Isomerization OF Dimethyl Maleate INTO Dimethyl Fumarate () (2018 05 31 03 01 51 UTC) PDF

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Organic Chemistry Laboratory and Recitation II

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ISOMERIZATION OF DIMETHYL MALEATE INTO DIMETHYL FUMARATE

The objective of this experiment is to change dimethyl maleate into dimethyl fumarate within a reaction of bromine which will be studied under UV light. All the steps indicated in the experiment outline will be observed accordingly. In fact, the product will be purified by recrystallization, weighted, observed with a melting point, Theoretical yield calculated, and plotted on a TLC plate with Rf data calculated. The entire experiment will be monitored within

two goals in which one partner (the author of this report) will perform the experiment without the presence of lab lightbulb. On the other hand, another partner will conduct the experiment in regular lab lightbulb.

PROCEDURE: The procedure was executed with two partners where each individual had their correlated tasks to achieve during the whole experiment. So, it was required to wear gloves during those experiments because Bromine is very corrosive.

1-Experiment with sample performed without the presence of light I.

1ml of dimethyl maleate was diluted into a 3ml of dichloromethane in a 25ml Erlenmeyer flask. It was observed that the solution stayed clear color.

II.

A TLC plate was marked with a “0” minute’ mark. Using a TLC tube, one drop of the solution from the flask was added on the TLC plate. A rubber stopper covered the flask to prevent air influx.

III.

10 drops of 10% bromine in dichloromethane was added into the flask after the rubber stopper was removed. The solution automatically changed automatically to a dark orange color. A stir rod was submerged into the beaker where it was sited upon a stir plate for better solution mixing without the presence of light.

IV.

10 minutes later, the rubber stopper was again removed where another drop of the new reaction mixture was spotted on the TLC plate indicating 10 minutes’ mark. The rubber stopper was replaced afterwards.

V.

the beaker was stirring for an additional 10 minutes while being placed on the stir plate. Then the reaction mixture was spotted again on the TLC plate with 20 minutes’ mark. It was observed that the color remained the same.

VI.

Later, the beaker containing the solution was placed in an ice bath for over10 minutes while sample of hexane was poured into the beaker to activate the crystallization process.

VII.

20 minutes later, approximatively 2 ml of cold hexane was carefully drop into the beaker until crystal formation was partially formed.

VIII.

the crystals were carefully collected by vacuum filtration. the residue into the flask was cautiously washed with 1 ml of cold hexane until the formation of clear crystal into the vacuum filter.

IX. X.

the crystals weighted 0.237g. a little bit of crystals was collected into a melting point tube for the melting point purpose. The tube was inserted into the melting point apparatus and the melting point was 120ºC in which the process was repeated twice for confirmation.

XI.

a tip of spatula of crystals was dissolved with 1ml of dichloromethane in a test tube. The solution was spotted on the TLC plate with the DF mark. The TLC plate was placed into a 3:1 Hexane/Ethyl Acetate mixture and sealed for approximatively 10 minutes.

XII.

Finally, the TLC plate was positioned under the UV lamp as seen in the picture below where the Rf data were calculated accordingly.

Experiment I Data: Sample placed without illumination

Weight of Dimethyl Fumarate after recrystallization Volume of dimethyl maleate Added Volume of dichloromethane Added Volume of 10% bromine in dichloromethane Added Density Limiting Reagent Volume hexane Added Volume of Hexane/Ethyl Acetate Mixture Added Melting Point of Recrystallized Dimethyl Fumarate Percent Recovery (Weight of compound isolated ÷ Weight of starting material*) x 100

0.237g 1.0 ml 3.0 ml 10 drops ≈ 0.5 ml 1.15g/ml Dimethyl Maleate 3.0 mL 3.0 ml 120ºC after two attempts.

(0.237g/1.15g) x100 = [21%]

Calculations: 1.   

Atomic mass Units of Dimethyl Maleate and Fumarate C= 6 x 12.011= 72.066 H= 8 x 1.008= 8.064 O= 4 x 15.999= 63.996__ Total = 144.126 ≈ 144.13g amu

2. Density: 1ml Dimethyl Maleate  Density= 1.15g/ml 1ml x 1.15g/ml=1.15g 1.15g DM x mol/144.13g=0.0079 mol= 7.9mmol  0.0079mol x 144.13g/mol= 1.15 g Dimethyl Fumarate 3. Theoretical Yield:  % Yield= Actual Yield/ Theoretical Yield x 100% % Yield= 0.237 grams of Dimethyl Fumarate/1.15 grams of Dimethyl Fumarate X 100%= 21% 4. Rf Values (seen in the TLC Picture below): Rf= Distance the spot Traveled/ Distance the solvent traveled  Starting point to the solvent front=5.0mm  0 min= 3.0 mm Rf=3.0/5.0=0.56  10 min= 3.4mm Rf=3.4/5.0=0.63  20 min= 3.2mm Rf=3.2/5.0=0.60  Dissolved mark= 4.5mm Rf=4.5/5.0= 0.83

2- Experiment with sample performed with the presence of lab light bulb I.

