CHEM360: Reaction Workup-Recovery and Purification of the Ester - Characterization of the Ester - Science Assignment Help

Assignment Task

Use the CHEM360 Lab Manual and your CHEM360 Report Book to complete your lab reports. Consult your CHEM360 textbook for any necessary targeted topical readings. Watch the short videos found below on the Organic Chem Resources page if you are not familiar with a particular technique.

For the best outcome, work on one experiment at a time and read the CHEM360 Lab Manual experimental procedure first, and then match up and transcribe the data and observations with each procedural step. Once done, then you can then begin to fill out the CHEM360 Report Book templates.

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If you have any questions on how to proceed, please contact the Science Lab Coordinator, (Mr.) Rob Carmichael at (robertc@athabascau.ca or 1-800-788-9041 ext. 6729).

Wishing for your best success in these exceptional times.

Experiment 10 Raw Data and Observations
Table 10.2 Chosen pair of carboxylic acid and alcohol. 

1. All reagents are clear and colorless solutions.

2. Set up a reflux apparatus as shown in Figure 10.5, used a clean and dry condenser and 100 mL sized roundbottomed flask.

3. Measured out and added 13.2 mL* (0.12 mol) isoamyl alcohol to the 100mL round-bottomed flask.

4. Measured out and added 27.6 mL* (0.48 mol) of acetic acid to the 100 mL r.-b. flask already containing the alcohol. *show calculations for target weigh-outs.

5. After mixing of alcohol and carbox. acid, reaction mixture is still a clear and colorless solution

Part B. Synthesis of the ester

1. Added 5 boiling stones to the 100mL round-bottomed flask containing the alcohol and carbox. acid.

2. 2.7 mL (~0.05 moles) of concentrated 18M sulphuric acid slowly and carefully added, with swirling and cooling the flask.

3. Quickly reassemble the reflux apparatus, and heat the reaction for 45min, while maintaining a steady reflux.

4. Immediately after addition of 2.8 mL of 18M sulfuric acid = reaction mixture is still a clear and colorless solution

5. After reflux for .5 hr = rxn. mixture is a light 'peach' colored solution

Part C. Reaction Workup-recovery and purification of the ester

1. After ether addition = two layers formed in the separatory funnel (upper layer is ether + product), ether layer pale yellow in color

2. After each 2 x 25 mL sodium carbonate washes = vigorous bubbling occurredin the separatory funnel. (CO2 gas bubbles produced!)

3. Final simple distillation of the ester = bp is 130-135 C (uncorrected)

4. Barometric pressure = 705 mmHg, (source of error = thermometer is uncalibrated)

Part D. Characterization of the ester

Final product, isoamyl acetate, 10.36 g, nD at 22 C = 1.3998 Product is a clear liquid with a very faint peach tinge of color and strong odor of bananas. See next 3 pages for infrared spectra to analyze.

Acetic acid (thin liquid film on KBr)

Isoamyl alcohol (thin liquid film on KBr)

Isoamyl acetate (thin liquid film on KBr)

Experiment 12 Reaction Observations

Appearance of benzophenone - white semi translucent crystals
Amt of benzophenone weighed = 1.35 g
Appearance of benzophenone solution – clear and colorless
Appearance of sodium borohydride – dull white powder
Appearance of sodium borohydride solution – slightly cloudy
Amt of sodium borohydride weighed = 0.60 g (modification to procedure -excess added)
Slow dropwise addition of sodium borohydride sol’n to benzophenone sol’n – slight clouding occurred where drop contacted the benzophenone sol’n that disappeared with mixing
After all sodium borohydride add’n – reaction mixture slightly cloudy
Reaction mixture after stirring for 5 min. – became a very thick white slurry
Crude reaction mixture chilled for 30 min on ice
During vacuum filtration product washed with 2 x 10 mL of ice cold distilled water
Appearance of Impure Diphenylmethanol after vacuum filtration – dull white powder after drying
Experiment 12 Recrystallization Observations
Impure Diphenyl methanol (dried) -not weighed
Appearance of solvent selected = n-hexane = clear and colorless
Volume of hot solvent used to dissolve the impure diphenylmethanol = 20 mL
Hot gravity filtration performed: Appearance before charcoal addition = clear/colorless solution
Appearance after charcoal addition = clear/colorless solution with black charcoal powder throughout
Appearance after gravity filtration = black charcoal powder on filter paper, filtrate = clear and colorless
Appearance after cool down = crystals formed after 5 minutes, white shiny needles growing in flask
Experiment 12 Results Summary Part A
Appearance of final purified diphenylmethanol - white shiny needles
Yield of final purified diphenylmethanol = 1.1268 g
mp of final purified diphenylmethanol = 67.5-68.3 C
mixed mp of purified diphenylmethanol + mp standard = 67.5-68.0 C

Benzophenone Infrared Spectrum (KBr disc)

Diphenylmethanol Infrared Spectrum (KBr disc)

