December 4, 2020


Aim for Excellence

A Solventless Aldol Condensation Experiment for the Organic Chemistry Laboratory

Planet Journal of Chemical Schooling. 2020, 8(3), 104-106. DOI: 10.12691/wjce-8-3-1 Summary Aldol condensation reactions are...

Planet Journal of Chemical Schooling. 2020, 8(3), 104-106. DOI: 10.12691/wjce-8-3-1


Aldol condensation reactions are routinely employed in organic chemistry teaching labs. In this experiment, we made a greener technique for the aldol condensation experiment of the Organic Chemistry II lab at North Carolina Point out College. To do this, we employed the 12 Principles of Green Chemistry, and altered our recent method to fit as many of them as feasible. The most important solution employed through this process was acquiring aldol condensation reactions that had been completely solventless. We at present have a method that enables for all feasible combos of two aldehydes: four-tolualdehyde and four-anisaldehyde, and two ketones: acetophenone and four-methylacetophenone. We have made a technique that not only lessens solvent use, but also qualifies underneath 5 other inexperienced chemistry concepts: prevention of waste, less hazardous chemical synthesis, reduction of derivatives, accident prevention, and atom financial state. This new experimental design enables learners to pick out the compounds they would prefer to use from a list of offered reagents as a result making it possible for a sure diploma of lab personalization.

1. Introduction

Green Chemistry is a promptly rising self-discipline aimed at building chemical reactions and products and solutions that minimize the creation of hazardous substances. 1 The twelve concepts of inexperienced chemistry lay the basis for this purpose and have to be utilized at all options to maximize the greenness of the preferred response. The recent technique of imagining about Green Chemistry was made in 1987 from the United Nations Fee on Surroundings and Enhancement. This commission described sustainable development as “…conference the demands of the existing without the need of compromising the potential of foreseeable future generations to meet their possess demands.” two This commission paved the way to the development of the 12 concepts of inexperienced chemistry, laid out under. 1

two. Principles of Green Chemistry:

1. Prevent Waste

two. Atom Economic climate

3. Less Hazardous Synthesis

four. Style Benign Chemical compounds

5. Benign Solvents & Auxiliaries

6. Style for Energy Efficiency

7. Use of Renewable Feedstocks

8. Decrease Derivatives

9. Catalysis

10. Style for Degradation

11. True-time Analysis for Air pollution Prevention

12. Inherently Benign Chemistry for Incident Prevention.

In new several years, the greening of organic chemistry teaching labs has been well underway, with various publications and displays at conferences involving new lab experiments that included the concepts of inexperienced chemistry. 3 From alkene isomerization to reduction of a ketone to oxidation of alcohols, many experimental techniques have been made to alter the organic chemistry labs. two Even acylation reactions, such as lidocaine synthesis, have been modified to put into practice inexperienced chemistry. four Green Chemistry does not just have software in organic chemistry nevertheless, it can utilize to nanotechnology and even into business. 5, 6 Introducing the concepts of inexperienced chemistry into teaching or industrial labs is explained to have many benefits beyond just environmental. A person review pointed out that integrating inexperienced chemistry into teaching labs at an introductory collegiate degree lead to an increase in students’ passion for each chemistry and the inexperienced movement. 6

Aldol condensation reactions have been analyzed thoroughly, as they are 1 of the most major standard techniques for the formation of carbon-carbon bonds in organic chemistry. 7 This response is a prevalent experiment completed in a sophomore degree organic chemistry lab. When many scientists have aimed to combine inexperienced chemistry into the aldol response, they have generally arrive with a key disadvantage, such as significant hazards or significant waste creation. 8 Palleros (2004) released a detailed paper in the Journal of Chemical Education that supplied many illustrations of this response. 9 From this, we aimed to make a realistic useful resource to use inside of an undergraduate teaching lab.

We have been fascinated in the incorporation of inexperienced experiments in our organic chemistry lab curriculum. 10 In this experiment, modifications have been produced to the conventional aldol condensation employed in labs on campus, in buy to make it greener. These improvements consequence in a quicker response time (when compared to the conventional method), an elimination of the need to have for a solvent, a reduction in the amount of money of waste generated, and a simpler response method. 9, 11 The modifications satisfy six of the twelve concepts of Green Chemistry: prevention of waste, reduction of derivatives, safer solvents and auxiliaries, safer chemistry for accident prevention, less hazardous chemical synthesis, and maximization of atom financial state.

3. Experimental

3.1. Reagents Made use of

The pursuing chemical substances had been utilized in this experiment: four-tolualdehyde, four-anisaldehyde, four-methylacetophenone, acetophenone, and sodium hydroxide pellets, as well as a 10% aqueous HCl alternative. Reagents had been procured from Sigma-Aldrich and Fisher Scientific and employed without the need of further more purification.

3.two. Method

This method is written for all feasible combos of the two aldehydes and two ketones previously mentioned in the Reagents Made use of part. Working with a volumetric pipet, .50 mL of the chosen aldehyde and .forty mL of the chosen ketone had been included to a mortar. Approximately .10 g of solid NaOH was included to the response and then employing a pestle, was crushed up inside of the alternative. The response was floor till the formation of a solid was noticed. Immediately after the solid commenced to sort, the combination was permitted to sit for 10 minutes, to make certain completion. When the 10 minutes experienced handed, two mL of 10% aqueous HCl had been included to neutralize any residual NaOH. This combination was then permitted to sit for an additional 10 minutes, ahead of vacuum filtration was executed. The sample was washed with a compact amount of money of chilly ninety% ethanol.

