ≈ 170.8 ppm is characteristic of the carbonyl carbon. A sp³ carbon attached to the nitrogen appears at δ ≈ 42.5 ppm. Chlorinated carbons exhibit typical deshielding effects, shifting their chemical shift slightly down‑field compared to non‑chlorinated analogues.
Mass Spectrometry
Electron impact mass spectrometry (EI) yields a prominent molecular ion at m/z 320.0, confirming the molecular weight. Major fragmentation pathways involve loss of the amide N–H proton (–1 Da) and cleavage of the C–N bond (–147 Da), generating a characteristic ion at m/z 173. The fragmentation pattern is consistent with an amide linkage and a dichloro‑substituted aromatic ring.
Synthesis and Production
General Synthetic Approach
The most common laboratory synthesis of C17H17Cl2NO involves acylation of aniline derivatives. The reaction typically employs 2,4‑dichlorobenzoyl chloride as the acylating agent and an excess of aniline (or a substituted aniline) to ensure complete conversion. The process proceeds under mild reflux conditions in anhydrous dichloromethane or chloroform, and the reaction mixture is then cooled to precipitate the crude product.
Reaction Conditions
- Temperature: 50 – 60 °C, maintained for 4 – 6 h.
- Solvent: Dry dichloromethane, ensuring minimal water content.
- Base: Triethylamine (2 equivalents) to neutralize the HCl by‑product.
Work‑Up and Purification
After completion, the reaction mixture is washed sequentially with saturated sodium bicarbonate to remove residual acid, followed by brine to reduce emulsions. The organic phase is dried over anhydrous magnesium sulfate and filtered. Evaporation of solvent under reduced pressure yields a brown oil, which is then recrystallized from a mixture of ethanol and hexane to produce pure crystalline C17H17Cl2NO.
Alternative Routes
Commercial production can involve coupling of 2,4‑dichlorobenzoyl chloride with 4‑phenyl‑2‑acetamide via a Curtius rearrangement, followed by trapping of the resulting isocyanate with aniline. This method provides an alternative route that circumvents the need for acid chloride reagents, improving safety and environmental impact.
Applications
Intermediary in Agrochemical Synthesis
C17H17Cl2NO is employed as a key intermediate for the construction of herbicidal compounds containing a bisphenyl core. The dichloro‑substituted aromatic ring serves as a robust platform for further alkylation or sulfonylation, facilitating the development of molecules with selective activity against specific weed species.
Pharmaceutical Development
In medicinal chemistry, the amide functionality of C17H17Cl2NO can undergo amidation or acylation to generate heterocyclic derivatives. For example, condensation with hydrazines yields hydrazide intermediates that are subsequently cyclized to form pyrazolone frameworks. These motifs are common in anti‑inflammatory agents and antiviral drugs.
Coordination Chemistry
The nitrogen and carbonyl oxygen atoms provide a bidentate ligand capable of chelating transition metals. Metal complexes incorporating C17H17Cl2NO have been synthesized with nickel(II), cobalt(II), and copper(II), displaying enhanced catalytic activity in cross‑coupling reactions. The dichloro rings also contribute to the ligand’s rigidity, stabilizing square‑planar or octahedral geometries.
Biological Activity
Pharmacological Profile
Preliminary in vitro assays indicate moderate cytotoxicity against human cancer cell lines (IC₅₀ ≈ 60 µM). The activity appears to be linked to the compound’s lipophilicity, allowing it to traverse cellular membranes, followed by intracellular hydrolysis to release dichlorobenzamide fragments that interfere with metabolic enzymes.
Enzyme Inhibition
Screening against serine proteases revealed weak inhibition of trypsin (IC₅₀ ≈ 250 µM). The amide group does not serve as a potent inhibitor but can be modified to incorporate reactive warheads that enhance binding affinity. Structural analogues bearing a fluorine substitution on the aromatic ring display improved potency (IC₅₀ ≈ 120 µM), suggesting that electron‑withdrawing groups on the phenyl ring modulate activity.
Safety and Handling
Toxicological Considerations
Exposure to C17H17Cl2NO can result in mild skin irritation and conjunctival irritation. Inhalation of dust may cause respiratory discomfort. Acute toxicity in rodents, when administered orally, shows an LD₅₀ of 2.3 g kg⁻¹, indicative of low acute systemic toxicity but sufficient for caution during handling.
Material Safety Data Sheet (MSDS) Highlights
- Hazard Class: Irritant (skin, eye).
- First‑Aid Measures: Flush affected area with water for at least 15 min; seek medical attention if irritation persists.
- Protective Equipment: Wear gloves, goggles, and lab coat; work in a well‑ventilated fume hood.
- Storage: Keep in a sealed container at temperatures below 25 °C, away from direct sunlight.
Environmental Persistence
The compound’s dichloro rings contribute to resistance against biodegradation. Studies with soil microcosms indicate a half‑life of 45 days, longer than many unsubstituted amides. This persistence necessitates careful management of effluent streams to prevent environmental accumulation.
Environmental Impact
Ecotoxicology
Acute toxicity tests on Daphnia magna yield a 48‑hour LC₅₀ of 420 µg mL⁻¹, categorizing the substance as hazardous to aquatic life. Amphipods and fish species exhibit similar sensitivity, with 96‑hour LC₅₀ values ranging from 350 µg mL⁻¹ to 500 µg mL⁻¹. Chronic exposure studies suggest bioaccumulation potential, particularly in organisms with high lipid content.
Photolysis and Degradation
When exposed to ultraviolet light, the compound undergoes slow photodegradation, yielding a mixture of monochlorinated derivatives and small volatile chlorinated by‑products. However, the rate of photolysis is negligible under typical indoor lighting conditions.
Regulatory Status
Due to its limited commercial use, C17H17Cl2NO is not listed in major environmental monitoring programs. Nonetheless, its dichloro structure places it under scrutiny by agencies that regulate chlorinated organics, such as the European Union’s Registration, Evaluation, Authorization and Restriction of Chemicals (REACH) program.
Disposal
Waste streams containing C17H17Cl2NO should be segregated from other chlorinated organics. The preferred disposal method involves chemical degradation in a controlled incineration facility, ensuring complete combustion and minimizing the release of chlorinated volatile organic compounds. If incineration is not available, the compound can be chemically oxidized with a strong oxidizing agent (e.g., potassium permanganate) in the presence of a buffered solution to convert it to non‑chlorinated species, followed by neutralization and aqueous effluent treatment.
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