Question

SYNTHESIS OF T-PENTYL CHLORIDE LAB

Provide a stoichiometry table for the reaction being performed in this lab.

PROCEDURE Preparation oft-Pentyl Chloride In a 125-mL separatory funnel, place 10.0 mL of tert-pentyl alcohol (2-methyl-2- butanol, MW = 88.2, d = 0.805 g/mL) and 25 mL of concentrated hydrochloric acid (d 1.18 g/mL). Do not stopper the funnel. Gently swirl the mixture in the separa- tory funnel for about 1 minute. After this period of swirling, stopper the separatory funnel and carefully invert it. Without shaking the separatory funnel, immediately open the stopcock to release the pressure. Close the stopcock, shake the funnel several times, and again release the pressure through the stopcock (Technique 12, Section 12.7). Shake the funnel for 2-3 minutes, with occasional venting. Allow the mixture to stand in the separatory funnel until the two layers have completely sepa rated. The tert-pentyl chloride (d = 0.865 g/mL) should be the top layer, but be sure to verify this by adding a few drops of water. The water should dissolve in the lower (aqueous) layer. Drain and discard the lower layer Extraction The operations in this paragraph should be done as rapidly as possible because the tert-pentyl chloride is unstable in water and sodium bicarbonate solution. It is eas- ily hydrolyzed back to the alcohol. In each of the following steps, the organic layer should be on top; however, you should add a few drops of water to make sure. Wash (swirl and shake) the organic layer with 10 mL of water. Separate the lay- ers and discard the aqueous phase after making certain that the proper layer has been saved. Add a 10-mL portion of 5% aqueous sodium bicarbonate to the sep- aratory funnel. Gently swirl the funnel (unstoppered) until the contents are thor- oughly mixed. Stopper the funnel and carefully invert it. Release the excess pressure through the stopcock. Gently shake the separatory funnel, with frequent release of pressure. After this, vigorously shake the funnel, again with release of pressure, for about 1 minute. Allow the layers to separate and drain the lower aqueous layer Wash (swirl and shake) the organic layer with one 10-mL portion of water and again drain the lower aqueous layer. Transfer the organic layer to a small, dry Erlenmeyer flask by pouring it from the top of the separatory funnel. Dry the crude tert-pentyl chloride over 1.0 g of anhydrous calcium chloride until it is clear (Technique 12, Sec- tion 12.9). Swirl the alkyl halide with the drying agent to aid the drying. Distillation Transfer the clear liquid to a dry 25-mL round-bottom flask using a Pasteur pipette Add a boiling stone and distill the crude tert-pentyl chloride in a dry apparatus (Technique 14, Section 14.4, Figure 14.11). Collect the pure tert-pentyl chloride in a receiver cooled in ice. Collect the material that boils between 78°C and 84°C. Weigh the product, calculate the percentage yield, and determine the boiling point (Tech- nique 13, Section 13.2). Determine the infrared spectrum of the product using salt plates (Technique 25, Section 25.2). Submit the remainder of your sample in a prop- erly labeled vial, along with the infrared spectrum, when you submit your report to the instructor

Answer 1

Male cular We ight 88.2 9/ml Amount used Number OF Moles Reagent No. 0f equivalents Density t-pontyl alcohal 0.805 orL 10 mL. 0.0913 mal HCU 8.86 36.4169/ral 1.18 /L 25 mL. 0.8091 mal Ceone.)

I have left the No. of equivalents of t-pentylalcohol blank because, with reference to t-pentylalcohol the number of equivalents of concentrated HCl is calculated.

Calculation:

Density = Weight/Volume

So we can calculate the weight of the reagent used by,

Weight = Density × Volume

10 ml. ot tert- phent alcoho density of tord -phenyt alcoha e 0.805 gmL we'ght of tert-pheny alcohal valume x densiy 10 mL x 0.805 7/m 1 8.05 g 1 No. of males of tert-phenyk alcohal welght malar mass on moseculan weigh 8-05 88.2 O.0913 maL volume of concentrated Hu 25 mL. donsi청 아 Ha welght of Heu Valume n densty 1.18 7/mL 1.189/ 29.59 29.59 No. 0f moles of Hd 36.46 9mal O.809 1 mal 1

No. of equivalents of Conc. HCl = (No. of mole of t-pentylalcohol ÷ No. of moles of HCl)