Introduction: In this experiment, the identity and absolute configuration of an unknown chiral secondary alcohol will be determined using NMR and CEC. By using the given NMR data, the identity of the alcohol an be determined. In order to identify the stereochemistry of the alcohol, it will have to undergo an esterification reaction in which propionic anhydride, two enantiomers of HBTM(each used in different reactions), and triethylamine are used. Thin layer chromatography will be run at a specified time in the reaction, and the results will be examined both quantitatively(via ImageJ) and qualitatively to which reaction reacted more quickly. With this information, the stereochemistry of the alcohol can be deduced. Theory: The competing enantioselective …show more content…
It requires each enantiomer of the chiral acyl-transfer catalyst called homobenzotetramisole (R-HBTM and S-HBTM) and thin-layer chromatography (TLC). Identifying which HBTM enantiomer led to a faster reaction with the unknown chiral alcohol, and the use of a mnemonic allows for the identification of the configuration of the alcohol. In order to identify which HBTM enantiomer led to a faster reaction, a run TLC plate will be photographed (with a smartphone or any other photo-taking device) and a quantitative analysis will be performed using a program called ImageJ. In order to determine the molecular structure of the unknown alcohol that is received in lab, H NMR spectroscopy will be used. The rate of an enantioselective reaction for a matched alcohol and catalyst is faster than that of a …show more content…
Therefore, the alcohol will prefer to react from the bottom face of the catalyst. Depending on which enantiomer of the alcohol is used, the reaction can occur quickly, or slowly. If the S-alcohol is used, the OH group will be positioned closer to the carbonyl, allowing for a quicker reaction. This would be a matched pair. If the R-alcohol is used, the OH group will positioned further from the carbonyl, leading to the reaction requiring more time. Furthermore, as the OH group approaches the carbonyl, the methyl group that neighbors the OH group will sterically interact with the phenyl group, repelling the alcohol from the carbonyl. This would be a mismatched pair. On the other hand, if the catalyst that was used is S-HBTM, then the phenyl group will be positioned down(as shown in the below image). Therefore, the alcohol will prefer to react from the top face. If the S-HBTM is reacted with the R-alcohol, the OH group will be positioned close to the carbonyl group, allowing it to react faster. This would be a matched pair. If, instead, the S alcohol is used, the OH group would be positioned further away from the carbonyl, leading to a slower reaction. This would be a mismatched
Nevertheless, the effects caused by the breakage of bonds will eventually lead to a decrease in the rate of reaction. As seen in the data, the reaction rate increased from 0.088 to 0.101 throughout the interval of -5℃ to 20℃ then decreased to 0.037 throughout the interval 20℃ to 56℃. This can be explained by the fact that 20℃ is the optimal temperature, therefore the active site of the enzyme is complementary to the substrate, causing the rate of reaction to be
In this experiment, the goal was to identify the unknown monoterpene assigned by infrared spectroscopy, ultraviolet-visible spectroscopy, and 1H NMR spectroscopy. The hypothesis was that the unknown monoterpene was citronellol. The hypothesis was confirmed through the spectroscopes conducted. The ultraviolet-visible spectroscopy showed a 214nm with an absorbed energy of 1.006ε. Since it was under 220nm, it showed that there was only one double bond in the molecule.
It forms a complex with HBr and extracts it from the aqueous phase into the organic phase where the alkene is. This dehydrates the acid, making it more reactive so that the addition reaction is possible. Rapid stirring is required in order to maximize the surface area
Tetraphenylcyclopentadienone (0.100 g, 0.260 mmol), dimethyl acetylenedicarboxylate (0.1 mL), and nitrobenzene (1 mL) were placed in a small reaction tube along with a boiling stick. The reaction tube was heated to a reflux using a sand bath until the purple soln. turned a tan color. When the soln. was warm to touch, ethanol (3 mL) was stirred in.
