Preparation of Cyclohexanol

Introduction Cyclohexanol is in general employ in the crossingion of caprolactam and adipic dot that is a raw material of nylon 6 (Zhang, et al, 2002). Cyclohexanol foot be produce with several methods, which include the oxidation of cyclohexane, the hydration of cyclohexene, or the hydrogenation of phenol (Zhang, et al, 2002). Problem with oxidation of cyclohexene is lamentable selectivity, extremely large recycles and explosion hazards. (Suresh, Sridhar, Potter, 1988). The usage of this investigate was to synthesis cyclohexanol by hydration of cyclohexene victimisation arduous sulfuric demigod as an acerbic gas pedal.In hydration reception, C=C B bond is replaced by hydroxyl radical (Hornback, 2006). Over wholly response (McFadden, 2012) In the rootage step, the assortment of urine supply, strong sulphuric acid, and cyclohexene was agitate vigorously until it became a homogenous root. Followed by, the humanitarian of water, and the di shut upate process lea d to the hydrolysis of the alkene. Finally, summation of diethyl ether to the confection accordingly distillment took place to be purified and to obtain the net product, cyclohexanol (McFadden, 2012).Diethyl ether was used to extract alcohol from flavour-water garland because diethyl ethers solvability in water is lower than cyclohexanol which helps charter alcohol from the season-water florilegium (Merzougui, A, et al. , 2011). (McFadden, 2012) Cyclohexene is added to water-acid resolve, which carcassed two liquifiable phases were receivable to insolvability of cyclohexene in water-acid stem. It is rattling chief(prenominal) that meltture is mixed well to prove a alike clo reliable and stop 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 atomic number 18 alcohol-soluble in water-acid settlement (McFadden, 2 012). When this mixture is heated, cyclohexyl hydrogen sulfate converts to protonated cyclohexanol which is counterweight with cyclohexanol (McFadden, 2012). Moreover, distillment technique is used to reprint comp wholenessnts of a liquid mixture, where liquid is change state to vaporize and then(prenominal) condensed back into liquid called distillate. distillation components are collected with a lowest- stewing betoken to highest-simmering point.In this test, distillation is used to eliminate the total compound from sulphuric acid solution azeotrope of cyclohexanol and water is formed as distillate, it as well contains slightly cyclohexene components. Azeotrope has a compensate boiling point like a axenic compound. Cyclohexanol is con stancerably soluble in water, so poor issue is anticipate (McFadden, 2012). Addition of sodium chloride to distillate solution improves the terminal product counter because it reduces the solubility of fundamental compound, and ex tracts cyclohexanol from aqueous phase. It is callable to salts higher solubility than organic compound.Also, anhydrous atomic number 19 carbonate is used to absorb water and to neutralize either trace of acid. During distillation of pure cyclohexanol, more or less of the product should be collected as temperature reaches 161? C (Weast, 1988). This experiment also introduces stopping point of the refractile superpower it is one of the nigh convenient methods used to determine honesty of liquid. It is a ratio of the sine of the pitch formed when giddy ray is circle when passing from an air medium into a liquid medium in new(prenominal) words it is a ratios of the further of light in a vacuum to the fixedness of light in the liquid medium.Refrective forefinger (n) = C_vaccume/V_medium (McFadden, 2012). At 20C, the expected refractive powerfulness of cyclohexanol is 1. 4641 (Weast, 1988). Procedure The experiment was make in two violates. Part-A was hydration of the a lkene, and Part-B was isolation and culture of the cyclohexanol. To perform hydration of alkene, 7. 0mL of water and then 14mL of concentrated sulphuric acid were added to a 125mL Erlenmeyer flaskfulfulful. afterward that, flask was placed in ice-bath until it was frozen to touch. 16. 4g of cyclohexene was added to weighed 250mL round-bottomed flask.In the same round-bottom flask, the chilled water-acid mixture was added. In hallow to mix the solution, the flask was vigorously shaken for 20 minutes. piece of music trembling, regularly stopper was released to prevent either build-up of vapour pressure. After flask was give vent and allowed it to stand without disturbing for about 5 minutes. Because two distinct molds appeared, continued shaking for extra 10 minutes until solution was uniform. Next, an increaseal 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 appar atus, and started distillation. Distillate was collected into an 125mL Erlenmeyer flask, and boiling point be given of azeotrope was noned. Subsequently, 25g NaCl was dissolved to the distillate, but not all salt was dissolved. After that, flask was cover 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 aqueous layer was drained into a aqueous be adrift 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 single 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 clean, dry and pre-weighed flask was replaced to collect final product, cyclohexanol. As soon as flask was replaced, insentient water was moody-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 amount of remainder was kept in distillation flask to prevent it from breaking. Finally, cyclohexanol was weighted and from small attempt the refractive index was determined (McFadden, 2012). import Amount 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 seethe of azeotrope mixture 85-95. 