This method includes acid-catalyzed dehydration of 4-methylcyclohexanol to provide 2-Chloro-4-methylpyridine. The liquid is distilled along with the water produced from the reaction flask. The distillate is washed , dried and distilled with oil.
A common laboratory approach for alkene preparation is to hydrate alcohols with heavy mineral acids, such as sulfuric acid, phosphoric acids, as a catalyst. The reaction is carried out in a distillation system. The lower boiling products (cyclohexene with boiling point = 83oC and water boiling point = 100oC) are diluted when the reaction mixture is heated and collected by the reception tank. Unreacted cyclohexanol and phosphoric acid (catalyst) are not extracted due to their high boiling points (161oC and 213oC) in the distillation cup. Nonetheless, in the receiving flask still appeareth a small amount of phosphoric acid, the sample is treated with aqueous sodium carbonate to neutralize the acid.
As we learn, cyclohexene is water insoluble, and is not lost by drying the substance with anhydrous sodium sulfate in crude cyclohexene. Sodium sulfate is a hydrate salt. Easy distillation guarantees final purification.
This week’s experiment, 4-methylcyclohexanol receives 4-methylcyclohexane as a result of acid-catalyzed dehydration. The substance is diluted with water from the reaction flask. Then the distillate is washed, dried and distilled with salt solution.
7.5 mL 4-methylcyclohexanol (molecular weight=114.2; boiling spot=171-173oC), 2.0ml 85% phosphoric acid, 30 drops of sulfuric acid concentrated in the potassium permanganate test reagent, saturated sodium chloride solution, granular anhydrous sodium, bromine test reagents.
50 mL round bottleneck flask, 25 mL round bottleneck flask, Erlenmeyer container, stirring glass tube, pipet Pasteur, boiling stones, distillation system, ice-water bath, heating cover, weighing balance.
Sulfuric and phosphoric acids are extremely corrosive. It is not appropriate to touch our bodies. The experiment has strong odors as several compounds are present, so that we have been cautious to smell them. Therefore, the sample was kept away from fire when small quantities of actions were checked while heated. We were still told to place
All dumped in the fume hood waste jar.
Assembly of the apparatus
The appliance for quick distillation was first mounted. As a flask distilling, 50 mL round bottom flask was used, and the 25 mL round bottom flask was used as a receiver. An ice bath around the receiver was installed to minimize product loss by evaporation. An empty 50 mL flask was weighted around the bottom. In the round lower bottom flask, 7.5 mL of 4-methyl-cyclohexanol was added using graduated pipette.
The temperature of the distillation was kept below 100oC. We continued to smoke or smash until just 0.5-0.6 mL of the residue remained on the distillation tank.
Product separation and drying
The distillate was transferred with 3ml saturated sodium chloride solution to a separation funnel. (The centrifugal tube and pasteur pipette are not to be used).
Before starting the distillation process, drying agent was prevented. The 25ml bottom round flask was used as a pre-weighed receiver. The most widely used range of temperatures is the boiling point of our 4-methylcyclohexenes.
Elimination reactions involve the removal from neighboring carbon atoms of a small molecule (H-X), leading to pi bond formation. Removal reactions are excellent synthetic methods for alkene processing. Such reactions take place in a mechanism called cleavage of the heterolytic bond. Heterolytic bond cleavage occurs when an atom releases a combination of the two initial bond electrons, resulting in the formation of ions. The leaving group leaves the initial C-X bond with both electrons. In the neighboring C-H bond the electrons form the alkene ‘s new pi bond with proton loss.
The dehydration reaction is called the removal of water (H-OH) from 4-methylcyclohexanol in this experiment. 4,4′-Bipyridyl dehydration, in many cases, is an acid-catalyzed reaction which proceeds through a disposal mechanism.