Preparation of Cyclohexanol

Introduction Cyclohexanol is mainly utilize in the production of caprolactam and adipic pane that is a raw material of nylon 6 (Zhang, et al, 2002). Cyclohexanol can be produce by several methods, which include the oxidization of cyclohexane, the hydration of cyclohexene, or the hydrogenation of phenol (Zhang, et al, 2002). Problem with oxidation of cyclohexene is poor selectivity, extremely large recycles and explosion hazards. (Suresh, Sridhar, Potter, 1988). The purpose of this investigate was to deductive reasoning cyclohexanol by hydration of cyclohexene using concentrated sulfuric acid as an bitter gas.In hydration reaction, C=C B bond is re practiced by hydroxyl comp both (Hornback, 2006). Overall reaction (McFadden, 2012) In the first step, the mixture of piss, concentrated sulphuric acid, and cyclohexene was shaken sprucely until it became a homogenous radical. Followed by, the addition of weewee, and the distillation attend lead to the hydrolysis of the alke ne. Finally, addition of diethyl ether to the mixture so distillation took place to be purified and to acquire the final product, cyclohexanol (McFadden, 2012).Diethyl ether was apply to extract inebriantic beverage from salt- weewee mixture because diethyl ethers solvability in water is lower than cyclohexanol which helps remove alcohol from the salt-water mixture (Merzougui, A, et al. , 2011). (McFadden, 2012) Cyclohexene is added to water-acid outcome, which organize two liquid phases were receivable to insolubility of cyclohexene in water-acid solution. It is very distinguished that mixture is mixed well to behave a homogeneous solution and allow reaction to complete. Cyclohexene was reacted with water and with sulfuric acid to form protonated cyclohexanol and cyclohexyl hydrogen sulfate.Protonated cyclohexanol and cyclohexyl hydrogen sulfate are soluble in water-acid solution (McFadden, 2012). When this mixture is heated, cyclohexyl hydrogen sulfate converts to protona ted cyclohexanol which is equilibrium with cyclohexanol (McFadden, 2012). Moreover, distillation proficiency is used to separate components of a liquid mixture, where liquid is boiled to go a counsel and then condensed back into liquid called distillate. Distillate components are get toge thered with a lowest-boiling excite to highest-boiling bill.In this experiment, distillation is used to separate the organic compound from sulphuric acid solution azeotrope of cyclohexanol and water is formed as distillate, it be arrays contains both(prenominal) cyclohexene components. Azeotrope has a fix boiling point like a arrant(a) compound. Cyclohexanol is considerably soluble in water, so poor founder is judge (McFadden, 2012). Addition of sodium chloride to distillate solution improves the final product event because it reduces the solubility of organic compound, and extracts cyclohexanol from sedimentary phase. It is due to salts higher(prenominal) solubility than organic compoun d.Also, anhydrous thousand carbonate is used to souse water and to neutralize any trace of acid. During distillation of vestal cyclohexanol, to the highest degree of the product should be collected as temperature reaches 161? C (Weast, 1988). This experiment also introduces determination of the refractive forefinger it is one of the most convenient methods used to determine purity of liquid. It is a ratio of the sine of the angle formed when light ray is bent when passing from an air medium into a liquid medium in other words it is a ratios of the rush along of light in a vacuum to the speed of light in the liquid medium.Refrective index (n) = C_vaccume/V_medium (McFadden, 2012). At 20C, the expected refractive index of cyclohexanol is 1. 4641 (Weast, 1988). Procedure The experiment was done in two parts. Part-A was hydration of the alkene, and Part-B was isolation and civilization of the cyclohexanol. To perform hydration of alkene, 7. 0mL of water and then 14mL of concentra ted sulphuric acid were added to a 125mL Erlenmeyer flaskful. later that, flask was placed in ice-bath until it was cold to touch. 16. 