Solved by Expert Tutors
Solved by Expert Tutors
Question

I apologize with the order! However I need help on question 3 of my organic chemistry lab! Down below I gave the experimental procedure from 1-7 and what I have completed so far!

This report must be an independently
Your lab mark (out of 10) will be determined by the pre-lab, interactive video, and this report.
1. Calculate the % yield of the ammonium tartrate salt crystals you filtered, based off the original
mass of racemic amine you started with (page 18 in the manual).
NOTE: the density of the liquid amine is 0.94 g/ml.
* * *The experimental mass of the collected (-)-amine-(+)-tartrate salt was found to be = 7.89 q
R-NH2 + C4H606 - R-NH3+-tartrate
racemic amine
tartaric acid
121 g/mol
150 g/mol
ammonium tartrate salt
- 392 9/ mol-
(+ ) - tartanc acid = 12.09
3.) (+ ) - a -phenylethylamine
(* ) : a-phenylethylamine- (racemic) = 10 mL
(racemic )
Density of liquid amine= 0. 94, 9 / ml.
is the limiting reagent
Dit tartanic acid .
(4.) (070 7 7) . 392 9 / mol ) = 30
mol
12.09
= 0.0 8 mol
5)
actual yield = 7. 89 9 to
150 g/ mol
( Jamine - (+) tartrate salt
( I ) - 9- phenylethylamine ( rakemic ) :
6. )
% yield :
7. 89g
X 10
Oml X. 0.94 9 / ml = 9:49
30, 1849)
9. 49
121 g/ mol
= 0. 077 mol
2. Hopefully the % yield from question 1 was 50% or less. Why would a percentage yield greater
than 50% be undesirable in this experiment?
A percentage yield greater than 50 % would be undesirable in
experiment, because if a racemic mixture is present, it mee
it has a 50:50 ratio ( with the, 2 enantiomers). Therefore
purpose of this expenment is to extract for one product cone
This in turn, would have a lower / yield than 50%, be
&quot; the yield percentage does not include the other en
3. Using &quot; R-NH3+ &quot; as shorthand for the cationic ammonium component of the salt you produced,
write down a balanced chemical equation showing the reaction with OH- and make sure to include
the product(s) produced.
EXPERIMENTAL 1. Obtain the corked flask set aside after experiment 1. Carefully decant (pour off) the liquid into the appropriately
labelled waste container, keeping the crystals in the flask. Add 10 mL of methanol to the crystals and suspend and break the mass up into individual crystals with a stirring rod. 2. Using a small Biichner funnel and filter flask, clamped properly to the retort stand, collect the crystals by vacuum
ﬁltration. Wash any remaining crystals out ofthe flask with a small amount of the filtrate and rinse the crystals on the
funnel with 10 mL of fresh methanol. Spread the crystals on paper to air-dry, then weigh the product and calculate the percentage yield of the (-)-a-phenylethylammonium hydrogen (+)-tartrate salt. 3. Place the crystalline salt product in a 125 mL Erlenmeyer flask. Add 30 mL of 2 M aqueous NaOH solution. Swirl the
mixture until all of the crystals have dissolved. You may notice the water turning cloudy or oily; this is normal (what is this due to?) Note: The next steps require a separatory funnel. its use will be demonstrated by your TA. 4. Transfer the aqueous NaOH-salt mixture to the separatory funnel using a plastic funnel (to minimize spillage). Rinse
the flask with 10 mL of dichloromethane. Add this rinse to the separatory funnel. Allow sufficient air space in the funnel to mix the liquids (as a general rule, never ﬁll a separatory funnel more than two-thirds to three-quarters full). 5. Stopper the funnel. Lift the separatory funnel out of its ring support and hold it with both hands to prevent the
stopper from falling out. Hold the rounded body in one hand, near the stopcock so that you can open and close the stopcock quickly to release pressure, but keep a finger of the other hand over the stopper at all times.
your BGIELY BIGBBEB III a lull IIIII UI BEPHIGIUIY IUIIIIEIB- 7. After the first venting, close the stopcock, swirl the inverted funnel for a few seconds, and then vent it again. If
excessive pressure build-up is evident, repeat the swirling-venting process until the pressure build-up is negligible. Then,
and only then, the funnel may be shaken vigorously for about 2 minutes with venting every 20 seconds or when
pressure builds. At the end of the shaking, vent the funnel again, return it to the ring support, remove the stopper, and allow the aqueous and organic layers to separate. 8. To withdraw the dichloromethane phase (and hence your amine), you must first know which layer is the organic layer.
As a general rule, the denser liquid is the layer on the bottom. Most organic solvents are less dense than water, with the
exception of solvents containing halogen atoms. Withdraw the dichloromethane layer into a clean and dry 50 mL Erlenmeyer flask, leaving the aqueous layer in the separatory funnel. 9. Extract this aqueous phase twice more with 5 mL portions of dichloromethane and combine these extracts with the
ﬁrst in the Erlenmeyer (repeat steps 5-8 with fresh solvent each time). Once all the extractions are finished, the aqueous solution in the separatory funnel can be discarded into the appropriate waste container. 10. To dry the dichloromethane extract, Add about 1 gram of anhydrous potassium carbonate (don’t measure this mass
exactly) to the Erlenmeyer flask and swirl, then let it stand for a few minutes. when the dichloromethane is dry, it will
appear clear (perhaps with a yellow colour) and the potassium carbonate will be easily settled on the bottom of the ﬂask. If this is not the case, you may need to add more potassium carbonate. 11. Weigh a clean and dry 50 mL beaker containing 1 or 2 boiling stones. 12. Filtering the dichloromethane solution into the pre—weighed beaker using a small cotton plug fitted at the constriction of a nlastic funnel. Rinse the cotton olue with 5 mL of fresh dichloromethane.

trices ac magna. Fusce dui lectus, congue vel laor

itur laoreet. Nam risus ante, dapibus a molestie consequat, ultrices ac mag

consectetur

acinia pulvi

cing elit. Nam lacinia pulvinar tortor nec

m cin s ct c c entes a. Fus m c c c nec facilisis. Pellentesque dapibus efficit m ipsum dolor sit amet, consectetur ultrices ac magna. Fusce dui lectus entesque dapibus efficitur laoreet. gue ve

### Why Join Course Hero?

Course Hero has all the homework and study help you need to succeed! We’ve got course-specific notes, study guides, and practice tests along with expert tutors.

• ### -

Study Documents

Find the best study resources around, tagged to your specific courses. Share your own to gain free Course Hero access.

Browse Documents