To build acene backbone the Diels-Alder reaction can be used. Byproduct free [4+2] cycloaddition is especially enticing due to the fact that in the employed synthesis strategy the starting diene is not purified before the reaction. To synthesize diene bisacetal decomposition is deployed. The initial reaction is employing diketone which forms acetal with methanol under acidic conditions. To shift the equilibrium of reaction to the products direction, the three times excess of methyl orthoformiate is introduced. It reacts with water, removing it from the reaction sphere and forms methanol, ensuring constant excess of alcohol. Like this, there is no need in constant distillation commonly employed during this type of reaction. The last step of reaction is the distillation, which serves double purpose: the bisacetal decomposition proceeds during heating along with methanol removal, which shifts the equilibrium from the acetal formation. The formed conjugated system can be readily polymerized in acidic conditions, so the hydroquinone is added as polymerization inhibitor. …show more content…
The diene and diketone has close boiling point, in order to obain pure product few time-consuming distillations are needed. This is why the next reaction in the synthesis should utilize the crude product. The product of Diels-Alder reaction can be easily purified by column chromatography. The resulting anthraquinone is reduced to hydro derivative and using the condensation with orthodiformylbenzene in the presence of Na2CO3 tetracene is obtained. The formation of quinone is especially enticing, as it is more stable to the photooxidation, comparing to acenes. Anthraquinone can be easily reduced to the target molecule or it can be functionalized in the exact position which is especially important for the tetracenes
The experiment of Diels-Alder reactions, in particular the furan and maleic anhydride as used in my experiment, observed the exo product as oppose to the exo product. This shows the tendency for the stereochemistry of the Diels-Alder to yield an exo product in preference to the endo product. To determine the stereochemistry, a melt temperature of the product was taken and compared to literature values. The melt temperature for the product was roughly around 113oC, corresponding to the exo Diels-Alder product of furan and maleic anhydride. When compared to the class data of melting ranges, the melting temperature from the reaction was relatively consistent to the majority. Based off this, the assumption can be made that the Diels-Alder prefers
The goal of this two week lab was to examine the stereochemistry of the oxidation-reduction interconversion of 4-tert-butylcyclohexanol and 4-tert-butylcyclohexanone. The purpose of first week was to explore the oxidation of an alcohol to a ketone and see how the reduction of the ketone will affect the stereoselectivity. The purpose of first week is to oxidize the alcohol, 4-tert-butylcyclohexanol, to ketone just so that it can be reduced back into the alcohol to see how OH will react. The purpose of second week was to reduce 4-tert-butylcyclohexanol from first week and determine the effect of the product's diastereoselectivity by performing reduction procedures using sodium borohydride The chemicals for this lab are sodium hypochlorite, 4-tert-butylcyclohexanone
This week’s lab was the third and final step in a multi-step synthesis reaction. The starting material of this week was benzil and 1,3- diphenylacetone was added along with a strong base, KOH, to form the product tetraphenylcyclopentadienone. The product was confirmed to be tetraphenylcyclopentadienone based of the color of the product, the IR spectrum, and the mechanism of the reaction. The product of the reaction was a dark purple/black color, which corresponds to literature colors of tetraphenylcyclopentadienone. The tetraphenylcyclopentadienone product was a deep purple/black because of its absorption of all light wavelengths. The conjugated aromatic rings in the product create a delocalized pi electron system and the electrons are excited
The goal of this lab is to synthesize maleic anhydride with polyethylene glycol of 200g/mol molecular weight (PEG 200) and 2,3-dimethyl-1,3-butadiene to get 4,5-dimethylcyclohexane-1,2-dicarboxylic acid anhydride and its diacid by using Diels-Alders reaction and hydrolysis, respectively. The crystals were determined using melting point determination and IR spectroscopy.
The sole purpose of performing the lab was to utilize aldol condensation reactions to synthesize a cyclopenta-dienone, while using UV spectrophotometry and computer visualization to further understand the dienone. In the beginning of the lab, the tetraphenylcyclopentadienone (TPCP) was synthesized using dibenzyl ketone and benzyl under extremely basic conditions. The synthesis process could be further understood by observing the mechanism portrayed in Figure 1. According to the figure, the dibenzyl ketone will first loose an alpha hydrogen to form the enolate intermediate.