4g of cyclohexene was added to weighed 250mL round-bottom flask.In the similar round-bottom flask, the chilled water-acid mixture was added. In order to mix the solution, the flask was vigorously shaken for 20 minutes. While shaking, regularly s croakper was released to hold open any build-up of vapour pres accredited. After flask was vented and allowed it to stand without disturbing for round 5 minutes. Because two distinct layers appeared, continued shaking for extra 10 minutes until solution was homogeneous. Next, an additional 120mL of distilled water were added in homogeneous solution with addition of 3 boiling chips.The same round-bottom flask was then set onto a distillation apparatus, and started distillation. Distillate was collected into an 125mL Erlenmeyer flask, and boiling point diverge of azeotrope was noted. Subsequently, 25g NaC l was dissolved to the distillate, but not all salt was dissolved. After that, flask was covered with parafilm (McFadden, 2012). In the next lab, distillate mixture was transferred to a separatory funnel. Distillation receiver flask was washed by 20mL diethyl ether, that diethyl ether was then transferred into the separatory funnel.Mixture was allowed to delayer for 3 minutes. Afterwards, bottom sedimentary layer was drained into a aqueous waste beaker and top ether layer was transferred in an another 50mL Erlenmeyer flask which contained 3g of anhydrous potassium carbonate, swirled and allowed the mixture to stand for 15 minutes. Next, no potassium carbonate but only liquid mixture was transferred to round-bottom flask for the distillation. Diethyl ether and cyclohexene were distilled and collected into a flask until it reached 120C, and later discarded in an organic waste.As temperature reached 120C, a change, dry and pre-weighed flask was replaced to collect final product, cycl ohexanol. As soon as flask was replaced, cold water was turned-off and hot water was turned on. Continued to distil until there was no liquid in the distillation flask, and boiling chips started to change colour. Small get along of residue was kept in distillation flask to prevent it from breaking. Finally, cyclohexanol was leaden and from small sample the refractive index was determined (McFadden, 2012). Result nitty-gritty of cyclohexene used = 16. 40g = 16. 40g of C_6 H_10? 1/(82. 143 g/mol)=0. 9965=0. 1997mol of C_6 H_10 Limiting reagent is Cyclohexene Bp range of azeotrope mixture 85-95. 4C Literature bp range of azeotrope mixture 97. 8C mutation 53rd paginate D-16 Bp range of diethyl ether 34. 6-41. 6CLiterature bp range of diethyl ether 34. 51C edition 53rd page Bp range of cyclohexene 82. 8-90C Literature bp range of cyclohexene 82-98C edition 53rd page C-259 Bp range of pure cyclohexanol 157-161. 0C Literature bp range of cyclohexanol 161. 1C edition 53rd page C-257 met ric weight unit of pure cyclohexanol = 7. 1g Percent yield = (actual yield (g))/(theoretical yield (g))? 00%=7. 1g/20. 00g? nose candy%=35. 5% Theoretical yield= (0. 1997mol of C_6 H_10)/? (1 mol of C_6 H_12 O)/(1 mol of C_6 H_10 )? (100. 158 g)/(1 mol of C_6 H_12 O)=20. 00g Refrective index of pure cyclohexanol raw 1. 4643 at 21. 2C Corrected 1. 4658 at 20C Correcting refractive index n_D20=n_D21+0. 00045C(-1)? (21. 2-20C) =n_D21+0. 00045C(-1)? (1. 2C) =1. 4643+0. 00054 =1. 46484=1. 4648 Refractive Percent yield wrongdoing ((1. 4648-1. 4641))/1. 4641? 100%=0. 05% Literature refrective index of cyclohexanol 1. 4641 at 20C Edition of CRC 53rd page C-257 DiscussionBefore reaching a concrete conclusion, it is very important to interpret the result that was obtained in this experiment. In this experiment, cyclohexene was hydrated to produce cyclohexanol because the school hydration of cyclohexene is very slow, concentrated sulphuric acid as an acidic catalyst is used to speed up the reaction (McFadden, 2012). When cyclohexene was reacted with water and concentrated sulphuric acid, dark homogenous solution was formed from colourless heterogeneous mixture. The reaction was cyclohexene ? protonated cyclohexanol + cyclohexyl hydrogen sulfate. Both of hese products were soluble in water-acid solution, therefore reaction could go to completion (McFadden, 2012). Moreover, azeotrope of cyclohexanol and water was a positive azeotrope which heart boiling point of azeotrope was less than the boiling point of cyclohexanol and water. Moreover, distillation process can prevent side reactions and by removing the products it shifts equilibrium on right hand side to increase percent yield however, it is not enough to improve percent yield. Cyclohexanol is soluble in water so addition of NaCl forces cyclohexanol to leave aqueous phase into organic phase.By reducing its solubility in water, NaCl molecules were holding water molecules. It is due to NaCls stronger attraction to w ater than cyclohexanol solubility of NaCl in water is 360g/L, and solubility of cyclohexanol in water is 36. 