Paraphrase a Reports and Solve Past Exams Papers - Coursework Example

? PARAPHRASED PAPERS by Preparation of 2-Chloro-2-methylpropaneAim: The experiment was used to prepare 2-Chloro-2-methylpropane Method: 47.74ml of 2-Methyl-2-propanol (t- butanol) was mixed with 125 ml of HCl in a separating funnel. The stopper was inserted after swirling the mixture for 60 seconds. The pressure was released by inverting the funnel. The mixture was then shaken until a double layer was seen. The top layer was washed with 50ml of brine before adding sodium bicarbonate (50ml). The funnel was shaken gently until no effervescence was observed. The top organic layer was washed with water followed by brine in the funnel. Both brine and water ought to be 40 ml. The top organic layer was then transferred into a conical flask before adding anhydrous magnesium sulphate. The mixture was swirled and filtrated in a round bottomed flask. The final product was then distilled in a pre-weighed flask that is ice-cold. The weight and melting point was then measured and recorded. In addition the sample of the IR spectra was carried out. Results: Boiling point: 50°C-52°C Volume: Number of moles: 0.5 mol R.M.M: 74 g/Mol Density: 0.775 g/Mol Mass: 74 0. 5=37 g Volume: Mass/density = 47. 74 ml HCl: Concentration 12 M Number of moles: 1.5 mol Volume=Number of mole / concentration . = = 0.125 L =125Ml. The weight of flask=74. 64 g The weight of flask + sample=92. 36 g Sample’s weight=92. 36-74.64= 17.72 g Theoretical yield = 0.5 x 92.567 =46. 28 g Percentage yield: 17.72 x100/46.28 =38. 3 % Discussion: At room temperature 2-Chloro-2-methylpropane was a colorless liquid organic compound. 2-Chloro-2-methylpropane was slightly soluble and spontaneously solvolysed when dissolved in water. 2-Chloro-2-methylpropane was volatile and highly flammable. The compound was normally used to carry out reactions of nucleophillic substitution to produce various substances such as alcohol and alkoxide salts. The experiment successfully produced 2-Chloro-2-methylpropane. SN1 was the mechanism that formed 2-Chloro-2-methylpropane. The t-butyl was used as a base andnucleophile that attacked proton from the solution containing hydronium ion. This was attributed to the ability of t-butyl to accept protons from hydronium ion. For stability. The bondage existing between oxygen and carbon broke hydrolytically. The breakage formed carbocation and was used as electrophille: species’ lacking electrons. Absence of electrons made chloride ions to attack carbocation hence molecule stability. Carbocation assumed role of Lewis acid that welcomed electron from Cl- forming t-butyl chloride. It was then synthesized through SN1. http://1chemistry.blogspot.co.uk/2011/06/synthesis-of-tert-butyl-chloride.html The excess HCL was neutralized by sodium bicarbonate which gave misleading results. The IR spectra are illustrated below: 2: Hydrobromination of trans-stilbene practical. Aim: When the electrophilic species are added to an alkene, the procedure were allowed prepare various functional group. The below reaction, N-bromosuccinimide acted as an electrophilic species which facilitated the addition of HOBr to the double bond. Method: A mixture of 60 ml of dimethylsulfoxide, 1 cm3, and 56 mmol of water, and 3.6 g, 20 mmol of trans-stilbene was transferred to a flask that is round bottomed (100ml). The solution then stirred hard at room temperature. For over ten minutes, 7.1 g with 40 mmol of N-bromosuccinimide was added portion by portion. The solution was left for twenty minutes to mix accordingly. The reaction was transferred to a separating funnel. The separating funnel (200ml) had iced water. Using 4 x 40 ml of diethyl ether after the ice is completely melted, the solution was extracted. Subsequently, the extract fron ethereal was drained with 50 ml of water and brine. The extract was thereafter dried by using MgSO4. On the bath the rotary evaporator concentrated the solutions. On the surface of the solution, white crystals were