Iodoform [PDF]

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PREPARATION OF IODOFORM Make a short abstract of these directions to use as a guide while doing the work. Make a habit or preparing such abstract for all experiments. Directions. In a 500cc Florence flask place 10g of iodine and pour onto this 10g of aceton. Add in small portions, and with constant shaking, as much as is needed of a solution made up of 200cc of 8N sodium hydroxide solution and 80cc of water. If the flask become hot to the hand, cool it at once wit running water. When sufficient sodium hydroxide solution has been added set the flask aside. No free iodine should be present at this time, nor any suggestion of brown color in the liquid. Look carefully on the bottom of the flask for unattacked iodine. After 5 minutes collect the yellow precipitate, using the small Buchner funnel. Place filtrate at once in bottle labeled “ Iodoform filtrate.” Wash the solid on the funnel whit a little water. The compound is then to be dissolved in the smallest possible quantity of hot ethyl alcohol as follows. Put the iodoform in the small flask arranged for refluxing ( see Expt.19 ). Pour a few cc or alcohol down the condenser ( no flames within 6 ft ), and warm on electric hotplate or steam-bath, shaking the flask at times. When the mix is warm add a little more alcohol, then wait till it becomes hot to see whether enough has been added to dissolve all ( there will always be a few shreds of filter paper, etc. which should not be mistaken for iodoform ). Do not heat longer than necessary and avoid actual boiling if possible. When enough solvent ( about 40cc ) has been added to dissolve all the iodoform at the boiling point of the solution, add about 2cc additional sovent, then filter the hot solution through a fluted filter paper, using a funnel previously warmed over the hot-plate or stean-bath.



Caution-do not inhale the vapor of solution. Cover the filtered solution and set aside to cool slowly. In 15 minutes add about 25cc of water, meanwhile stirring vigorously to completely precipitate the iodoform, the filter with the Buchner funnel. Wash the crystals on the funnel with a few drops of cold alcohol (cut off suction during the washing ). Remove the crystals from the filter paper and spread the on a fresh, dry piece of filter paper. The best way to remove paper, etc from Buchner funnel is to hold it over a clean filter paper and blow gently through the stem. The end of the funnel stem should first be washed so that no chemicals can get on the lips. Any crystals remaining in the funnel are removed whit knife or spatula. The crystals are to be placed in the desiccators. Place an identification slip in the desiccators. Product in course of preparation should always be labeled; do not rely on the memory. The bottom of desiccators should contain granules of calcium chloride to depth of about 15mm. the melting point and weight of the preparation will be determinate after it is dry, at the next laboratory period. For directions for melting point determinations Expt.4. submit the product in a sample bottle, properly labeled ( see Expt. 18, p 46 ).