Multistep Synthesis of Tetraphenylcyclopentadienone Essay

October 5, 2017 General Studies


The purpose of this experiment was to execute a multistep synthesis to organize tetraphenylcyclopentadienone. The first measure of the reactions was to synthesise benjamin from the condensation of benzaldehyde. A output of 28. 91 % benjamin was obtained. The MP of benjamin was 127O-130O C and the IR spectra displayed a carbonyl extremum at 3415 cm-1. . which represents and OH functional group. The 2nd measure of the reaction was to oxidise benjamin to organize benzil ; this reaction yielded 27. 04 % benzil. The MP of the benzil was 91O-93O C and the IR spectra revealed no OH functional groups. The last measure of the synthesis was a dual aldehyde-alcohol condensation reaction to organize tetraphenylcyclopentadienone ; this reaction had a output of 76. 56 % and a liquescent point of 222O-225O C. The IR spectra revealed a ketone carbonyl extremum at 1700 cm-1.


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In this experiment a multistep reaction will be performed in order to synthesise tetraphenycyclopentadienone. The merchandise will be synthesized in three stairss. but in the industrial universe companies frequently produce compounds that involve up to twenty stairss. Tetraphenycyclopentadienone is produced by synthesising benjamin through the condensation of benzaldehyde and vitamin B1 being used as a accelerator. In the 2nd measure of the reaction. benjamin is oxidized to benzil ; azotic acid is used as the oxidising agent in this measure. In the last measure of the reaction. a mixture of benzil and 1. 3-diphenylacetone undergo a dual aldehyde-alcohol condensation reaction so a desiccation reaction in order to organize tetraphenycyclopentadienone.

* Thermometer
* Round underside flask ( RBF )
* Reflux capacitor
* Hot home base
* Hirsh Funnel
* Melttemp 2. to mensurate runing point
* Microlet IR 100. to mensurate IR

Benzoin Condensation of Benzaldehyde

First 1. 20 gms of benzaldehyde was weighed out and set into a RBF incorporating a magnetic splash saloon. Following 225 milligram of vitamin B1 was dissolved in 0. 67 milliliter of H2O and 2. 0 milliliter of 95 % ethyl alcohol. This mixture was added to the RBF and 3 M NaOH was added bead wise until the solution turned a bright xanthous colour. If excessively much 3 M NaOH is added so the solution will turn a dark gold colour ; in this state of affairs an extra 200 milligram of vitamin B1 should be added. The xanthous solution was stored in a vial until the following hebdomads lab. so the mixture would hold a suffienct sum of clip to respond.

At the start of the following lab the phial was cooled in an ice bath to accomplish complete crystallisation. Next. a Hirsch funnel was used to filtrate the crystals ; the crystals were washed three times utilizing a 50:50 mixture of cold ethanol/water and left to dry. Once dry. the merchandise was recrystallized utilizing 95 % ethyl alcohol. The benjamin obtained ( 0. 370 g ) had a percent output of 28. 91 % and runing point of 127O-130O C. The IR spectrum displayed a strong carbonyl extremum at 2912 cm-1. a little OH extremum at3415. 24 cm-1 and an olefine group at 1472 cm-1 which represented the conjugated phenyl rings.

Oxidation of Benzoin to Benzil

This reaction was begun by puting all the benjamin that was synthesized in the old lab into a RBF along with a magnetic scaremonger. 1 milliliter of concentrated azotic acid was added to the RBF ; the RBF was so attached to a reflux capacitor and submerged into a hot H2O bath at 100oC for 30 proceedingss or until no more exhausts are observed. A vacuity with a funnel attached to the terminal was placed on top of the reflux capacitor in order to roll up any nitrogen oxide exhausts that formed. Once the reaction stopped bring forthing exhausts. the reaction mixture was left to cool ; when the mixture reached room temperature the contents in the RBF where transferred utilizing a Pasteur pipet into a beaker incorporating 3 milliliter of H2O.

Extra H2O was used to rinse out the RBF and it was poured into the beaker in order to see maxim output of benzil. Following mixture was stirred inside the beaker utilizing a glass splash rod. At this clip the benzil should get down to organize a xanthous solid ; the solid was crushed utilizing the terminal of the glass rod and filtered utilizing a Hirsch Funnel. The benzil crystals were washed with cold H2O in order to take any azotic acid that was present on the crystals. After rinsing the crystals three times with cold H2O. the crystals were dried and weighed out.

The petroleum benzil was so recrystallized utilizing a 95 % ethanol solution. The recrystallized merchandise was cooled in an ice bath and filtered with 95 % ethyl alcohol. The crystals were dried and weighed once more. The percent recovery of the benzil synthesized had a percent output of 26. 29 % . The runing point of the benzil was 910-930. Last. the IR spectra displayed extremums at 2917. 35 cm-1. 1681. 56 cm-1 and 1595 cm-1.

