Introduction
The molecular formula C11H15NO represents a class of organic compounds comprising eleven carbon atoms, fifteen hydrogen atoms, one nitrogen atom, and one oxygen atom. This stoichiometry allows for a variety of structural motifs, including heteroaromatic rings, aliphatic chains, and functional groups such as amines, amides, alcohols, and esters. Compounds with this formula are of interest in medicinal chemistry, materials science, and synthetic organic chemistry due to their moderate size and the presence of both nitrogen and oxygen heteroatoms, which often confer significant biological activity or useful physicochemical properties.
While the formula itself does not uniquely identify a single molecule, it does set constraints on the possible degree of unsaturation and the types of functional groups that may coexist. Using the index of hydrogen deficiency (IHD) calculation, C11H15NO has a degree of unsaturation of six, indicating that any isomer must contain a combination of rings and/or multiple bonds accounting for these six units. This allows for the presence of aromatic systems, alkenes, carbonyl groups, or a combination thereof.
In this article, the molecular formula is examined from multiple perspectives: the general structural features it permits, representative compounds that fall under this formula, common synthetic routes, typical applications, and safety considerations. The discussion is intended for chemists, pharmacologists, and materials scientists who may encounter C11H15NO species in research or industrial settings.
Chemical Properties
Degree of Unsaturation and Structural Diversity
Applying the double bond equivalence rule, the formula C11H15NO corresponds to six degrees of unsaturation. Each ring or π-bond consumes one degree, meaning that a C11H15NO molecule might contain a single aromatic ring (four degrees) and an additional alkene or carbonyl (two degrees), or a fused bicyclic system, or multiple double bonds. The heteroatoms nitrogen and oxygen can participate in various functional groups: amine (–NH–), amide (–C(=O)NH–), alcohol (–OH), ether (–O–), or ester (–C(=O)O–). The presence of these groups can alter the overall polarity, hydrogen-bonding capability, and reactivity of the molecule.
Physical Characteristics
Typical C11H15NO compounds are small organic molecules with molecular weights ranging from 173 to 175 g/mol, depending on isotopic composition. They usually crystallize as colorless or pale yellow solids, though liquid forms are also common for molecules with flexible aliphatic chains. The melting points of crystalline isomers can vary widely, from modest temperatures near 30 °C for highly conjugated systems to over 200 °C for highly rigid, planar structures. Solubility in common organic solvents such as dichloromethane, ethanol, and acetone is generally good, whereas aqueous solubility is moderate to low unless polar functional groups are present.
Reactivity Overview
The reactivity of C11H15NO compounds is largely governed by the functional groups present. Aliphatic amines are prone to protonation, forming salts, and can undergo acylation or alkylation reactions. Amides are relatively stable but can be hydrolyzed under strongly acidic or basic conditions. Alcohols undergo oxidation to aldehydes or ketones, and can be converted to halides or tosylates. Aromatic heterocycles such as indoles or pyridines undergo electrophilic substitution, while alkenes can participate in addition reactions. The presence of a nitrogen atom often facilitates the formation of hydrogen bonds, influencing the compound's interaction with biological targets or solvent molecules.
Synthesis
General Synthetic Strategies
The synthesis of C11H15NO compounds typically involves building blocks that introduce both the nitrogen and oxygen atoms early in the synthetic sequence. Common strategies include nucleophilic substitution, amide coupling, and condensation reactions. A general approach might start from a 1,2-diol or a 1,2-amine-2-ol precursor, followed by protection and functionalization steps to construct the desired heteroatom arrangement.
Specific Reaction Pathways
- Condensation of an α‑ketoester with an amine to form an amide: A classic route involves reacting a β‑ketoester (C₅H₇O₂) with a primary amine (C₆H₁₃N) under acidic conditions to yield a β‑keto amide, which can then undergo intramolecular cyclization to generate heterocyclic frameworks.
- Reductive amination of ketones: A ketone bearing a suitable carbon skeleton (C₁₀H₁₃O) can be reacted with methylamine to give a secondary amine; subsequent oxidation of the alcohol to a carbonyl group generates an imine intermediate that is reduced to furnish the desired product.
- Piperidine or pyrrolidine ring construction: Starting from a 1,4-dicarbonyl compound, nucleophilic attack by a nitrogen source (e.g., ammonium chloride) followed by cyclization can produce saturated heterocycles with a single nitrogen atom.
- Esterification followed by amidation: A carboxylic acid derivative (C₁₀H₁₃O₂) can be esterified with methanol to form a methyl ester (C₁₁H₁₅NO₂). Subsequent amide bond formation with an amine leads to the C11H15NO skeleton, with elimination of methanol.
Key Reagents and Conditions
Typical reagents employed in the synthesis of C11H15NO compounds include:
- Lewis acids such as zinc chloride or aluminum chloride for electrophilic aromatic substitution.
- Strong bases (e.g., sodium hydride, lithium diisopropylamide) for deprotonation and formation of anions used in nucleophilic substitution.
- Redox agents: sodium borohydride for reductions, PCC (pyridinium chlorochromate) for oxidations.
- Coupling agents: DCC (dicyclohexylcarbodiimide) or HATU for amide bond formation.
- Protecting groups: Boc (tert-butoxycarbonyl) for amines and TBDMS (tert-butyldimethylsilyl) for alcohols to control selectivity.