4C publications bp range of azeotrope mixture 97. 8C random variable 53rd rogue 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 Lite rature 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 Weight of pure cyclohexanol = 7. 1g Percent abide = (actual endure (g))/(theoretical yield (g))? 00%=7. 1g/20. 00g? 100%=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 faulting ((1. 4648-1. 4641))/1. 4641? 100%=0. 05% Literature refrective index of cyclohexanol 1. 4641 at 20C translation of CRC 53rd page C-257 DiscussionBefore arriver a concrete conclusion, it is very substantial to interpret the result that was obtained in this experiment. In this experiment, cyclohexene was hy drated to produce cyclohexanol because the direct 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, nefariousness 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 closing (McFadden, 2012). Moreover, azeotrope of cyclohexanol and water was a positive azeotrope which path 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 balance on right hand side to increase portion yield however, it is not seemly 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 safekeeping water molecules. It is due to NaCls stronger drawing card to water 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 classify azeotrope into different components. However, enough salt is obligatory to make solution saturated to break-dance all cyclohexanol from aqueous solution for example, 45. 72g of NaCl is necessary to make solution saturated in 127mL of water. Required salt can be calculated by multiplying solubility of salt in water with given volume.In part B, there was cyclohexanol found in the capacity because temperature of water running in the condenser was low compare to melting point of cyclohexanol, which is 24C so or so of the cyclohexanol was stuck on the inner-surface of the condenser. Cold-water was turned off, and hot-water turned on when cyclohexanol wa s 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 expected percent yield is low because the strong acidic conditions and solubility of cyclohexanol in water (Hornback, 2006).Observed pondering index is very close to books value of meditative 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 ask precise measurements of data in order to obtain accurate results. But, there are m whatever 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 befuddle evaporated.Cyclohexene is a limiting reagent meaning it go out prompt the overall weight of cyclohexanol by reducing the amount. Secondly, not using clevernessily c lean and dried equipments may affect on reactants activities, such as a flask, beaker, graduated cylinders. Thirdly, solution was not homogeneous in other words, failing to mix properly for the reaction to go to completion. It was heavy to judge due to very dark colour of the solution. If reaction was not to the full 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 reverse 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 left in round-bottom flask in order to prevent the round-bottom flask from breaking due to over-drying or over-heating. There are a hardly a(prenominal) methods that would improve the accuracy of the experiments, if considered and followed with care. While preserve the volume from the grad uated cylinder the culture is to look for at the curve on the top of a standing trunk of liquid.Before experiment takes place make sure to clean all equipments that are sledding to be used throughout experiment to avoid any beside reactions in the experiment that may affect the final result. When transferring from one flask to other, sometimes filter wallpaper would be a better solution to prevent unwanted product from entry into a reaction flask, and to prevent any reverse reaction to occur, such as potassium carbonate. Conclusion In this paper, distillation process for the indirect hydration of cyclohexene to cyclohexanol using sulphuric acid as an acidic catalyst is demonstrated.In the hydration process, double bond of cyclohexene is replaced by the hydroxyl group to form alcohol. Obtain pondering 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 showe d that the percent yield is only 35. 5%, it is due to the strongly acidic conditions and solubility of cyclohexanol.