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17455-13-9 - 18-Crown-6, 99% - 1,4,7,10,13,16-Hexaoxacyclooctadecane - A11249 - Alfa Aesar

A11249 18-Crown-6, 99%

Codice CAS
17455-13-9
Sinonimi
1,4,7,10,13,16-Hexaoxacyclooctadecane

Dimensioni Prezzo ($) Quantità Disponibilità
10g 40,80
50g 155,00
250g 613,00
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18-Crown-6, 99%

MDL
MFCD00005113
EINECS
241-473-5

Proprietà chimiche

Formula
C12H24O6
Peso formula
264.32
Punto di fusione
37-41°
Punto di ebollizione
116°/0.2mm
Punto di infiammabilità
109°(228°F)
Densità
1.175
Sensibilità
Hygroscopic
Solubilità
Soluble in water.

Applicazioni

18-Crown-6 is used as an efficient phase transfer catalyst and as a complexing agent with a variety of small cation. It is involved in the synthesis of diaryl ethers, diaryl thioethers, and diarylamines mediated by potassium fluoride-alumina and 18-crown-6. It facilitates the solubility of potassium permanganate in benzene, which is used for oxidizing the organic compounds. It is used to accelerate various substitution reactions as well as enhances the power of nucleophiles such as potassium acetate. It is utilized in the alkylation reactions in the presence of potassium carbonate, N-alkylation of glutarimide and succinimide with dimethylcarbonate. The complex formed by its reaction with potassium cyanide acts as a catalyst in the cyanosilylation of aldehydes, ketones and quinines with trimethylsilyl cyanide (TMSCN).

Note

Hygroscopic. Incompatible with strong oxidizing agents and strong acids.

Letteratura

Crown ether (see Appendix 2) mainly used to complex potassium ions. For a comprehensive study of solvent effects on complexation with K ions in a wide range of solvents, see: J. Org. Chem., 61, 5221 (1996).

Has been widely used in alkylation reactions with, e.g. K2CO3 as base:

Promotes methylation reactions with Dimethyl­ carbonate, A13104: Synthesis, 382 (1986). N-Alkylation of Glutarimide, L00968, and Succinimide, A13503: Bull. Soc. Chim. Fr., 227 (1992).

Enables KH to metallate aryl-substituted methanes directly: J. Am. Chem. Soc., 99, 4457 (1977). In the presence of KOH in DME, various arylmethanes, benzyl alcohols and aldehydes are oxidized to carboxylic acids by molecular oxygen: Tetrahedron Lett., 25, 4989 (1984).

Has been used with KF to enhance the reactivity of F- as a base or a nucleophile, e.g. to promote Michael additions in aprotic solvents: J. Chem. Soc., Chem. Commun., 237 (1977), the condensation of nitromethane with aldehydes: Tetrahedron Lett., 3219 (1978), and the transesterification of diaryl to dialkyl phosphonates: Synthesis, 409, 412 (1982).

Crown ether catalysis can be used in the reaction of KCN with alkyl halides to give nitriles: Tetrahedron Lett., 71 (1975), and for the preparation of acyl cyanides from acid chlorides: Tetrahedron Lett., 21, 2959 (1980). The 1:1 complex between 18-crown-6 and KCN has been used catalytically in the cyanosilylation of aldehydes, ketones and quinones with TMSCN; for examples, see: Org. Synth. Coll., 7, 517 (1990).

Flórez, A. I. G.; Ahn, D. S.; Gewinner, S.; Schöllkopf, W.; von Helden, G. IR spectroscopy of protonated leu-enkephalin and its 18-crown-6 complex embedded in helium droplets. 2015, 17 (34), 21902-21911.

Tzeng, B. C.; Chao, A. Single-Crystal-to-Single-Crystal Transformation and Solvochromic Luminescence of a Dinuclear Gold(I)-(Aza-[18] crown-6) dithiocarbamate Compound. 2015, 21 (5), 2083-2089.

Rischio GHS e dichiarazioni precauzionali

Dichiarazioni di rischio (UE): H302-H319-H313

Harmful if swallowed. Causes serious eye irritation. May be harmful in contact with skin.

Dichiarazioni precauzionali: P280-P264-P270-P305+P351+P338-P301+P312-P312-P337+P313-P330-P501a

Wear protective gloves/protective clothing/eye protection/face protection. Wash thoroughly after handling. Do not eat, drink or smoke when using this product. IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing. IF SWALLOWED: Call a POISON CENTER or doctor/physician if you feel unwell. If eye irritation persists: Get medical advice/attention. Rinse mouth. Dispose of contents/container in accordance with local/regional/national/international regulations.

Altri riferimenti

Merck
14,2602
Beilstein
1619616
Codice tariffe armonizzato
2932.99
TSCA
Yes
RTECS
MP4500000

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