02:214GFile Details4CH003/UM1: Fundamentals of...IntroductionPerhaps the cleanest method of conducting an oxidation is by catalyticoxidation, since this minimizes the problem of removal of unwanted by-products. However, the conditions used are often vigorous and require theuse of specialized equipment. By comparison, the product of a "chemical"oxidation may be more difficult to purify due to the presence of the reducedform of the oxidizing agent and potential "tars" that may arise from "over-oxidation". Because chemical oxidation can be carried out using conventionalequipment they are more popular.dissolving sodium or potassium dichromate in acid is a commonly usedoxidizing agent, being classed as a relatively powerful oxidant and havingwater soluble by-products (Cr III salts). Sulphuric acid is generally used if thematerial to be oxidized is water soluble and glacial acetic acid is used if it isChromic acid, prepared in-situ bynot.Alcohols are readily oxidized to carbonyl compounds by chromic acid.Secondary alcohols are oxidized to ketones and primary alcohols givealdehydes which are themselves in turn oxidized further to carboxylic acids.The purpose of this experiment is to demonstrate the oxidation ofcyclohexanol to cyclohexanone and improve your laboratory skills inpreparative organic chemistry.ProcedurePlace an aliquot of distilled water (30ml) into a 100ml round bottomed flask(placed on a cork ring). Carefully measure out 10ml of concentrated sulphuricacid in a dry measuring cylinder and slowly add it to the round bottomed flask.A little acid can be gently poured down a glass rod and then the flask swirledand the process repeated until all the acid has been added (NOTE: youshould never add water to concentrated acid, it should always be done theother way around and with care!).Place a thermometer into the mixture and cool the flask in a water bath untilthe temperature is below 200C. Remove the flask from the water bath andcarefully add cyclohexanol (10ml, 9.6g) to the acid mixture. Cyclohexanol isonly slightly soluble in water so you should observe two immiscible layers atthis point.Dissolve sodium dichromate dihydrate (10.5g) in water (5ml) in a 25ml conicalflask and, using a dropping pipette, add this solution carefully drop by drop tothe cyclohexanol/sulphuric acid mixture over about 30-40minutes. Swirl theflask vigorously during the addition process and maintain the temperature ofthe mixture in the round bottomed flask between 25-35°C during the additionby immersion of the flask in the cold water bath. If the dichromate solution isnot added slowly, a rapid rise in temperature will occur and the reaction willbecome violent.3When all the dichromate solution has been carefully added rinse the conicalflask with water (1ml) and then add this to the reaction mixture. Swirl the flasksteadily for a further 5 minutes when the temperature should be dropping,indicating that the reaction is complete. Add oxalic acid (~1g) to destroy the1 PreviousNext3000DashboardCalendarТо-doNotificationsInboxLO 02:214GFile Details4CH003/UM1: Fundamentals of...indicating that the reaction is complete. Add oxalic acid (~1g) to destroy theexcess oxidizing agent and then dilute the reaction mixture by the addition ofdistilled water (10ml).Connect the flask to a simple distillation assembly and distil the mixture untilabout 35ml has been collected in the receiver (conical flask). You couldspeed up the distillation by “lagging" still head with glass wool. When theapparatus has cooled sufficiently, pour the residue in the round bottomed flaskinto a 100ml of water contained in a beaker and place in the waste disposalbottle provided.Transfer the distillate in the conical flask to a separating funnel and add solidspatula of sodium chloride (~2g portions) to the separating funnel and shaketo dissolve. Continue the salt addition until no more salt will dissolve.Run off the lower aqueous layer into a waste beaker and then run the organiclayer into a clean 250ml conical flask and add drying agent (anhydrouscalcium chloride or anhydrous magnesium chloride), swirl the contents of theflask, stopper it and leave to dry for a few minutes whilst you reassemble thedistillation apparatus. Remove the drying agent by gravity filtration through afluted filter paper directly into a clean round bottomed flask. Add a pinch ofanti-bumping granules to the round bottomed flask and attach it to the stillhead fitted with a thermometer (0-360°C). Don't forget to apply a fine smearof silicon grease to any ground glass joint that is going to get hot.Distil the cyclohexanone slowly into a clean pre-weighed conical flask. Recordthe boiling range of the cyclohexanone, its appearance and the weightcollected.Calculate the yield of the product, record the infrared spectrum of the startingmaterial (cyclohexanol) and the cyclohexanone product.Assay the purity of the cyclohexanone by gas chromatography.Questions1. Write down the formula of the product obtained from the oxidation of 2-pentanol (pentan 2 0l What ie the name Of this proautt ketorO2. What is the formula of oxalic acid and what would you expect it to formOn Oxidation?3. What is the purpose of adding salt to the mixture in the separating44. Oxidation of ethanol gives ethanal which itself is then readily oxidizedto ethanoic acid. Given the boiling points below, suggest experimentalprocedures by which you could obtain high yields of:a) ethanal andb) ethanoic acid from the chromic acid oxidation of ethanol.1 PreviousNext >3000DashboardCalendarТо-doNotificationsInboxLO

4) a) Ethanal The given product can be produced by oxidation of ethanol and the reagent used is…

4CHO03/UM1: Fundamentals of... Introduction Perhaps the cleanest method of conducting an oxidation is by catalytic oxidation, since this minimizes the problem of removal of unwanted by- products. However, the conditions used are often vigorous and require the use of specialized equipment. By comparison, the product of a “chemical" oxidation may be more difficult to purify due to the presence of the reduced form of the oxidizing agent and potential "tars" that may arise from “over- oxidation". Because chemical oxidation can be carried out using conventional equipment they are more popular. dissolving sodium or potassium dichromate in acid is a commonly used oxidizing agent, being classed as a relatively powerful oxidant and having water soluble by-products (Cr III salts). Sulphuric acid is generally used if the material to be oxidized is water soluble and glacial acetic acid is used if it is Chromic acid, prepared in-situ by not. Alcohols are readily oxidized to carbonyl compounds by chromic acid. Secondary alcohols are oxidized to ketones and primary alcohols give aldehydes which are themselves in turn oxidized further to carboxylic acids. The purpose of this experiment is to demonstrate the oxidation of cyclohexanol to cyclohexanone and improve your laboratory skills in preparative organic chemistry. Procedure Place an aliquot of distilled water (30ml) into a 100ml round bottomed flask (placed on a cork ring). Carefully measure out 10ml of concentrated sulphuric acid in a dry measuring cylinder and slowly add it to the round bottomed flask.

10th Edition

ISBN:9781305957404

Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Publisher:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Chapter1: Chemical Foundations

Section: Chapter Questions

Problem 1RQ: Define and explain the differences between the following terms. a. law and theory b. theory and...