méthodes de purification

[papillon de mer]

Bonjour,

svp, j'avais une question à propos la purification de l'aniline, est que je peux faire la distillation ?
-----

[invitef5d8180a]

Bonjour,

svp, j'avais une question à propos la purification de l'aniline, est que je peux faire la distillation ?

Bonjour,
Oui, sous pression réduite ça se distille.

[Lycaon]

s'il s'agit d'éliminer les produits d'oxydation qui la colorent, le noir de carbone est efficace

[invitef5d8180a]

Je te conseille aussi la bible de la purif de produit commerciaux: "Purification of Laboratory Chemicals"
Extrait:
"Aniline [62-53-31 M 93.1, f -6.0°, b 68.3/10mm7 184.4O/760mm, d 1.0220, n 1.585, nZs 1.5832, pK2’ 4.60. Aniline is hygroscopic. It can be dried with KOH or CaH2, and distd at reduced pressure. Treatment with stannous chloride removes sulfur-containing impurities, reducing the tendency to become coloured by aerial oxidn. Can be crystd from Et20 at low temps. More extensive purifications involve preparation of derivatives, such as the double salt of aniline hydrochloride and cuprous chloride or zinc chloride, or N-acetylaniline (m 114O) which can be recrystd from water.
Recrystd aniline was dropped slowly into an aqueous soln of recrystd oxalic acid. Aniline oxalate was filtered off, washed several times with water and recrystd three times from 95% EtOH. Treatment with satd Na2C03 soln, regenerated aniline which was distd from the soh, dried and redistd under reduced pressure [KnowlesInd Eng Chem 12 881 19201.
After refluxing with 10%acetone for lOh, aniline was acidified with HCl (Congo Red as indicator) and extracted with Et20 until colourless. The hydrochloride was purified by repeated crystn before aniline was liberated by addition of alkali, then dried with solid KOH, and distd. The product was sulfur-free and remained colourless in air [Hantzsch and Freese Chem Ber 27 2529,2966 18941.
Non-basic materials, including nitro compounds were removed from aniline in 40% H2SO4 by passing steam through the soln for lh. Pellets of KOH were added to liberate the aniline which was steam distd, dried with KOH, distd twice from zinc dust at 2Omm, dried with freshly prepared BaO, and finally distd from BaO in an all- glass apparatus [Few and Smith J Chem Soc 753 19491. Aniline is absorbed by skin and is TOXIC"

[A voir en vidéo sur Futura]

[papillon de mer]

merci beaucoup pour votre réponses : CN_is_Chuck_Norris et Lycaon
pouvez vous me reexpliquer la purification par le noir de carbone

et merci d'avance

[invite2313209787891133]

Bonjour

Le noir de carbone est une variété de charbon actif. Il contient des pores dont la taille piège préférentiellement certaines molécules, ce qui permet d'améliorer la pureté du produit. Concrètement il suffit de mélanger une cuiller de charbon, de mélanger, de laisser reposer quelques minutes et de filtrer.