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Nmr Spectra Lab Report

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Again the 13C NMR spectra is consistent with the back bone or cholesterol remaining constant in the reaction. There are 27 carbon environments in the spectrum which matches that starting material. There is an evident peak at 201.25 ppm which is due to the C=O in the molecule. The carbon that had the bromine added, in chlestan-3-one this carbon is at 38.36 ppm and in this spectrum using the HSQC spectrum this peak was identified to be at 54.67 ppm which shows an increase in chemical shift. This is evident that the bromine has added as the increase in chemical shift is expected when a halogen is added to an alkane bond. Figure 9 Thin later chromatography of cholestan-3-one (left) and 2α-bromocholestan-3-one (right). Thin later chromotography was used to idneitfy that the reaction had go to completion. The starting material was spotted on the left, cholestan-3-one and on the right was 3. The TLC plate showed that there was a differnce between the …show more content…

However, on work up the first product was not collected from the column. This resulted in further analysis on the mixture of the two products and chole-1-en-3-one. Using IR spectroscopy, the two spectrums appeared identical as expected as the shift in the double bond is the only difference between the two products. The IR spectrum shows that the cholesterol backbone is still present as there is a C-H stretch at 2926 cm-1, consistent with sp3 hybridised carbon in the molecule as well as CH2 groups as there is a stretch at 1464 cm-1. The only other significant stretch is a C=O, at 1719 cm-1 which identifies that 4 still has the ketone group produced in the oxidation of the secondary alcohol in the second step. There is not a peak at 550 cm -1 which shows that the elimination of the bromine atom has taken

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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

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The purpose of this experiment was to perform a bromination reaction that converts cyclohexane to trans-1,2-dibromocyclohexane. To do this, 1 mL of 30% hydrogen peroxide was mixed with 3 mL of bromic acid in a round bottom flask containing a spin vane. The solution turned from clear to orange, dark red. The color change is a useful indicator to identified whether reaction was completed before moving to another step. Next, 1 mL of cyclohexene was pipet into this mixture, which changed the solution from red to orange and eventually yellow.

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Borneol has an -OH group in a pseudo-axial position while the -OH group in isoborneol is pseudo-equatorial. When examining the product stability, the

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Introduction:- In organic chemistry the substitution reactions is the most important reactions, especially Nucleophilic aromatic substitution reactions where nucleophile attacks positive charge or partially positive charge As it does so, it replaces a weaker nucleophile which then becomes a leaving group. The remaining positive or partially positive atom becomes an electrophile. The general form of the reaction is: Nuc: + R-LG → R-Nuc + LG: The electron pair (:) from the nucleophile (Nuc :) attacks the substrate (R-LG) forming a new covalent bond Nuc-R-LG.

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Liquid-liquid extraction was used to isolate the arene solution before it was analyzed through GC. The relative reactivities of different arenes in electrophilic aromatic bromination was also observed. In this part, five different arenes were reacted with a solution of acetic acid and bromine and the rates of reaction—determined by a change in color—were recorded. These reactions were done with a water bath. 6.

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Bromination is the process where an alkene is halogenated with bromine. The purpose of this experiment was bromination of stilbene to stilbene dibromide. The element bromine is toxic and requires maximum care when used. Bromine was generated in the reaction mixture by using a green method. Less hazardous reagents were used to do so.

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Introduction of NMR spectroscopy Nuclear Magnetic Resonance (NMR) spectroscopy is a form of absorption spectroscopy by which a nuclei under investigation absorbs the energy from an external magnetic field and resonances or excites from a low energy state to a high energy state. It involves the disintegration of spin state into two spin states of unequal energy. The emerging radiofrequency is absorbed in a magnetic field resulting to the magnetic properties of the nuclei which getting up from the axial spin. Hence, different NMR absorption spectrum can be obtained which contains one to several groups of absorption lines in the radiofrequency part of the electromagnetic spectrum depends on the particular nucleus. Apparently, the location of peaks

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In this step of the organic synthesis, Intermediate 3 has formed. However, there is a tendency for this intermediate to form ester 4, which is a more stable carbonyl derivative. This is the case here as chlorine, which is a good leaving group, is attached to the carbon atoms that could form the carbonyl. This leaves ester 4 to form. 4.

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The objective of this lab was to determine the activating strengths of the directing groups in aniline, phenol, acetanilide and anisole by using melting point to identify the products of their electrophilic aromatic bromination reactions with pyridinium tribromide in glacial acetic acid. The amount of substitution in an aromatic compound in a electrophilic aromatic bromination reaction is dependent upon the reactivity of the aromatic compound itself, which is determined by its substituents’ inductive effects. In the case of this experiment, four different aromatic compounds were used, containing either -NH2, -OH, -OCH3, and -NHCOCH3 as substituents. Of these four, the most activating substituent is -NH2 in aniline because nitrogen is less electronegative than the oxygens in -OH and -OCH3 in phenol and

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Furthermore, the long-range 13C-1H correlation links those fragments to build the planar structure of the molecule under study. The homonuclear 2D 1H-1H COSY (correlation spectroscopy) experiment is used to identify the protons which are directly coupled to each other. The basic COSY-90 is the most widely used experiment while its minor variant COSY-45 sequence is acquired in order to distinguish geminal and vicinal proton pairs with less sensitivity than the previous one. Another significantly used experiment DEPT is to detect the proton

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A strong nucleophile/base will likely force a second order reaction because the nucleophile/base is strong enough to attack the electrophilic carbon. In this case, KOtBu is a strong, bulky base and -Br is a good leaving group. Although the Potassium is not crucial to this reaction, the t-butoxide will proceed to attack the single beta hydrogen and knock off bromide to form an alkene, rearranging the bromobutane into an anti-periplanar position. In the KOtBu and 1-bromobutane reaction, there is one beta hydrogen present; this means there is only one possible product, 1-butene. However, there are two different types of beta hydrogens present in 2-bromobutane.

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In this experiment rate of reaction with different reactants concentration: KI (0.010 M), KBrO3 (0.040 M), and HCl (0.10 M) will be observed. So, this is reaction between iodide and bromate ion under acidic conditions: 6 I- (aq) +BrO3-(aq)+ H+(aq)→ 3I2(aq) + Br-(aq)+ 3H2O The end of the reaction, will be determined by observing color change of solution. Thus, solution should shange color to blue.

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