In addition to this, these compounds also display antagonist activity to calcium 23. For this reason, and for their associated pharmacological properties, a lot of interest and attention has been drawn to them in the recent years by researchers 22. A couple of methods have consequently been developed for the preparation of the octahydroquinazolinone derivatives 2. The most common of which include the Biginelli one pot reaction that involves urea/ thiourea, aromatic aldehydes and dimedone 24. Other methods include synthesis with the help of catalysts like concentrated sulfuric acid, Nafion-H, ionic liquid, and TMSCI 24. Synthesis in low ethanol could also be adopted but it is characterized with product yields that are between 19-69% and these are
This reaction is carried out at low temperatures because the diazonium salt is stable at low temperatures. At low temperatures the system is stable and the molecular movement is quite low. Potassium iodide and water is added and the mixture separates, the mixture is put on a hot plate and heated to 40ᵒ once the mixture has reached this temperature a vigorous reaction occurs, gas evolution (purple gas) and the separation of the tan solids take place, this happens because once the gas is let out the carbon receives a plus charge given from the electron which turns in to a free radial which is more stable than a plus charge. When this reaction completes the chorine and the free radical combine. Potassium iodide works as a facilitator for this
In this experiment, a multistep synthesis was performed, electrophilic aromatic substitution took place, and a protecting group was used. The compound that resulted from the synthesis was sulfaniliamide. In order to get this product, three reactions took place.
The preparation of 2,6-dimethylaniline is a reduction reaction. Step two is the preparation of -chloro-2,6-dimethylacetanilide. This second step is an acylation reaction. The final step in the synthesis is the preparation of lidocaine.
It was added carefully. Then heated under reflux for 1 hour. After cooling to room temperature, the reaction was quenched by pouring the mixture into a beaker of ice and saturated ammonium chloride solution(20ml). The layers were separated and the aqueous layer was extracted with diethyl ether (2 x 20ml). The combined organic layers were washed with water and saturated aqueous NaCl solution, dried on NasSO4. After filtration, the mixture was put on the rotavap and the product crystallized. An NMR was taken to determine if the right product was
Figure 2: Formation of 1,1-Diphenylethanol with Grignard Reagent Afterwards, the Grignard reagent was added to acetophenone to form 1,1-diphenylethanol. Ammonium chloride was added to protonate the oxyanion (acid workup). Results and Discussion Figure 3: Grignard Reaction Mechanism
Hydrophobic rate acceleration. Breslow and his co-workers first explored the effect of water on the rate of Diels-Alder reactions in a quantitative manner3. This was done by comparing the rates of reaction in Figure 2 in isooctane, methanol and water. It was found that all three reactions proceeded significantly faster in water than in nonpolar organic solvent. Solvent polarity effect was not the reason for the enhancement of the reaction. It was found that the reaction between 1.1 (cyclopentadiene) and 1.2 (acrylonitrile) was only slightly faster than isooctane. The reaction between 1.8 (9-hydroxymethylanthracene) and 1.9 (N-ethylmaleimide) was found to be slower in methanol than the isooctane due to the disrupted hydrogen-bonded association of the diene and dienophile. This was a good evidence that there are other factors affecting the reaction in water.
In this lab, it was determined how the rate of an enzyme-catalyzed reaction is affected by physical factors such as enzyme concentration, temperature, and substrate concentration affect. The question of what factors influence enzyme activity can be answered by the results of peroxidase activity and its relation to temperature and whether or not hydroxylamine causes a reaction change with enzyme activity. An enzyme is a protein produced by a living organism that serves as a biological catalyst. A catalyst is a substance that speeds up the rate of a chemical reaction and does so by lowering the activation energy of a reaction. With that energy reactants are brought together so that products can be formed.
The yield of the crude acetanilide was fair (98.45%). This was apparent from the melting point of the sample. The melting point of the crude acetanilide (116-123℃) had a fair comparison to the literature melting points (113-115℃(R1.). The yield of the recrystallized acetanilide was about half of the yield of the crude acetanilide. The recrystallized contained the key functional group. For instance,
The quinolinone and quinoline ring is highly prevalent in natural compounds. There are synthetic and potential agents, which show various pharmacological properties (Priya et al., 2012). Quinolinones are important structural intermediates for synthesis of functionalized quinolines (Baston et al., 2000). Quinolines have demonstrated various applications such as biomedical (Ridley et al., 2002), fungicides (Oliva et al., 2003), virucides (Liu et al., 1997), biocides (Sabatini et al., 2013), alkaloids (Fournet et al., 1993) rubber chemicals and flavoring agents (Jones et al., 1996). They