Experiment 13 Reaction Observations

Appearance of benzaldehyde – clear colorless liquid, smell of almonds
Amt of benzaldehyde dispensed = 4.00 mL
Appearance of acetone – clear colorless liquid
Amt of acetone dispensed = 1.5 mL (show calc to determine amt of reagent to use)
Appearance of 95% ethanol – clear colorless liquid
Amt of 95% ethanol dispensed = 25.0 mL
Appearance of 1M NaOH – clear colorless liquid
Amt of 1M NaOH dispensed = 30.0 mL
After combination of all reagents – reaction mixture slightly yellow in color
Reaction mixture after stirring for 10 min. – became a very thick yellow slurry
Crude reaction mixture chilled for 30 min on ice
During vacuum filtration product washed with 2 x 10mL of ice cold 95% ethanol, 10mL ice cold
95% ethanol with 4% acetic acid, and finally with 10mL ice cold 95% ethanol -filtrate sl. yellow color
Appearance of Impure aldol product after vacuum filtration – light yellow powder (not weighed)
Experiment 13 Recrystallization Observations
Appearance of Impure aldol condensation product after drying overnight -fine light yellow powder
Appearance of solvent selected = 95% ethanol = clear and colorless
Volume of hot solvent used to dissolve the impure aldol product = 85 mL (colored product so gravity filtration with black charcoal powder not done)
Appearance after cool down = crystals formed after 5 minutes, yellow shiny needles growing in flask
Experiment 13 Results Summary
Appearance of final purified aldol product - yellow shiny needles
Yield of final purified aldol product = 1.92 g
mp of final purified aldol product = 113-3-114.0 C
mixed mp of purified aldol product + mp standard = 113-114 C. 

CHEM360 Experiment #14 1 H?NMR Spectra Analysis

Chose and submit any four 1 H?NMR unknowns found on our website.

Username = auchem360    password = synthesis

Use the tables below to record your results of the ‘ 1 H?NMR Spectral Analyses’ of your chosen unknown spectra.  Be sure to also print off the unknown spectra and label them thoroughly.

CHEM360 Experiment #15  Rxns of Common Funct'l Grps: Aldehydes and Ketones

Results Part A&B. Reaction with 2,4?dinitrophenylhydrazine, Silver Mirror

Experiment 16 Observations and Notes:

Part A: Preparation of Phenylmagnesium Bromide

1. Pre-dried all glassware overnight in drying oven at 110 C.

2. Use granular calcium chloride (white round lumps) in drying tube.

3. Appearance of magnesium = dull grey shavings, mass used = 2.44g

4. Appearance of diethyl ether = clear and colorless liquid = volume used = 10 mL

5. Appearance of Bromobenzene = clear and colorless liquid, volume used = 10.5 mL (show calculation to determine volume to use from the molecular weight and density)

6. Volume of diethyl ether used to rinse over bromobenzene and added to separatory funnel = 50 mL

7. It took 15 min for reaction to get started (pt. 6.). Clouding and small bubbles seen on surface of magnesium. Very small evolution of heat sign. Not noticeable to touch but enough to begin reflux/boiling of ether.

8. Matched reflux drop rate with addition drop rate of bromobenzene + ether from the separatory funnel. ~1 drop per second.

9. Addition of bromobenzene complete after 20 min. Reflux sustained for another 20 min using hot water bath as heat source. Reaction mixture gradually changed color from an initial white cloudy solution to a purple brown color.

Part B: Reaction of Phenylmagnesium Bromide with Ethyl Benzoate

1. Appearance of Ethyl benzoate = clear and colorless liquid, volume used = 7.0 mL (show calculation to determine volume to use from the molecular weight and density)

2. Volume of diethyl ether used to rinse over ethyl benzoate and added to separatory funnel = 15 mL 3. In pt.

3, solution turn from purple/brown to orange brown to a tan color when all the ethyl benzoate has been added and it is finished warming for 30 min.

4. Matched reflux drop rate with addition drop rate of ethyl benzoate + ether from the separatory funnel.

5. Addition of ethyl benzoate complete after 10 min. Reflux sustained for another 30 min using hot water bath as heat source.

6. Some product crystallized. Added small amount of diethyl ether (5 mL) to re-dissolve/slurry.

Part C: Isolation of Triphenylmethanol

1. Used 5mL diethyl ether to rinse and assist transfer from round bottom flask to 400mL beaker
2. Appearance of 2M Sulfuric acid = clear and colorless; volume used = 50 mL
3. Used 75 mL of fresh diethyl ether to assist in transfer to 250 mL separatory funnel
4. Appearance of 0.6 M sodium hydrogen carbonate = clear and colorless sol’n.; used ~100 mL
5. Throughout all washings the retained top/upper layer (diethyl ether + product) was clear and colorless.
6. Appearance of high boiling point petroleum ether = clear and colorless liquid, volume used = 25 mL
7. Distillation of the diethyl ether took 40 min. Boiling point of ether = 32 C (uncorrected; bar.press.=710 mm Hg).
8. Solid crude triphenylmethanol are white crystals.
9. Used 100% ethanol for recrystallization (45 mL). 

Part D: Observation of Carbocation

1. After addition of conc. sulfuric acid to triphenylmethanol product, solution becomes brilliant golden yellow/red color. No heat is generated.

2. After addition of conc. sulfuric acid to diphenylmethanol, a yellow pptte forms becoming a white cloudy solution. Heat is generated. (see Part D results table below for full observations).

Part E: TLC Analyses

1. Use short wave UV to visualize spots on TLC. (see Part E sketch below).

2. Appearance of dichloromethane and ligroin = both clear and colorless liquids

 

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