Synthesis of Tetraphenylcyclopentadienone

In the last portion of the work up. tetraphenylcyclopentadienone was synthesized through a dual aldehyde-alcohol condensation reaction. A H2O bath was foremost prepared and heated to 100o C. Next the benzil produced in the old measure was place inside of a RBF. An equimolar sum of 1. 3-diphenylacetone ( 0. 092 g ) and 1 milliliter of 95 % ethyl alcohol was besides added to the RBF. Once all three compounds were added the RBF a magnetic splash saloon was added to the RBF so it was connected to the reflux capacitor. Once all of the solids in the mixture were dissolved. 0. 15 milliliter of 30 % KOH solution was added utilizing a Pasteur pipet ; the add-on of KOH turned the mixture a dark brown colour.

The mixture was left to respond for 20 proceedingss and it was so cooled to room temperature. Once the mixture reached room temperature the RBF was placed in an ice bath for about 10 proceedingss. The crystals formed were so filtered utilizing a Hirsch funnel and washed three times with 0. 5 milliliter of cold ethyl alcohol. 0. 113 gms of pure Tetraphenylcyclopentadienone was obtained. the output was 76. 56 % . and the MP was 222O-225O. The IR spectrum of the concluding merchandise displayed extremums at 1700 cm-1. which correlates to ketone carbonyl functional groups.


Benzoin Condensation:

Benzoins: 0. 370 gms
Theoretical Output: 1. 28 gms
Percent Output: 28. 91 %

Experimental Melting Point ( Co ) | Literature Melting Point ( Co ) | 127-130| 135-137|

Infrared Spectroscopy

Experimental Peak ( cm-1 ) | Functional Group| Literature Peak ( cm-1 ) | 3415. 24| OH| 2500-3600|
2912. 12| Aromatic C-H| 3030|
1472. 81| Phenyl Alkene| 1500-1600|
* The merchandise formed was xanthous crystal.

Oxidation of Benzoin to Benzil

Benzil: 0. 092 gms
Theoretical yield:0. 350 gms
Percent Output: 26. 29 %

Experimental Melting Point ( Co ) | Literature Melting Point ( Co ) | 91-93| 95|

Infrared Spectroscopy

Experimental Peak ( cm-1 ) | Functional Group| Literature Peak ( cm-1 ) | 2917. 35| Aromatic C-H| 3030|
1681. 56| C=O| 16900-1715|
1595. 87| Phenyl alkene| 1500-1600|
* The losing OH extremum is important. The merchandise formed was a white crystal.

Synthesis of Tetraphenylcyclopentadienone

Tetraphenylcyclopentadienone: 0. 113 gms
Theoretical output: 0. 1476 gms
Percent Output: 76. 56 %

Experimental Melting Point Co| Literature Melting Point Co| 222-225| 218-220|

Infrared Spectroscopy

Experimental Peak ( cm-1 ) | Functional Group| Literature Peak ( cm-1 ) | 1700| C=O| 1690-1715|

* Final merchandise formed was a deep purple colored crystal.


In this lab the condensation of benzaldehyde with thiamine moving as a nucleophile formed benjamin. Thiamine was used because its hydrochloride is stable and acts as a nucleophilic accelerator. Thiamine besides attaches itself to the carbonyl of the benzaldehyde making an intermediate that has a negatively charged C atom and is able to assail the 2nd benzaldehyde molecule. When the reaction is complete. the thiamine accelerator disassembles from the benjamin. Cold H2O and ethyl alcohol are used in this reaction so that the in this reaction the reactants will go more soluble making a homogeneous mixture. The benjamin obtained had a percent output of 28. 91 % . a runing point of 127O-130O C and distinguishable IR extremum at 3415. 14 cm-1. stand foring an OH group. The MP and IR spectra confirmed that this compound was so benzoin.

The following measure in the synthesis was the oxidization of benjamin in order to organize benzil. In this measure. the OH group nowadays in benjamin is deprotonated and the azotic acid is attached. Once the azotic acid attaches. the C and O are able to organize a dual bond. which creates benzil. Adding H2O to the mixture makes the azotic acid become a better go forthing group by deprotonating the reaction intermediate. The benzil obtained had a percent output of 26. 91 % ; a runing point of 91O-93O C and the IR spectra displayed a benzil ketone carbonyl group extremum at 1681 centimeter -1. In add-on there was no OH extremum on the IR spectrum. The absence of the OH extremums indicated that there was no unreacted benjamin in the concluding merchandise.

In the last measure of the synthesis a dual aldehyde-alcohol condensation was used to organize tetraphenylcyclopentadienone. An equimolar sum of 1. 3-diphenylacetone was added to the benzil and so deprotonated by the add-on of KOH. The benzil yielded negatively charged Cs of the carbonyl groups because of the lose of the alpha H to KOH. The bonding of the carbonyl groups caused a hydride displacement because the O become negatively charged and attracts the next H.

Last. a dual bond between two Cs and an intoxicant group is formed ; the intoxicant groups is dehydrated doing the 2nd aldol condensation to happen with the other O nowadays on benzil. The per centum output tetraphenylcyclopentadienone was 76. 56 % . the MP 222O-225O C. and the IR spectrum displayed a strong extremum at 1700 cm-1. The dual aldol condensation appeared to work good because of the high output obtained and the IR spectra and MP supported the concluding merchandise being tetraphenylcyclopentadienone.


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