Colocar 3g de acetanilida de en un matraz erlenmeyer de 125 ml.

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El informe debe contener los puntos de fusión de las dos muestras de nitroanilina p- con una discusión de las diferencias observadas en el comportamiento de punto de fusión. También se debe informar el porcentaje de rendimiento . los allí las muestras analizadas , con especial énfasis en las diferencias entre el patrón de puntos para cada muestra

place 3g of acetanilide in a 125 ml erlenmeyer flask. add about 5ml of concentrated sulfuric acid of the acetanilide. Dissolve most of the solid by swirling and swirling the mixture. Do not be concerned if a small, amount of undissolved solid remains . if will dissolve in later stages of this procedure. place the flask in an ice bath . Place 1,8 ml of concentrated nitric acid in a small flask, and add about 5ml of the concentrated sufuric acid to it. Caution: this is a hazardous mixture. this mixing should be done carefully in a hood. mix the acids thoroughly.

using a disposable capilary pipet, add small portions of the mixed acids to the cooled sulfuric acid solution of acetanilide. after each addition of acids, swirl the mixture thoroughly in the ice bath. Do not allow the flask to become warm to tje touch. after 20 minutes, including the time required for the addition of the nitric-sulfuric acid mixture, add 25 ml of an ice- water mixture to the reaction. a suspension of nitroacetanilide isomers will result. allow this mixture to stand for five minutes, with occasional stirring.

in order to hydrolyze the nitroacetanilides to the corresponding nitroanilines, the material in the flask will be heated, using the dilute sulfuric acid already present in the flask as the hydrolysing medium. Add a boiling stone to the erlenmeyer flask and heat the flask using a bunsen burner. a wire gauze will serve to disperse the burner flame. Heat the mixture to a gentle boil and continue heating for 15 minutes.

During the period the color of the mixture may darken, and the solid will dissolve. cool the flask in an ice bath, and when it is cool , add 25 ml of concentrated aqueous ammonium hydroxide, in 5 or 6 portions to the flask. this addition must be conducted in a hood because noxious fumes are evolved during the addition. Swirl the flask in the ice bath after each portion of ammonium hydroxide is added . the nitroaniline isomero will precipitate during this latter addition.

Collect the precipitated nitroanilies on a buchner funnel using vacuum filtration. wash the solid thoroughly with small portions of water. while continuing the vacuum, allow the solid to air-dry on the buchner funnel for several minutes

Scrape the solid material from the filter paper into a 25x10mm test tube and add sufficient ethanol of dissolve the solid when the ethanol is boiling. use the steam bath to heat the solution. when sufficient ethanol has been added to just dissolve the solid while the ethanol is boiling, allow the solution to cool. when the first crystals appear, place the test tube in a ice bath to bring the crystallization to completion. filter the crystals of p-nitroiniline by vacuum filtration using a hirsch funnel and a small filter flask. save the filtrate for a later tic analysis. wash the crystals with a minimum amount of cold ethanol and allow them to dry by drawing air though them on the filter for a few minutes. Save and dry a small sample of the crystals for a later determination of the melting point and a tic analysis .

few minutes. filter the charcoal from the solution by gravity, using a fluted filter paper. it probably will be necessary to repeat this gravity filtration an additional time. concentrate the filtrate to about one-third of its original volume on the steam bath. allow the solution to cool. when the first crystals appear, place the flask in a ice bath. after crystalization is complete, collect the crystals on a hirsch funnel by vacuum filtation. allow the crystals to air dry on the hirsch funnel by continuing to draw a vacuum on on them. when the crystals are dry , weigh them .determine the melting points of the two samples of crystals obtained before and after this final crystalization (literature value mp=149º) save a small sample of this purified p- nitroaniline for tic analysis. a labelec vial of the product should be submitted to the instructor.

For thin-layer chromatographic analysis , the samples Alli ( Filtrate form first crystallization , crude p -nitroaniline and purified Product y) are each dissolved in a few drops of ethanol . Each sample is spotted on a single tic plate which has been prepared tic From a microscope slides using silica gel G . Using chloroform as solvent ,develop the plaque and Compare the pattern of spots obtained for Each sample . The materials being studied are colored, so they should be visible . however, it may be Necessary to intensify the colors of the spots by Briefly exposing the tic palte to iodine vapors.

the report should contain the melting points of the two samples of p- nitroaniline with a discussion of the differences observed in melting point behavior . the percentage yield should also be reported. the the there samples analyzed, with particular emphasis on the differences between the pattern of spots for each sample