CHEM 269 Lecture Notes - Lecture 8: Boiling Chip, Nutmeg, Telomerase Reverse Transcriptase

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lemonplatypus384

30 Jun 2016

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Natural products chemistry: the isolation of trimyristin from nutmeg. Purpose: the purpose of this experiment was to use distillation to separate trimyristin, a fat, from the natural compound nutmeg. The trimyristin was then hydrolyzed to myristic acid through refluxing and hydrolysis. To a 5ml round-bottom flask (rbf) was added 1. 003g of ground nutmeg, 3ml of tert- butyl methyl ether, and boiling chips. The mixture was boiled gently for 10 minutes, and then allowed to sit until all solids settled. The liquid was pipetted out without any solid into a centrifuge tube, then filtered through a pipet tip with a cotton plug into a 25ml flask. To the rbf, 2 ml of tert-butyl methyl ether was added, and the liquid was filtered through the tip with the cotton plug into the 25ml flask. The solution was dried in the flow hood with a stream of air until a yellowish solid appeared (trimyristin).

Related Questions

% yield question

20.34 mL diethyl malonate, 50mL sodium ethoxide, 14.38mL n-butyl bromide made 9.11g diethyl n-butylmalonate

% yield question

To a 250 mL round-bottomed flask were added 35 mL of absolute ethanol and 50 mL (0.134 mol) of NaOEt solution and stirred. The flask was then fitted with a reflux condenser and a dropping funnel via claisen adapter and a drying tube was attached. Diethyl malonate (20.34 mL, 0.134 mol) was added portion-wise over 15 min through dropping funnel. Then to the clear solution was added n-butyl bromide (14.38 mL, 0.134 mol) dropwise. The reaction mixture was refluxed for 10 min and then cooled. The solution was then mixed with 200 mL of cold water and aqueous layer was extracted four times with 50 mL portion of ethyl ether. Combined organic layer was dried over MgSO₄, filtered, and ether was evaporated over steam bath. Remaining solution was transferred into a pre-weighed round-bottomed flask and simple distillation (temp <90 ËC) was performed to remove excess ether and ethanol. The product diethyl n-butylmalonate (amount) was obtained as pale orange liquid in ____% yield.

Please consider the preperation of benzoic acid: a Grignard Reaction.

Bromobenzene and diethyl ether is used in the formation of Grignard reagent.

PLEASE READ PROCEDURE TO HELP ANSWER THE QUESTION:

Procedure(question is in the pic below):

* add 1.2g of magnesium and 3 crystals of iodine to RB flask and immediately assemble the dry water condenser and drying tube containing cotton and anhydrous calcium chloride to RB flask

*then add 5.2 mL bromobenzene to 5 mL of diethyl ether to seperatory funnel and turn on condenser

* add about one third of ether-bromobenzene mixture down the condenser into the RB flask by momentarily removing drying tube. Place the drying tube back as quickly as possible.

* now add 30 mL of ether to the bromobenzene-ether mixture remaining in the seperatory funnel

*to initiate reaciton, place hands under flask and gently swril

* once the reaction maintains reflux, remove hands and set the flask down on a cork ring

*maintain the vigorousness of the reaciton by continuously adding 3.5 mL portions of diluted bromobenzene-ether mixture every 30 seconds

* make sure all of the bromobenzene-ether mixture has been added

* now obtain some dry ice, CO₂ (s) and transfer 50 mL of this to the reaciton mixture inside the flask

*when all the dry ice has been added, add 80 mL of 6M HCl (aq) to flask

* finally, add 100mL of solvent grade diethyl ether (not anhydrous) and carefully stir

* transfer mixture to a 250mL seperatory funnel, allow layers to seperate and discard the lower aqueous layer

*now add 20 mL of 6 M NaOH (aq) and add 100mL of deionized water to seperatory funnel containing the ether solution

* drain the lower aqueous layer into a large beaker and slowly acidify using concentrated 12M HCl (aq). Stir the mixture and add HCl (aq) until pH is about 1-2 pH units.

*cool solution in ice-water bath and collect precipitate of benzoic acid

QUESTION:

Please do not forget to identify the phase that each compound is in. Thanks!

The overall reaction is given in the following pic:

Grignard theoretical yield... also, what is the limiting reactant?

Procedure: The Claisen adapter is fitted to the neck of a 100 mL round bottom flask containing 1-2 crystals of solid iodine and 0.5 g of magnesium metal (Mg). In the side arm of the adapter, place a reflux condenser with water hoses connected, but not flowing. Insert the vacuum connecting tube into the top of the condenser. Place the glass stopper into the other joint of the connecting tube and attach a DRY piece of rubber tubing connected to a drying tube. The drying tube should have two cotton plugs and sufficient DRIERITE (anhydrous CaSO4) between them to ensure that any air getting into the system is dried by the Drierite. Place the separatory funnel in the straight arm of the adapter. Open the stopcock so there is a flow path from the funnel to the flask. Insert a second vacuum connecting tube into the top of the separatory funnel. Place the glass stopper into the other joint of the connecting tube and attach a DRY piece of rubber tubing connected to a drying tube. The drying tube should have two cotton plugs and sufficient DRIERITE (anhydrous CaSO4) between them to ensure that any air getting into the system is dried by the Drierite. Once the apparatus is assembled, use a heating mantle on medium heat to heat the flask until sublimed iodine appears on the inside walls of the flask (rosy color). Close the separatory funnel. The apparatus should now be dry enough to allow formation of the Grignard reagent to occur. After the apparatus has cooled, start the water flowing gently through the condenser. To prepare the phenylmagnesium bromide, add 5 mL of anhydrous ether to the flask (through the separatory funnel) followed by 0.5 mL of bromobenzene. Close the stopcock on the separatory funnel. After a minute or so, bubbling should occur as the reaction begins and the reaction mixture should begin to turn slightly brown. If no reaction appears to begin, warm the flask gently with your hand. When the reaction begins, add 1.5 mL of bromobenzene in 15 mL of ether, and add this solution to the separatory funnel. Slowly add the bromobenzene solution from the separatory funnel dropwise at a rate of about two drops per second. This should be a rate sufficient to keep the reaction going without further heat. There should be sufficient heat from the reaction to maintain the ether at reflux. If the reaction appears to be going too fast and the ether vapors are high on the walls of the reflux condenser, use an ice bath to cool the reaction to the point that the ether vapors are no more than one-third of the height of the reflux condenser. When all of the bromobenzene has been added, heat the reaction at reflux for about 25 minutes with a low heat heating mantle. Prepare a solution of 2.25 g of benzophenone in 10 mL of anhydrous ether (in the closed separatory funnel

CHEM 269 Lecture Notes - Lecture 8: Boiling Chip, Nutmeg, Telomerase Reverse Transcriptase

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