3.3. Dangers

The use of proper personalized protective equipment, such as eye protection, by scientists was required at all moments in the laboratory. Ethanol was handled with warning owing to flammability. Both equally aldehydes (four-anisaldehyde and four-tolualdehyde) are air delicate, so the containers had been lined with parafilm to stay clear of contamination. In addition to this, the reagents employed are eye, skin, and respiratory irritants and had been dispensed inside of a fume hood. Made use of solvents and filtrate had been disposed of in the organic unwanted liquid content container, even though solid solution was disposed of in the organic unwanted solid content container.

four. Outcomes and Discussion

This experiment was designed to present a inexperienced different to conventional aldol condensation reactions inside of a next semester organic chemistry lab. Introducing a method that incorporates many concepts of inexperienced chemistry, such as reduced auxiliaries, atom financial state, and waste reduction, could be helpful to learners. The conventional method calls for learners to combine acetone and acetophenone with a 1:1 95% ethanol: 3M sodium hydroxide alternative in an Erlenmeyer flask. The learners then stir intermittently for fifteen minutes, isolate the solution, and recrystallize. This method leads to very low yields and impure products and solutions (as decided by melting stage examination). 11 The proposed method will need learners to mix 1 of two aldehydes (four-tolualdehyde or four-anisaldehyde) with 1 of two ketones (acetophenone or four-methylacetophenone) in the presence of a pellet of sodium hydroxide in a mortar. The learners then grind the alternative till a solid is noticed. Subsequent, they use a compact amount of money of 10% HCl to neutralize the solution, adopted by filtering and washing with chilly ninety% ethanol. No recrystallization was important with these products and solutions as they have average to significant purity based mostly on IR spectroscopy and melting stage examination, with the exception of the blend of anisaldehyde and acetophenone, which did not react.

Table 1 exhibits the a few combos of aldehydes and ketones that had been tested in this experiment. These combos (solutions 1-3) are then compared to the conventional aldol response completed with benzaldehyde and acetone in Table two.

Table two under exhibits a comparative examination of the greenness of the two strategies. The comparison was limited to the 6 concepts of inexperienced chemistry that the proposed method improved from the prior technique.

As noticed in Table two, the proposed technique features many inexperienced benefits when compared to the recent 1, such as the elimination of solvent, reduction of waste and derivatives, curtailment of hazardous dangers, enhancement of atom financial state, and enhancement of accident prevention. An additional advantage of the proposed method is that with the various options and reduction of response time, learners are in a position to synthesize much more than 1 solution, consequently giving them much more practice with the various methods employed. College students also have much more time to analyze the IR spectra and melting stage knowledge to figure out the relative purity of the solution.

5. Summary

The aldol condensation is a extremely valuable response in organic chemistry for its potential to sort carbon-carbon bonds it is also a somewhat very simple method in use in many teaching labs. Some recent techniques tend to consequence in very low yields and purity. In this experiment, we redesigned this technique to increase the inexperienced chemistry facet of the response and increased the range of feasible reagents in buy to give learners a diploma of choice when completing the experiment. The modifications of the experiment to meet the concepts of inexperienced chemistry resulted in a new method that not only generated significant yields and purity, but also removed the use of solvents, reduced derivative formation, reduced chemical dangers, increased atom financial state, and diminished the likelihood of incidents.


We thank the Office of Chemistry at North Carolina Point out College for economical assistance of this undertaking.


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Revealed with license by Science and Education Publishing, Copyright © 2020 Theresse M. Robinson, Melinda C. Box and Maria T. Gallardo-Williams

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Cite this report:

Usual Fashion

Theresse M. Robinson, Melinda C. Box, Maria T. Gallardo-Williams. Select Your Personal (Green) Journey: A Solventless Aldol Condensation Experiment for the Organic Chemistry Laboratory. Planet Journal of Chemical Schooling. Vol. 8, No. 3, 2020, pp 104-106.

MLA Fashion

Robinson, Theresse M., Melinda C. Box, and Maria T. Gallardo-Williams. “Select Your Personal (Green) Journey: A Solventless Aldol Condensation Experiment for the Organic Chemistry Laboratory.” Planet Journal of Chemical Schooling 8.3 (2020): 104-106.

APA Fashion

Robinson, T. M. , Box, M. C. , & Gallardo-Williams, M. T. (2020). Select Your Personal (Green) Journey: A Solventless Aldol Condensation Experiment for the Organic Chemistry Laboratory. Planet Journal of Chemical Schooling, 8(3), 104-106.

Chicago Fashion

Robinson, Theresse M., Melinda C. Box, and Maria T. Gallardo-Williams. “Select Your Personal (Green) Journey: A Solventless Aldol Condensation Experiment for the Organic Chemistry Laboratory.” Planet Journal of Chemical Schooling 8, no. 3 (2020): 104-106.