Clean surfaces, alcohol reactions

Clean single-crystal surface, 15 31 Clean surfaces, alcohol reactions, 29 37-38 Clear Air Act of 1970, 24 59, 62 Cleavage surfaces, dislocations on, 19 331-333 ClOj, ESR of, 22 309... 

Reactions alcohols, 29 36-49 adsorption, 29 36-37 clean surfaces, 29 37-38 ethanol oxidation, 29 44—48 methanol oxidation, 29 38-44 oxidation on copper and silver, 29 38-48 oxidation reaction, silver, 29 48-49 base-catalyzed, of hydrocarbons, 12 117 free radical mechanism in, of hydrogen peroxide, 4 343... 

Methanol and ethanol react strongly with Na and K. When the carbon chain of the alcohol extends the intensity of the reaction decreases. Generally, potassium is preferred for the long-chained alcohol reactions. Some metals, such as magnesium and aluminum can react with alcohols to produce H2 gas when their oxide layers are cleaned from their surfaces. 

Method 1. Place 11 5 g, of clean metallic sodium (compare Section III,7, Note 1), cut into small pieces, into a dry 1 litre round-bottomed fiask fitted with a 25 cm. double surface reflux condenser. Introduce 250 ml. of absolute, but preferably super dry (see Section 11,47, 5) ethyl alcohol all at once. A vigorous reaction ensues if the condenser tends to become flooded with alcohol, cool the flask either by surrounding it with a wet towel or by directing the waste water from the condenser upon... 

Place 10 g. of clean sodium (cut into small pieces) in a 500 ml. round bottomed flask fitted with a double surface reflux condenser. Introduce 100 g. (127 ml.) of absolute ethyl alcohol and allow the reaction to proceed as vigorously as possible if the alcohol tends to flood the condenser, cool the flask momentarily with a wet towel or by a stream of cold water. When all the sodium has reacted, add 40 g. of pure phenol. Distil ofif the... 

In a 2 litre round-bottomed flask, fitted with a double surface reflux condenser, place 11-5 g. of clean sodium. Add 250 ml. of absolute alcohol in one portion if the reaction is unduly vigorous, immerse the flask momentarily in ice. When all the sodium has reacted, add 80 g. (76 ml.) of ethyl malonate (Section 111,153), followed by a solution of 30 g. of dry urea in 250 ml. of hot (ca. 70°) absolute alcohol. Shake the mixture well, fit a calcium chloride (or cotton wool) guard tube to the top... 

Ethyl phenylethylmalonate. In a dry 500 ml. round-bottomed flask, fitted with a reflux condenser and guard tube, prepare a solution of sodium ethoxide from 7 0 g. of clean sodium and 150 ml. of super dry ethyl alcohol in the usual manner add 1 5 ml. of pure ethyl acetate (dried over anhydrous calcium sulphate) to the solution at 60° and maintain this temperature for 30 minutes. Meanwhile equip a 1 litre threenecked flask with a dropping funnel, a mercury-sealed mechanical stirrer and a double surface reflux condenser the apparatus must be perfectly dry and guard tubes should be inserted in the funnel and condenser respectively. Place a mixture of 74 g. of ethyl phenylmalonate and 60 g. of ethyl iodide in the flask. Heat the apparatus in a bath at 80° and add the sodium ethoxide solution, with stirring, at such a rate that a drop of the reaction mixture when mixed with a drop of phenolphthalein indieator is never more than faintly pink. The addition occupies 2-2 -5 hoius continue the stirring for a fiuther 1 hour at 80°. Allow the flask to cool, equip it for distillation under reduced pressure (water pump) and distil off the alcohol. Add 100 ml. of water to the residue in the flask and extract the ester with three 100 ml. portions of benzene. Dry the combined extracts with anhydrous magnesium sulphate, distil off the benzene at atmospheric pressure and the residue under diminished pressure. C ollect the ethyl phenylethylmalonate at 159-160°/8 mm. The yield is 72 g. 

The sodium ethoxide solution is conveniently prepared as follows. Place 46 g. of clean sodium (Section 111,7, Note 7) in a 2 litre round-bottomed flask provided with a 25 cm. double surface condenser. The apparatus must be perfectly dry. Cool the flask in a bath of crushed ice. Add 800 ml. of super-dry ethyl alcohol in one operation. A vigorous reaction will ensue, but it will remain under control. When the initial reaction is over, remove the ice bath and allow the residual sodium to react. If small quantities of sodium remain, warm the flask on a water bath until solution is complete. 

Most aliphatic amines and alcohols are considered to be nonelectroactive. The reason for this is that the product of the oxidation adsorbs to the electrode surface, fouling the electrode. Therefore, most reactions of these compounds at noble metal electrodes have been transient and not amenable to direct amperometric detection. In voltammetry experiments, electrodes are cleaned between experiments by electrochemical or chemical treatment to restore the electrode response. 

For the less electropositive metals, direct reaction between the bulk metal and alcohols does not readily occur. However, for the Group II, III and lanthanide metals, reaction will occur in the presence of a catalyst.12,15 Typical catalysts are iodine or a mercury(II) halide and their action is believed to be either in cleaning the metal surface or in forming intermediate halide derivatives which then undergo facile reaction with the alcohol (equation 2).12... 

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