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Last edited by CommonsDelinker (talk | contribs) 59 days ago. (Update) |
Comment: Wouldn't the formula be C20H20N4, as 4x4 carbons in pyrrole rings and 4 in methylene bridges? Graeme Bartlett (talk) 23:33, 19 August 2024 (UTC)- Comment: I suspect this has been drafted by a WP:LLM. It cites no sources, has errors such as calling acetone an aldehyde, and links to ChemSpider and Pubchem for entirely different compounds. The molecular formula is certainly wrong, as can be seen by noting that the drawing has >20 carbons Mike Turnbull (talk) 11:48, 20 August 2024 (UTC)
| Names | |
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| IUPAC name
5,10,15,20-Tetramethyl-25,26,27,28-tetraazacalix[4]pyrrole
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Other names
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| Identifiers | |
3D model (JSmol)
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| ChemSpider | |
PubChem CID
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| Properties | |
| C20H20N4 | |
| Molar mass | 316.40 g/mol |
| Appearance | White or off-white crystalline solid |
| Odor | Odorless |
| Density | 1.2 g/cm3 (approximate) |
| Melting point | 200–220 °C (392–428 °F; 473–493 K) |
| Soluble in organic solvents like chloroform, dichloromethane, acetone | |
| Vapor pressure | Negligible |
| Conjugate base | Calix[4]pyrrole anion |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Calix[4]pyrrole tetramer (Molecular formula: C₂₀H₂₀N₄) is an interesting compound in the field of supramolecular chemistry. This compound has a unique macrocyclic structure. The term "calix" comes from the Latin word for "cup" or "chalice." This reflects the bowl-like shape of the molecule. The "pyrrole" part of the name refers to the pyrrole rings that are the core structural units of this compound. Calix[4]pyrrole is made up of four pyrrole units. Pyrrole units are five-membered aromatic rings with nitrogen. The pyrrole units are connected by methylene bridges (-CH₂-) at the 2- and 5-positions of each ring. This arrangement of the pyrrole units forms a macrocyclic structure. The macrocyclic structure is a large ring or cycle that can host other molecules or ions in its central cavity. The calix[4]pyrrole has a bowl-like structure. This structure is not rigid. It can adapt to accommodate guest molecules, especially anions. The calix[4]pyrrole tetramer is flexible. This flexibility allows it to form stable complexes with various anionic species. This makes it important in the study of molecular recognition and host-guest chemistry.
Chemical properties
editMolecular formula and composition
editCalix[4]pyrrole tetramer is represented by the molecular formula C₂₀H₂₀N₄. This formula shows the composition of the compound. The compound consists of 16 carbon atoms, 20 hydrogen atoms, and 4 nitrogen atoms. The core structure of calix[4]pyrrole is formed by four pyrrole rings. Each pyrrole ring contains a nitrogen atom within a five-membered aromatic ring. The pyrrole units are linked by methylene bridges (-CH₂-). These bridges connect the 2- and 5-positions of each pyrrole ring. This results in a macrocyclic arrangement. The nitrogen atoms within the pyrrole rings are crucial. They play a key role in the compound's chemical behavior. This includes the compound's ability to interact with anions.
Physical properties
editThe Calix[4]pyrrole tetramer usually appears as a white or off-white crystalline solid. It can dissolve in various organic solvents, such as chloroform, dichloromethane, and acetone. This is because the macrocyclic structure is relatively non-polar, allowing it to dissolve in organic media. The compound is generally stable under normal lab conditions. Factors like light and moisture can affect its stability, potentially leading to slow decomposition or changes in its binding properties.
Anion binding
editCalix[4]pyrrole tetramer is known for its ability to bind anions, especially halides like chloride, bromide, and fluoride. This is because of its unique structure. The molecule has four pyrrole rings arranged in a macrocyclic fashion, creating a central cavity. This cavity is lined with hydrogen atoms from the pyrrole rings. These hydrogen atoms can form hydrogen bonds with anionic species, allowing the compound to bind anions. When an anion enters this cavity, it can be stabilized. This is because of multiple hydrogen bonds. The hydrogen bonds form between the anion and the hydrogen atoms of the pyrrole NH groups. The ability to selectively bind anions is an important feature of the calix[4]pyrrole tetramer. This makes it useful in various applications. These applications include molecular recognition, anion sensing, and environmental chemistry. It can be used for the detection and removal of harmful anions.
Synthesis
editSynthetic Methods
editThe synthesis of calix[4]pyrrole tetramer typically involves the acid-catalyzed condensation of pyrrole with a suitable aldehyde. The most common route to produce calix[4]pyrrole tetramer is as follows:
Starting Materials: The main ingredients for making calix[4]pyrrole tetramer are pyrrole and an aldehyde, such as acetone or formaldehyde. The choice of aldehyde can affect the structure and properties of the final product. Usually, acetone is used. It provides two carbon atoms to each methylene bridge that connects the pyrrole units.
Condensation Reaction: The synthesis starts with four pyrrole molecules and two parts of the aldehyde (like acetone). An acid, usually trifluoroacetic acid (TFA) or hydrochloric acid (HCl), helps this reaction. The reaction happens in an organic solvent like ethanol or methanol. It is done at room temperature or a bit higher.
Formation of Calix[4]pyrrole: The aldehyde reacts with the pyrrole units during the reaction. The pyrrole units link through methylene groups (-CH₂-). This results in the formation of the macrocyclic structure called calix[4]pyrrole. The reaction generally proceeds with good yields. The resulting macrocycle can be isolated by simple filtration or extraction techniques.
Purification: The crude calix[4]pyrrole tetramer is normally purified by recrystallization. The recrystallization is done using a suitable solvent, such as ethanol or methanol. Another option is to use column chromatography. This can help achieve a higher purity.
The overall reaction can be summarized as follows:
![{\displaystyle {\ce {4 Pyrrole + 2 Aldehyde ->[Acid Catalyst] Calix[4]pyrrole Tetramer}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/aa11b6fac7bb000a201d4927f4fcc5ba98bc5445)