Bromination of Acetanilide

BROMINATION OF ACETANILIDE OBJECTIVEAim of the look into was too brominate ethanal to progress to p-bromoacetanilide.INTRODUCTIONAcetanilide is a chemical compound with the chemical formula of C6H5NH(COCH3). It is a cryst whollyine satisfying that is prepared by acetylation of analine and is astray apply in the dyestuff industry. This crystalline solid is an odourless solid chemical that has a flake or leaf like appearance. It is to a fault known as N phenylacetamide, acetanil or acetanilide. Its former trade call off was antifebrin. As menti unitaryd earlier acetanilide can be produced by reacting acetic anhydride with aniline.C6H5NH2 + (CH3CO)2O C6H5NHCOCH3 + CH3COOH (http//www. mendelset. com/articles/680/preparation-recrystallization-acetanilide) (regensburg. de/Fakultaeten/nat_Fak_IV/Organische_Chemie/Didaktik/Keusch/Grafik/box_brom_ar1. gif) The second figure illustrates the process used in the laboratory to form bromoacetanilide. Recrystallization is of key importance in the experiment because this method is used to stick the crystals. Recrystallization is a purification technique that removes impurities from a sample. An impure solid is set in a liquid for example water or ethanol. It is accordingly heated making the solid dissolve into the solvent.When the solvent cools back downward(a) again, the solid will precipitate egress of the source and leave the impurities behind, placid dissolved in the solvent. This method purifies the solid. Acetanilide has many uses in both pharmaceutical and manufacturing industry. It is used as a precursor in the subtraction of penicillin and other pharmaceuticals. Originally it was the first aniline discovered to posses analgesic and antipyretic properties. A. Cahn and P. Hepp introduced it in the medical field in 1886. It was later to be discontinue in the medical field because of its toxic nature that was believed to cause cyanosis in the patient.Through further research it was as well as discovered that acetanilide is metabolized in the form to form paracetamol which was responsible for the analgesic and antipyretic property. Acetanilide is also used as an inhibitor in hydrogen peroxide and is used to stabilize cellulose ester varnishes. It is also used in intermediation in rubber accelerator synthesis, dyes and dye intermediate synthesis and camphor synthesis. It is also used in the manufacture of sulfa drug drugs as it used for the production of 4-acetamidobenzenesulfonyl chloride, which is a key intermediate during this manufacture. system 4. g of acetanilide was placed in a 100cm3 cone-shaped flaskful. It was then dissolved by adding 20 cm3 of glacial acetic acid, which was measured out in a measuring cylinder. 7. 0 cm3 was dispensed directly into the conical flask by use of a burette in one portion. The flask was then swirled to mix the contents. It was then covered with a time glass and left in the fume hood for precisely 30 minutes long and swirled occasionally d uring the duration. Aqueous sodium hydrogen sulphite reply was added into the beaker until the red colour of the reactant disappeared this was to ensure that excess atomic subprogram 35 make during the reception was destruct.Feature Article Free-Radical BrominationThe lumps of solid found in the bottom of the flask were broken up to ensure no trapped bromine remained. As a precaution the first part of the experiment, which is outlined above, was carried out in a fumed press. The flask was then taken out of the cupboard and the solid was then filtered by sucking filtration using a Buchner displace and washed with distilled water (2x 25cm3 portions). As much water as assertable was removed from the solid by suction filtration then transferred to a 100cm3 conical flask.The crude solid was recrystallized by use of a minimum rule book of a mixture of ethanol and water in the ratio 2 1 at its boiling point. This mixture was added in portions using a steam bath as a heat source. The clear solution was then set aside to cool to near room temperature. The flask was cooled thoroughly in an ice/water bath afterwards the crystals were sedate by suction filtration using a Hirsch funnel. The crystals were then washed with approximately 1cm3 of ice-cold ethanol/water mixture, dried by suction filtration and the band and melting point ramble recorded.RESULTS Mass of empty advisement sauceboat 2. 25g Mass of empty weighing boat+crystals 5. 09g Mass of crystals 2. 8g Melting range 162 170C DISCUSSION Bromine is generally a toxic, corrosive and a unholy irritant to lung and eye tissues. Necessary precautions were taken during the experiment. One of the precautions taken was handling of the bromine solution in the reaction was done in a fumed cupboard. The excess bromine that was in the reaction was completely destroyed by adding aqueous sodium hydrogen sulphite solution.Protective gloves were worn to prevent the bromine liquid, ethanoic acid and sodium hydro gen sulphite from irritating the skin, as they are all skin irritants. The reaction that was carried out in the first part of the experiment is an electrophilic aromatic substitution. In the electrophilic aromatic substitution, an electrophile reacts with the benzene ring this result in an electrophile replacing hydrogen in one of the phenyl carbons such that the product of the reaction has the electrophile bonded to one of the phenyl carbon.We did not use aniline in this practical as it has carcinogenic properties instead we used acetic anyhidride which is a milder version. The other products formed in this reaction hydrogen bromide and can be gathered by hydrolizing(removing the hydrogen) to obtain the bromine. The percentage afford of the rection was calculated as follows Maas of products was 2. 84g hoagy mass of bromo acetanilide=214 0. 284/ 214 = 0. 00133 4. 5g of acetanilide used Molar mass = one hundred thirty-five 0. 45/134 = 0. 003 Yield 0. 00133/0. 003x 100 = 44. 3% yie ld.As clearly illustrated the percentage yield is less than a 100% this could be due to a number of reasons like some of the solid might have been lost during the suction or while washing the crystals with the water and ethanol mixture the weighing scales could also have been inaccurate. CONCLUSION Better practical methods are need during the experiment to ensure a 100% yield. REFERENCES http//www. mendelset. com/articles/680/preparation-recrystallization-acetanilide regensburg. de/Fakultaeten/nat_Fak_IV/Organische_Chemie/Didaktik/Keusch/Grafik/box_brom_ar1. gif)