Recrystallising acetanilide

Recrystallising phenylacetamideThe aim of this experiment is to establish the close to suitable answer required for recrystallising acetanilide, and to exhibit the method actings of vacancy filtration and recrystallisation.Experimental mode (for selection of a suitable resolving)Four disregardrs dichloromethane, methylated sprits, petroleum ethoxyethane and piss were tested to see how appropriate they were for recrystallising acetanilide.Impure acetanilide (0.1g) was inserted into a small test tube and whilst continually shaking the test the solvent was added drop by drop.After 1cm3 of the solvent was added? the mixture was so modify till it was simmering using the piss supply for the organic solvents bath in the fume cupboard once approximately 1mL of solvent had been added.As the acetanilide was concluded the test tube was cooled to see whether recrystallisation occurred.The same method was iterate out for all four solvents.Experimental Method (for recrystallisation of acetanilide)Impure acetanilid (4g) was weighed out using a rough balance into a conelike flask (250mL).A suitable amount of the solvent from the previous method water (1mL) was used to wet the crystals.The mixture was then boiled gently, and more solvent was added until all the sold had dissolved.Using the filter wallpaper obtained from the pre-heated funnel the boiling solution was filtered. This was done into a pre-heated container so that rapid cooling as avoided.The flask containing the hot solvent was covered and al impressioned to cool slowly. When a marked amount of solid had formed and the solution had cooled packably, the solution was placed in an ice-bath to speed up the process.The filter paper was wet with the solvent then using vacuum filtration the crystals were separated from the rest of the solution.Using cold solvent (5mL approximately) the crystals were washed.The crystals were kept on the Bchner funnel until they were almost dry. The damp real was trans ferred to a labelled bewitch glass and then this was positioned into a vacuum oven of a set temperature lower than the melting of the pure solid.The dry purified carrefour was weighed and packaged into a labelled plastic bag.Why I chose water for the larger scale recrystallisationThis is because when cooling, water out of the four solvents dissolved all and the most crystals were formed. Also water is the most suitable solvent because it has the take up arcticity.The covalent bonding between an oxygen atom and two atoms of henry form a water corpuscle. Atoms sh atomic number 18 electrons between these covalent bonds. The sacramental manduction of these electrons is not equal in water as the hydrogen atoms reserve a weaker attraction to the electrons than the oxygen atoms. Hence the distribution of charge in water is asymmetrical. Molecules are known as polar when they return ends with corroborative and partially negative charges. The reason for wherefore water is able to dissolve a number is substances, is due to this signaling that enables water to separate polar solute molecules. pisss polarity makes gives it the property of being a good solvent.Water molecules surround polar or ionic compounds that enter water. One molecule of solute can be surrounded by many water molecules as the size of water is relatively small. The positive dipoles are attracted to negatively supercharged components of the solute and vice versa for the negative dipoles.The hydrogen bonds in water are ever so being formed and broken hence liquid water has a partially ordered structure.The spirited cohesiveness of water is due to the starchy hydrogen bonds and this also results in high surface tension. This is why water remains together as drops when on a non-soluble plane.Additional reasons for why water was the most suitable solventi. It was cheap to use water as the solventii. When the water was boiled at a temperature below the acetanilide melting point.iii. At sty le temperature the acetanilide appeared to put up low solubility when it was in water.iv. The water was also not toxic or flammable.v. When the acetanilide was heated to boiling in water it seemed to have high solubility.The main points in the procedure where the sample is lostThere are a number of ways in which the sample can be lost throughout the experimentOne of the reasons is whilst carrying out the practical many of our sample was spilt accidently by one of our neighbouring colleagues so our yield was less that what would have been expected. The sample whitethorn have been lost during the transfer stages i.e. when the sample was transferred to the conic flask some of the sample may have remained in the weigh boat as it is unlikely you can get a ascorbic acid% transfer. Further sample could have been lost when it was transferred from the conical flask to the Bchner funnel when washing the conical flask using distilled water. Furthermore, sample could have been lost by the t ransfer of sample from the Bchner funnel to the watch glass. Also when the crystals were transported into the glass plate as part of the sample may have got trapped to the pot and remained in the vacuum. When we used the filter paper to filter the acetanilide crystals some of the residue maybe have remained on the filter paper resulting in less sample. Why low boiling point solvent such as diethyl ether (BP 35C) or dichloromethane (BP 40C) are general les suitable for recrystallisation than higher boiling point solvents, such as water or ethanol, irrespective of their polarityOne of the technicians had said in the practical that methylene chloride has an occupation detonative limit (OEL)... Both diethyl ether and dichloromethane are the best solvents to consider as they are both flammable which is a safety hazard. Dichloromethane (DCM) is not as suitable because it evaporates more readily at room temperature (due to its low boiling point) which does not allow time for the crystals to dissolve. Also the debased compound would not have enough time to dissolve as well as the DCM would evaporate before hand. Why the solubility of paracetamol in water is several times higher than that of acetanilide by spirit at the structuresBecause the paracetamol contains an OH group hence it makes it more polar than acetanilide so it dissolves more readily in water which is also polar.ConclusionIn conclusion, water was found to be the most suitable solvent to dissolve acetanilide out of the four solvents in investigation. The yield of crystals formed is greater with a larger scale of production.