Esters have the RCOOR’ functional group, as depicted in the diagram. Esters are formed by reacting an acid and an alcohol together. In the case of diamorphine hydrochloride, the two alcohol
ABSTRACT The public profile of forensic science has dramatically increased in recent decades and there has been a corresponding rise in the number of students undertaking forensic science degree courses at tertiary level with the view to a professional career in this field. During this period the application of modern analytical techniques to the examination of small and portable cost-effective instrumentation. The availability of new techniques has led to a greater choice of tools that can be employed to analyse forensic specimens. An understanding of a broad range of analytical tools is required by today’s forensic chemist and is an important aspect of their training.
In science class, we did an experiment to compare inks and their compositions. This was intended for us to learn about chromatography; the separation of a mixture through a medium (the chromatography paper) in which the components move at different rates and create different patterns. We chose to explore this topic by using four different colored markers, placing a dot of each color onto one piece of chromatography paper, and observing while the water in the beaker travels up the paper and separates the dyes. Before we started, we made a hypothesis. Mine was if paper chromatography is done on the ink in the green, red, brown, and black marker, then the green will spread out into different shades of blue and green making a pointed oval shape.
Leah Romero 10/30/2017 Conclusion Lab 3 Chem 102L In lab 3, fundamentals of chromatography, the purpose was to examine how components of mixtures can be separated by taking advantage of different in physical properties. A huge process in this lab was paper chromatography, which was used to isolate food dyes that are found in different drink mixes. The different chromatograms of FD&C dyes were compared to identify which dyes are present in each of the mixes.
Cross Condensation of aldol 2015007632 Dowrie, K Contents Reaction 1 Introduction 1 Experiment Procedure 2 Experimental results 3 Table of calculations 3 Calculations 3 NMR 4 TLC 4 References 5 Reaction Introduction An aldehyde reaction is when aldehydes and keytones, both containing an α-hydrogen in the presence of an alkali group condenses and forms an enone. Acetone has α-hydrogens on each side. The proton can be removed and therefore giving a nucleophile anion. The aldehyde carbonyl is more reactive than the keytone and so it reacts rapidly with the anion.
Next, the oxygen is protonated from the 3-nitrobenzaldehyde, which is then followed by an elimination reaction where this acts as a leaving group. The product is the trans-alkene present in the product. After the reaction was completed, purification of the product was conducted using semi-microscale recrystallization.
Introduction: We have seen that the carbonyl group of aldehydes and ketones is highly immediate, and that accompaniments to this functionality are ordinary. Carbonyl functionality reactive but that it also activates to hand carbon-hydrogen bonds (particularly alpha hydrogen’s) to go through a variety of substitution reactions.1 Carbonyl compounds can be explained by just four fundamental reaction types: Nucleophilic additions Nucleophilic acyl substitutions α-Substitutions Carbonyl condensations2 α-Substitutions: Alpha-substitution reactions take place at the site next to the carbonyl group the α-position and occupy the substitution of an α hydrogen atom by an electrophile, E,
In the control, beta-amylase was present unlike the experiment, which resulted in less molecules lingering. Discussion: 1. a. My results matched my prediction regarding alcohol percentage by weight.
The possible explanations and changes to make are similar to the previous questions. Conclusion and Future Experiment 18. The identity of the product and unknown were 4-tert-butylbenzyl phenol ether and tert-butyl phenol respectively. The key to making this discovery was the melting point and TLC results!
Introduction Circular dichroism (CD) is form of light absorption spectroscopy that measures the difference in absorbance of right- and left-circularly polarized light (rather than the commonly used absorbance of isotropic light) by a substance. It is applicable for molecules have one or more chiral chromophores [1]. Circular dichroism = ΔA(λ) = A(λ)LCPL - A(λ)RCPL, where λ is the wavelength This technique measured a molecule over a range of wavelengths. All chiral molecules can be studied, particularly in study of large biological molecules.
Conclusion The GC ethanol analysis method described above has a simple concept, its rapid, and extremely accurate, determining ethanol precisely without interference from other beverage components. With this method, it takes only 7 to 8 min to complete a sample analysis for the determination of ethanol content in a beverage sample. Analyst handling is minimized to prevent deviation in results or possible human error. This method requires a gas chromatograph and a digital integrator, both reasonably expensive and sophisticated pieces of equipment.