formed. Further crystallization occurred by cooling it in an ice bath. Buchner funnel was then used to filter the solution. The crystals were later dried. Results. The theoretical melting point: 85.0 degree Celsius Melting point: 83 degree Celsius Weight of flask: 8.57g Sample weight + flask 13.07g Mass of trans-stilbene: 3.6g Number of mol for trans-stilbene 0.02 mol Rmm for trans-stilbene 180g/mol Mol of N-bromosuccinimide 0.04. Mass: N-bromosuccinimide=7.1g Rmm: N-bromosuccinimide=178g/mol The reactant that was confined was trans-stilbene Rmm: 2-bromo-1, 2-diphenylethanol= 277g/mol Literature yield: 0.02 x 277 =5.53 Percentage yield 4.5/5.53*100 =81.4 % IR interpretation: 3399.95,3028.65 cm-1 O-H stretch (3600-3000) cm-1 1584.93, 1496.00,1453.98 cm-1 Aromatic C=C stretch of benzene is 1600- 1455 cm-1 995.20,914.33,817.56,759.30,697.99cm-1 Aromatic C-H stretch 1000-690 cm-1 Interpretation of NMR. 7-8 Protons of Benzene 2-5 ROH variable Alcohol Discussion. Experiment was a success. 81 percent yields implied the yield was alright. Errors erupted due to spillage and untimely recording of boiling and melting point. The yield would have been much greater if the errors were avoided. The product had double chiral centre, this is according to 2^n rule, where the stereoisomer formed need to be four. However, only a single pair was formed. Each of the pair existed as enantiomers pair this was attributed to antisterioselectivity. Additionally, only a single diastereoismer was formed because the Bromo from N-bromosuccinimide was in a competition with the source of OH for the reaction with trans-stilbene. The intermediate of the bridge was formed by Br so that the double bond (2S) can be opened. Then the reaction of OH occurred at IR. This was the stable formula than the combination of IS and 2R. Obtained data from melting point, NMR and IR showed that the product was Eritrea-2-Bromo-1, 2-diphenylethanol in a pure state. The melting point range was good when compared to the literature data. 3: Isolating (S) from Caraway Seeds. Experiment Aim: The experiment isolated (S) Carvone and Caraway Seeds. Method: 25g of crushed caraway seed was added to 250 ml distilled water in a round bottomed Flask. Using boiling process the mixture was distilled. Pour 80 ml of the mixture into a 250ml separating funnel. 5g of NaCl was added and then stirred until it dissolved. To extract and dry the aqueous mixture, dichloromethane (2 x 20ml) and MgSO4 was used respectively. The mixture was then dried by passing it over MgSO4. Filtration and evaporation of dichloromethane was done on a rotary evaporator at room temperature. Then determine and record the product’s mass and its infrared spectrum. .Results: Results: Mass: (S) Carvone after being evaporated. =0.4g Flask+Base =135.90g Product =0.41g Optical Rotation: (S) Carvone is +.2 (R) Carvone -.68 (S) Carvone Optical Activity, its theoretical value: = 54 sigma D= a/C*L C (Concentration) in g/mol. L (Path Length) in dm Optical Rotation: (S) Carvone=+.2/0.049*25/100 =16.68 (R) Carvone: -.68/ (5/100*25/100) =-54.4 Calculation of Optical Purity: Obtained/Literature =10016.68/54 =30.88 per cent IR spectra interpretation: Peak Freq,cm-1 Functional group 3084.76 3000-2900 Alkenes = (C-H) stretch 2923.38 2900-2700 Ketone/ alkyl (C-C) (C-H) Stretch 1671.57 1950-1600 Carbonyls (C=O) stretch 892.88 670-1010 Alkene (C-H) (S) 9 carbon extraction spectra. 3D structure of (S) -Carvone: 6.5g 20 mmol 278.17 g/Mol 180.256 g/mol 177.99g/mol moles = (g/mol) Discussion and conclusion. The two images and enantiomers were formed. (R) Carvone smelt as spearmint as (S) Carvone smelt as Caraway. The experiments aim determined the two enantiomers optical rotation. The computations of (S) Carvone indicated the product to be thirty per cent pure. This was attributed to contaminated equipment in addition to experimental and human errors. Consequently, S- Carbon can also be termed as Dextro-, d- while R-Carbon can also be referred to as Levi-, I-.. . Read More