1ml of dimethyl maleate was diluted into a 3ml of dichloromethane in a 25ml Erlenmeyer flask. It was observed that the solution stayed clear color.

II.

A TLC plate was marked with a “0” minute’ mark. Then, one drop of the solution from the flask was added. A rubber stopper was covering the flask to prevent air influx.

III.

10 drops of 10% bromine in dichloromethane was added into the flask after the rubber stopper was removed. The solution automatically changed automatically to a dark orange color. A stir rod was submerged into the beaker where it was sited upon a stir plate right under a lightbulb.

IV.

10 minutes later, the rubber stopper was again removed where another drop of the different reaction mixture was spotted on the TLC plate indicating 10 minutes’ mark. The rubber stopper was replaced afterwards.

V.

the beaker was stirring for an additional 10 minutes while being placed on the stir plate under light. Then the reaction mixture was spotted again into the TLC plate with 20 minutes. It was observed that the solution color changed to faint yellow. However, the color was getting clearer as it was exposed under light.

VI.

Later, the beaker containing the solution was placed in an ice bath for approximatively10 minutes while sample of hexane was poured into the beaker to activate the crystallization process.

VII.

10 minutes later, approximatively 2 ml of cold hexane was carefully drop into the beaker until crystal formation was completely formed.

VIII.

the crystals were carefully collected by vacuum filtration. the residue into the flask was cautiously washed with 1 ml of cold hexane until the formation of clear crystal into the vacuum filter.

IX. X.

the crystals weighted 0.2421g. a little bit of crystals was collected into a melting point tube for the melting point purpose. The tube was inserted into the melting point apparatus and indicated 99ºC.

XI.

a tip of spatula of crystals was dissolved with 1ml of dichloromethane in a test tube. The solution was spotted on the TLC plate with the DF mark. The TLC plate was placed into a 3:1 Hexane/Ethyl Acetate mixture and sealed for approximatively 10 minutes.

Finally, the plate was positioned under the UV lamp in which the Rf data were calculated accordingly.

Experiment II Data: Sample exposed to lab illumination Weight of Dimethyl Fumarate after recrystallization Volume of dimethyl maleate Added Volume of dichloromethane Added Volume of 10% bromine in dichloromethane Added Density Limiting Reagent Volume of hexane Added Volume of Hexane/Ethyl Acetate Mixture Added Melting Point of Recrystallized Dimethyl Fumarate Percent Recovery (Weight of compound isolated ÷ Weight of starting material*) x 100

0.2421g 1.0 ml 3.0 ml 10 drops ≈ 0.5 ml 1.15g/ml Dimethyl Maleate 3.0 ml 3.0 ml 99.0°C

(0.2421g/1.15g) x100 = [21.05%]

Calculations: 1.   

Atomic mass Units of Dimethyl Maleate and Fumarate C= 6 x 12.011= 72.066 H= 8 x 1.008= 8.064 O= 4 x 15.999= 63.996__ Total = 144.126 ≈ 144.13g amu 2. Density: 1ml Dimethyl Maleate  Density= 1.15g/ml 1ml x 1.15g/ml=1.15g 1.15g DM x mol/144.13g=0.0079 mol= 7.9mmol  0.0079mol x 144.13g/mol= 1.15 g Dimethyl Fumarate 3. Theoretical Yield:  % Yield= Actual Yield/ Theoretical Yield x 100% % Yield= 0.2421 grams of Dimethyl Fumarate/1.15 grams of Dimethyl Fumarate X 100%= 21.05% 4. Rf Values (seen in the TLC Picture below): Rf= Distance the spot Traveled/ Distance the solvent traveled  Starting point to the solvent front=5.4mm  0 min= 3.8 mm Rf=3.8/5.4=0.70  10 min= 4.0mm Rf=4.0/5.4=0.74  20 min= 4.0mm Rf=4.0/5.4=0.74  Dissolved mark= 4.2mm Rf=4.2/5.4= 0.78

TLC Plate for sample without regular lab lightning

Conclusion: The objective of this experiment was to facilitate the process of recrystallization dimethyl maleate into dimethyl fumarate within a reaction with bromine right under UV light. The entire experiment was monitored within two goals in order to carry out reactions without light and with regular lab lightning. In fact, the products were separately purified through recrystallization, crystals were weighted, melting point was obtained, Theoretical yield calculated, and plotted on a TLC plate with Rf data except they were exposed in different projection of light. Therefore, the purpose of the experiment was a success with both partners correlated data exhibited in the data table throughout this report. As a result, errors found in the experiment may have been a result of mistakenly adding to many solutions into the tubes /or on the TLC plate which could alter the identification of the compounds or eventually human error.

Reference: Oragnic Chemistry Laboratory 2 Manual CHEM 2584, experiment: “Isomerization of Dimethyl Maleate into Dimethyl Fumarate” Structures, mechanism and steps....