0g/L (Weast, 1988). It is a great way to separate azeotrope into different components. However, enough salt is necessary to make solution saturated to separate all cyclohexanol from aqueous solution for example, 45. 72g of NaCl is needed to make solution saturated in 127mL of water. Required salt can be calculated by multiplying solubility of salt in water with minded(p) volume.In part B, there was cyclohexanol found in the condenser because temperature of water test in the condenser was low compare to melting point of cyclohexanol, which is 24C so some of the cyclohexanol was stuck on the inner-surface of the condenser. Cold-water was turned off, and hot-water turned on when cyclohexanol was collecting during distillation process to remove the cyclohexanol from the surface of condenser and used in the final product. The result shows that the percent yield is 35. 5%. As ex pected percent yield is low because the strong acidic conditions and solubility of cyclohexanol in water (Hornback, 2006).Observed musing index is very close to lit value of reflective index of cyclohexanol, which tells that product is pure but there is still some impurities. The result is also due to inefficient experiment procedures. This experiment required precise measurements of data in order to obtain accurate results. But, there are many possible sources of experimental error when performing this experiment. Firstly, if water-acid solution was not cooled enough to add cyclohexene, then some of the cyclohexene have evaporated.Cyclohexene is a limiting reagent meaning it will adjoin the boilers suit weight of cyclohexanol by reducing the come. Secondly, not using properly clean and dried equipments may affect on reactants activities, much(prenominal) as a flask, beaker, graduate cylinders. Thirdly, solution was not homogeneous in other words, flunk to mix properly for the reaction to go to completion. It was hard to judge due to very dark colour of the solution. If reaction was not fully reacted means not all cyclohexene were reacted to form protonated cyclohexanol and cyclohexyl hydrogen sulfate.Fourthly, some potassium carbonate may have entered in distillation flask which resulted in volte-face reaction causing to lose more cyclohexanol. Fifthly, a small amount of product might be lost when transferring from one container to another. Sixthly, some cyclohexanol was odd in round-bottom flask in order to prevent the round-bottom flask from breaking due to over-drying or over-heating. There are a few methods that would improve the accuracy of the experiments, if considered and followed with care. While recording the volume from the graduated cylinder the goal is to look for at the curve on the top of a standing body of liquid.Before experiment takes place make sure to clean all equipments that are going to be used passim experiment to avoid any be side reactions in the experiment that may affect the final result. When transferring from one flask to other, sometimes filter paper would be a better solution to prevent unwanted product from immersion into a reaction flask, and to prevent any reverse reaction to occur, such as potassium carbonate. Conclusion In this paper, distillation process for the substantiative hydration of cyclohexene to cyclohexanol using sulphuric acid as an acidic catalyst is demonstrated.In the hydration process, duplicate bond of cyclohexene is replaced by the hydroxyl group to form alcohol. Obtain reflective index of cyclohexanol is 1. 4648, and the literature value of reflective index of cyclohexanol is 1. 4641at 20C which shows that final product was very pure. The result also showed that the percent yield is only 35. 5%, it is due to the strongly acidic conditions and solubility of cyclohexanol.