Applications
Pharmaceutical Relevance
Compounds with the C11H15NO formula have been explored as therapeutic agents or as intermediates in drug synthesis. Their moderate size and the presence of heteroatoms make them suitable for interaction with protein targets. Examples include inhibitors of enzymes such as monoamine oxidase, dopamine reuptake inhibitors, and molecules with antipsychotic activity. Their pharmacokinetic properties can be tuned by modifying substituents on the aromatic or aliphatic portions, thereby optimizing absorption, distribution, metabolism, and excretion (ADME) characteristics.
Materials Science
In materials chemistry, C11H15NO derivatives serve as monomers or building blocks for polymer synthesis. The nitrogen atom can act as a coordination site for metal centers, enabling the formation of metal–organic frameworks (MOFs) with tailored porosity. Additionally, the compounds are used as plasticizers, flame retardants, or additives that improve the flexibility and durability of polymeric materials. Their ability to participate in hydrogen bonding and π–π interactions also facilitates the formation of supramolecular assemblies with desirable optical or electronic properties.
Analytical Standards and Probes
Due to their well-defined mass and stable isotopic composition, certain C11H15NO molecules are employed as internal standards in chromatographic and mass spectrometric analyses. They are also utilized as fluorescent probes in biochemical assays, where the nitrogen-oxygen framework confers suitable photophysical characteristics such as high quantum yield and photostability.
Biological Activity
Interaction with Enzymes
Several C11H15NO compounds act as competitive inhibitors for key enzymes. For instance, molecules bearing a β-keto amide core can mimic transition states of esterases, thereby blocking catalytic activity. The presence of an amine side chain often enhances binding affinity through hydrogen bonding with active site residues. Enzyme inhibition studies typically measure IC₅₀ values in the nanomolar to micromolar range, indicating potent activity.
Neurotransmitter Modulation
Structural motifs common to neurotransmitters, such as the indole ring, can be incorporated into C11H15NO frameworks. These analogues exhibit the ability to cross the blood–brain barrier and modulate serotonergic or dopaminergic signaling. In vitro assays using cultured neuronal cells reveal that such compounds can alter neurotransmitter release, receptor binding, and downstream signaling pathways. In vivo studies in rodent models further support their activity as modulators of mood and cognition.
Antimicrobial Properties
Some C11H15NO derivatives demonstrate antibacterial or antifungal activity, often attributed to disruption of cell wall synthesis or interference with nucleic acid processes. Minimum inhibitory concentration (MIC) assays against Gram-positive bacteria like Staphylococcus aureus typically yield values between 5 and 50 µg/mL, suggesting moderate potency. The exact mechanism is frequently linked to the compound's ability to intercalate into DNA or inhibit topoisomerase enzymes.
Known Compounds
Representative Examples
- 3-(4-Methylphenyl)-1-aminopropan-1-ol – an amine bearing a p-methylphenyl group and a primary alcohol; used as a building block for pharmaceutical intermediates.
- 2-(2-Methyl-1H-indol-3-yl)acetamide – an indole derivative featuring an amide linkage; studied as a selective monoamine oxidase B inhibitor.
- 4-(1-Methylpyrrolidin-2-yl)butan-1-ol – a cyclic amine with an alcohol side chain; explored in the design of antihypertensive agents.
- 1-(4-Methylphenyl)-1H-pyrrol-2-yl acetate – an ester containing a pyrrole core; employed as a synthetic intermediate for bioactive heterocycles.
Isomeric Diversity
Given the degree of unsaturation, C11H15NO compounds can exist in various isomeric forms:
- Aromatic–aliphatic hybrids – one aromatic ring plus a saturated side chain with an amine or alcohol group.
- Alkene-containing isomers – linear or cyclic alkenes combined with heteroatoms in a way that preserves overall hydrogen count.
- Ring-fused systems – bicyclic or tricyclic frameworks that integrate nitrogen into the ring system, often generating rigid structures.
- Amide and ester isomers – differentiation between amide and ester functional groups can lead to distinct physicochemical properties.
Safety and Handling
General Precautions
Compounds with the C11H15NO formula are typically handled under standard laboratory safety protocols. They are generally classified as low to moderate hazard substances, depending on specific functional groups. Protective equipment, such as gloves, goggles, and lab coats, should be worn to prevent dermal or ocular contact. Ventilation is recommended, particularly during reactions that release volatile byproducts or when working with solvents of high toxicity.
Toxicological Profile
Acute toxicity data for most C11H15NO compounds indicate low oral LD₅₀ values (>500 mg/kg) in rodent models, suggesting moderate acute toxicity. However, chronic exposure studies reveal potential for hepatic enzyme induction, especially for compounds containing aromatic amines. Inhalation exposure is generally considered low risk, though dust or vapor inhalation should be avoided. In case of ingestion or skin contact, immediate washing with water and medical evaluation are advised.
Environmental Impact
These compounds typically exhibit moderate biodegradability. Their environmental persistence is largely influenced by the presence of aromatic rings and heteroatoms that can facilitate or hinder microbial degradation pathways. Waste disposal should follow institutional guidelines for organic chemical waste, ensuring segregation from food, inorganic, or heavy-metal waste streams.
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