Organic 2 Review Problem 90

Organic 2 Review Problem 90 - to a water-condenser C (Fig....

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74 PRACTICAL ORGANIC CHEMISTRY To prepare pure acetic acid (glacial acetic acid), the crude aqueous product is converted into the sodium salt, the latter dehydrated by fusionf and then heated with concentrated sulphuric acid: anhydrous acetic acid, b.p. 118°, distils over. Only the preparation of aqueous acetic acid and of crystalline copper acetate is described below. Technically, acetaldehyde is mainly made by the oxidation of ethylene using a CuCl 2 /PdCl 2 catalyst system. Although some acetic acid is still prepared by the catalytic oxidation of acetaldehyde, the main process is the catalytic oxidation of paraffins, usually w-butane. Acetaldehyde, CH 3 CHO, in Aqueous Solution. Required: Ethanol, 40 ml.; sodium dichromate, 50 g.; sul- phuric acid, 17 ml. Fit a 500 ml. bolt-head flask F with a well-fitting cork which is free from flaws, and which carries a dropping-funnel D and a delivery tube (or " knee-tube") T, the latter being connected
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Unformatted text preview: to a water-condenser C (Fig. 52). Attach an adaptor A to the lower end of the condenser. (Alternatively, use a ground-glass flask (Fig. 22(A), p. 43) with a distillation-head (Fig. 22(F)): the dropping-funnel can be fitted into the distillation-head, the side-arm of which is connected to a condenser as in Fig. 23(0), p. 45.) Place 50 ml. of water in the flask F, and then add slowly with shaking 17 ml. (31-5 g.) of concentrated sulphuric acid: finally add some fragments of unglazed porcelain, and replace the flask. Dissolve 50 g. of coarsely crushed sodium dichromate* in * Sodium dichromate is used instead of the potassium salt because it is far more soluble in water, and is not precipitated from its aqueous solution by addition of the ethanol. It is also cheaper than the potassium salt, but has the disadvantage of being deliquescent. t Cf. p. 117....
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This note was uploaded on 09/19/2011 for the course CHM 2211 taught by Professor Castalleano during the Fall '06 term at University of Florida.

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