Alkene hydration
objectives
demonstrate the preparation of alcohols by the reaction of alkenes with water and acid.
predict the products formed from the acid-catalyzed addition of water to an alkene.
design a synthesis based on the desired product and available reactants.
introduction
in this experiment, the compounds that you are to synthesize are 1-methylcyclohexanol and 2-hexanol. these are both electrophilic addition reactions.
alkene hydration procedure
enter the synthesis lab [left-hand desk]. click on alkene hydration on the chalkboard. decide on the appropriate starting reagents to synthesize 1-methylcyclohexanol from what is available. to make that decision, consider which of the available reagents could form a cyclo product, and consider what objective 2 says you're doing in this experiment.
build the necessary experimental set-up. add the appropriate reagents to a flask, and move the flask to the stir plate. the experimental setup requires the use of a heater, condenser and n2 gas, as in the previous experiment. add the catalyst. [note that access to the chemicals in the bottles with the red caps is only allowed after the flask is on the stir plate.]
you will monitor the reaction on the chalkboard and with tlc. since you'll be doing two different syntheses in this experiment, you'll need to organize your tlc plate results so that you know what result belongs to which synthesis. so, click on your lab book, and title a page 1-methylcyclohexanol, and then close the book window. when you move to a new synthesis, title a new book page with the name of that compound.
run a tlc plate before you start the reaction, and save it. some reactants may not show up on tlc so make sure that you check the contents of the reaction vessel on the chalkboard. every time you run a tlc plate, the clock will advance 5 minutes.
note the time on the laboratory clock. start the reaction by turning on the stir plate. advance the laboratory clock by an interval of 1 minute and run another tlc plate and check the chalkboard. save the tlc plate.
repeat this step, including saving the tlc plate, until you note the appearance of product on the tlc plate or on the chalkboard. note the time and the size of the tlc spot. continue to advance the clock in 20-minute intervals. run another tlc plate and check the chalkboard at each interval. note the time it takes for reaction completion. (reaction completion means that the starting material will no longer be present in the reaction vessel as indicated on the chalkboard and the tlc plate.)
before going on to the next synthesis, click on your lab book, and save a screenshot of the first and last tlc plates that you ran. label the screenshots 1-methylcyclohexanol start and 1-methylcyclohexanol end. calculate the rf for 1-methylcyclohexanol. in your lab book, click on edit and choose a new page.
clean up by clicking on the red container in the lower right of the window.
repeat the procedure to synthesize 2-hexanol, so title your new lab book page 2-hexanol.
calculate the rf's for each of the compounds you made.
in preparation for the assessment, draw the structures of the organic reactants and products appearing in this experiment. have available the rf's you calculated, your tlc plate screenshots, and the reaction times you were asked to record.
also, make sure to review the topic of alkene hydration, in your text or elsewhere.
12-in order to have access to the assessment, you will need to submit your starting and final tlc screenshots. insert the screenshots into a single word-processor document, and then label them in the document so that your instructor can tell what compound they represent, and which is the starting and which the final tlc. then upload the final document containing the screenshots into the assignment link below, and submit it. upon submission, the assessment will become available.