Carbonyldiimidazole
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Preferred IUPAC name
Di(1H-imidazol-1-yl)methanone | |
Other names
N,N'-carbonyldiimidazole
CDI Staab reagent | |
Identifiers | |
3D model (
JSmol ) |
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ChemSpider | |
ECHA InfoCard
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100.007.718 |
EC Number |
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PubChem CID
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UNII | |
CompTox Dashboard (EPA)
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Properties | |
C7H6N4O | |
Molar mass | 162.152 g·mol−1 |
Appearance | White fine powder |
Melting point | 119 °C (246 °F; 392 K) |
Reacts with water | |
Hazards | |
Occupational safety and health (OHS/OSH): | |
Main hazards
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Corrosive to some metals, Causes serious chemical burns upon skin or eye contact.
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GHS labelling: | |
Danger | |
H302, H314, H315, H319 | |
P260, P264, P270, P280, P301+P312, P301+P330+P331, P302+P352, P303+P361+P353, P304+P340, P305+P351+P338, P310, P321, P330, P332+P313, P337+P313, P362, P363, P405, P501 | |
Safety data sheet (SDS) | External MSDS |
Related compounds | |
Related compounds
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phosgene, imidazole |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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1,1'-Carbonyldiimidazole (CDI) is an organic compound with the molecular formula (C3H3N2)2CO. It is a white crystalline solid. It is often used for the coupling of amino acids for peptide synthesis and as a reagent in organic synthesis.
Preparation
CDI can be prepared straightforwardly by the reaction of
- 4 C3H4N2 + C(O)Cl2 → (C3H3N2)2CO + 2 [C3H3N2H2]Cl
In this conversion, the imidazole serves both as the nucleophile and the base. An alternative precursor 1-(trimethylsilyl)imidazole requires more preparative effort with the advantage that the coproduct trimethylsilyl chloride is volatile.
CDI hydrolyzes readily to give back imidazole:
- (C3H3N2)2CO + H2O → 2 C3H4N2 + CO2
The purity of CDI can be determined by the amount of CO2 that is formed upon hydrolysis.[3]
Use in synthesis
CDI is mainly employed to convert amines into amides, carbamates, ureas. It can also be used to convert alcohols into esters.[1]
Acid derivatives
The formation of amide is promoted by CDI. Although the reactivity of CDI is less than
In the realm of peptide synthesis, this product may be treated with an amine such as that found on an amino acid to release the imidazole group and couple the peptides. The side products, carbon dioxide and imidazole, are relatively innocuous.[5] Racemization of the amino acids also tends to be minimal, reflecting the mild reaction conditions.
CDI can also be used for
Similarly, an acid can be used in the place of an alcohol to form the
Another related reaction is the reaction of
Yet another reaction involves the acylation of triphenylalkelynephosphoranes.
- (C6H5)3P=CHR + R'-CO-Im → (C6H5)3P+-CHR-COR' + Im−
(C6H5)3P+-CHR-COR' + (C6H5)3P=CHR → (C6H5)3P=CR-COR' + (C6H5)3P+-CH2R
- (C6H5)3P=CHR + R'-CO-Im → (C6H5)3P+-CHR-COR' + Im−
These can undergo the Wittig reaction to form α,β unsaturated ketones or aldehydes.
The reagent can even undergo reaction with
A C-C acylation reaction can occur with a
Other reactions
The N-phenylimino derivative of CDI can be formed in a Wittig-like reaction with triphenylphosphine phenylimide.[1]
- OCIm2 + Ph3P=NPh → PhN=CIm2 + Ph3PO
CDI can act as a carbonyl equivalent in the formation of tetronic acids or pulvinones from hydroxyketones and diketones in basic conditions.[9]
An alcohol treated with at least 3 equivalents of an activated halide (such as allyl bromide or iodomethane) and CDI yields the corresponding halide with good yield. Bromination and iodination work best, though this reaction does not preserve the stereochemistry of the alcohol. In a similar context, CDI is often used in dehydration reactions.[3]
As CDI is an equivalent of phosgene, it can be used in similar reaction, however, with increased selectivity: it allows the synthesis of asymmetric bis alkyl carbonates[10]
See also
- Thiocarbonyldiimidazole (TCDI) the thiourea analogue
References
- ^ .
- ^ H.A. Staab and K. Wendel (1973). "1,1'-Carbonyldiimidazole". Organic Syntheses; Collected Volumes, vol. 5, p. 201.
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