Acetanilida: síntese, recristalização e ponto de fusão

and today's experiment involves the synthesis and recrystallization and determination of the melting point of acetanilide the compound that was once used as an analgesic and antipyretic to antifebrin but was abandoned for causing the blockage of oxygen transport by hemoglobin this experiment was carried out to show is a life from a girl and a carboxylic acid derivative I had acetic anhydride 3. 3 grams of Melina already partially oxidized as seen by law I did not give staining girl at the beginning I wanted to show how recrystallization would help to purify the product Furthermore it turns Melina in 37 ml of hydrochloric acid one mole per liter which transforms the aniline in the year it into the balance aniline aniline is insoluble in water while the year it is not soluble I observed and the solubilization of aniline in the water then I added the acetic anhydride 3. 6 ml a little excess to the aniline and prepared a sodium acetate solution available in the form of trihydrate used 9.

14 g sodium acetate excess acetate Will result in a buffer and acetate is a stronger base than girl or aninium is stronger acid than acetic acid so the reaction between Mili Nest and acetate result in aniline and acetic acid the amount of acetate forms a buffer with a pH close to 5 and now releasing the aniline the electron pair is available to react with acetic anhydride through a substitution reaction a [ __ ] What happens quickly and form precipitates in the reaction medium this method is not valid for Mines because they are more basic and are not deprotonated by acetate the amines remain as ammonium which do not react by their substitution reactions to [ __ ] in this case use the schotten-baumann conditions that it occurs in a basic medium and in this reaction it is not necessary to heat after about 10 minutes. Turn off the stirring and filter acetanilide that precipitated from the medium I was another in bitner at reduced pressure washing with water to help the transfer The effect of solid and acid removal is this time in air with reduced pressure on. I dry the solid in an oven 2.

35 grams of crude acetanilide and to obtain the purified acetanilide, let's do a recrystallization I have already performed the recrystallization in the experiment with aspirin and almost well acetone acetanilide salt is insoluble in cold water and soluble in hot water and impurities organics can be removed in the hot filtration and heat it acetanilide and filter in a heated funnel with short cervix using pleated paper to increase the filtering surface of the paper and there and this filtration is faster than ordinary filtration avoiding precipitation of acetanilide during this process and let cool slowly and watch the formation of crystals of this process took over two hours and then left overnight and still carried the refrigerator to precipitate more acetanilide wire is solid in an ordinary situation let dry in the air and carried the oven Until the mass did not change, a sign that there is no longer only the mass obtained was 1. 90 grams, which gives a percentage yield 37 percent is the low value probably the aniline I used was very pure and absorbing the water from the environment this water contributes to the mass but does not contribute to the reaction and now I will determine the melting point of the solid obtained in is the first step is close the tip of a capillary using a flame careful never open the flame near volatile and flammable solvents such as ethyl ether and hexane and then press the open part of the capillary against the solid so that it enters the capillary and then I drop it through a hollow tube is long and notice that the solid that was at the top now goes to the bottom of the capillary in the experimental section of organic chemistry we have two melting point apparatus the principle is the same a heating block that is in contact with the capillary that inside a sample and a thermometer that records the temperature, one of them is digital and the other analogue I chose the analogue I fix the sample in the opening started heating by observing through the lens what happens with the sample slowly the temperature rises and I have chosen around two degrees centigrade per minute which is quite slow but will help us to visualize and determine with more certainty the final melting point and melting is the transition from solid state to good liquid and it is observed in the increase in the transparency of the material the sample starts melting at 116 degrees centigrade and ends at 118 degrees centigrade the literature value is between 113/115 for acetanilide which is even used as a calibration standard and point apparatus. melting so our apparatus has a difference of about two degrees centigrade with the standard not bad but it can improve So in this experiment we show the reaction and recrystallization and determination of the melting point of acetanilide with the melting point determination is an important resource for check the purity of materials that will be used in relation to or even in the preparation of drugs in Manipulation Pharmacies and if you liked the video, leave your like in write yourself.

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