Finkelstein reaction
The Finkelstein reaction is a biomolecular nucleophilic substitution reaction (SN2) and is an example of a halide exchange reaction.1 The reaction was named after the German scientist, Hans Finkelstein, and was published in a journal in 1910.2 The usual Finkelstein reaction consists of the halogen atom on either an alkyl chloride or alkyl bromide being replaced by an iodine atom to form an alkyl iodide. The solvent and halide salt typically utilised are acetone and sodium iodide, this is since both the alkyl halides, formed as the product and used as the reactant, are soluble in acetone as well as the sodium iodide also being soluble in this solvent.3
Reaction scheme
Although this reaction is referred to as an equilibrium
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Primary alkyl halides are the most suitable to undergo this reaction, followed by secondary alkyl halides but tertiary alkyl halides are rather unreactive.4The readiness of the alkyl halide to undergo the Finkelstein reaction affects the rate of the reaction, as primary alkyl halides have the fastest rate and secondary being second fastest. The unreactive nature of tertiary alkyl halides leads to a slight different pathway, as the reaction occurs in unimolecular nucleophilic substitution manner (SN1) as steric hinderance plays a part in not allowing the SN2 route.5There are more variables that can influence the rate of the Finkelstein reaction such as the use of other solvents, the halide being displaced, the length of the carbon chain in the alkyl group and the type of halide such as benzyl …show more content…
The detection of hydrogen atom resonances is possible since the isotope has a spin of half.6 An external magnetic field is applied to the sample, promoting the nuclei to a higher energy level. Once the nuclei return to their original energy levels, energy is emitted which is measured helping to build up a spectrum. Samples used for this type of spectroscopy are usually in solution form by dissolving the desired substance in a solvent. The type of solvent used must be deuterated or not contain hydrogen atoms as a solvent proton peak could obstruct the solution solvent peak, examples of solvents that could be used are deuterated acetone and deuterated chloroform. Tetramethylsilane (TMS) is commonly used as an internal standard to calibrate the spectrum due to its sharp single peak caused by its twelve chemically equivalent hydrogens and its assigned chemical shift which is
As a final point, the unknown secondary alcohol α-methyl-2-naphthalenemethanol had the R-configuration since it reacted the fastest with S-HBTM and much slower with R-HBTM. TLC was a qualitative method and ImageJ served as a quantitative method for determining which reaction was the faster esterification. Finally, 1H NMR assisted in identifying the unknown from a finite list of possible alcohols by labeling the hydrogens to the corresponding peaks.
There are two types of reactions that can take place in this lab, E1, unimolecular elimination, and E2, bimolecular elimination. An E1
Enantiomers, a type of isomer, are non-superimposable, mirror images of each other. Diasteriomers, another type of isomer, are non-superimposable, non-mirror images of each other. Dimethyl maleate and dimethyl fumarate are diasteriomers, as they are not mirror images but instead vary in the orientation of the carbomethoxy groups around the double bond. Dimethyl maleate is the cis-isomer because both groups are on the same side and dimethyl fumarate is the trans-isomer because the two groups are on opposite sides. A bromine free radical mechanism was required for this conversion. First, energy from light is required to create two bromine free radicals from Br2. Then one of the free radicals attacks the double bond in dimethyl maleate, breaking it and creating a carbon radical on the other carbon. The bond then rotates and reforms, freeing the bromine radical and creating the trans-isomer, dimethyl fumarate. Bromine in this reaction is acting as a catalyst in this reaction and then cyclohexane is added at the end to neutralize the bromine free radicals. The activation reaction of the radical reaction is lower than the activation energy of the addition reaction, which is why it occurred more quickly. This reaction was successful because the percent yield was 67.1%, which is greater that 65%. It also demonstrated the expected principles, as the reaction did not occur without the presence of both light and bromine. The dimethyl fumarate had a measured boiling point of 100C to 103C, which is extremely close to the expected boiling point of 102C to
Wittig reactions allow the generation of an alkene from the reaction between an aldehyde/ketone and an alkyl halide (derived from phosphonium salt).The mechanism for the synthesis of trans-9-(2-phenylethenyl) anthracene first requires the formation of the phosphonium salt by the addition of triphenylphosphine and alkyl halide. The phosphonium halide is produced through the nucleophilic substitution of 1° and 2° alkyl halides and triphenylphosphine (the nucleophile and weak base). An example is benzyltriphenylphosphonium chloride, which was used in this experiment. The second step in the formation of the of the Wittig reagent, which is primarily called a ylide and derived from a phosphonium halide. In the formation of the ylide, the phosphonium ion in benzyltriphenylphosphonium chloride is deprotonated by the base, sodium hydroxide to produce the ylide as shown in equation 1.
Discussion and Conclusions: Interpreting these results have concluded that relative reactivity of these three anilines in order of most reactive to least reactive go; Aniline > Anisole > Acetanilide. Aniline, has an NH2 , the most active substituent , and adds to any ortho/para position available on the ring. This data is confirmed with the product obtained, (2,4,6 tribromoaniline, mp of 108-110 C). As for anisole, it has a strongly activating group attached, OMe an alkoxy group, and it added in two of the three available spots, both ortho. The results conclude: (2,4-Dibromoanisol mp 55-58 C ). Acetanilide has a strong activating group attached, acylamino group, but this group is large and the ortho positions are somewhat hindered so the majority of the product obtained added at the para position, results conclude: (p-bromoacetanilide mp 160-165 C). Since all the substituents attached to the aromatic rings were activators the only products able to be obtained were ortho/para products.
Discussion The reaction of (-)-α-phellandrene, 1, and maleic anhydride, 2, gave a Diels-Alder adduct, 4,7-ethanoisobenzofuran-1,3-dione, 3a,4,7,7a-tetrahydro-5-methyl-8-(1-methylethyl), 3, this reaction gave white crystals in a yield of 2.64 g (37.56%). Both hydrogen and carbon NMR as well as NOESY, COSY and HSQC spectrum were used to prove that 3 had formed. These spectroscopic techniques also aided in the identification of whether the process was attack via the top of bottom face, as well as if this reaction was via the endo or exo process. These possible attacks give rise to four possible products, however, in reality due to steric interactions and electronics only one product is formed.
This experiment was divided into two main steps. The first step was the addition of bromine to trans-stilbene. Trans-stilbene was weighted out 2.00g, 0.0111mol and mixed with 40ml of glacial acetic acid in 100ml Erlenmeyer flask on a hot bath. Pyridinium hydrobromide perbromide of 4.00g, 0.0125mol was added carefully into the flask.
The product was recrystallized to purify it and the unknown filtrate and nucleophile was determined by taking the melting points and performing TLC. Nucleophilic substitution reactions have a nucleophile (electron pair donor) and an sp3 electrophile (electron pair acceptor) with an attached leaving group. This experiment was a Williamson ether synthesis usually SN2, with an alkoxide and an alkyl halide. Conditions are favored with a strong nucleophile, good leaving group, and a polar aprotic solvent.
The weight of the final product was 0.979 grams. A nucleophile is an atom or molecule that wants to donate a pair of electrons. An electrophile is an atom or molecule that wants to accept a pair of electrons. In this reaction, the carboxylic acid (m-Toluic acid), is converted into an acyl chlorosulfite intermediate. The chlorosulfite intermediate reacts with a HCL. This yields an acid chloride (m-Toluyl chloride). Then diethylamine reacts with the acid chloride and this yields N,N-Diethyl-m-Toluamide.
Purpose/Introduction: In this experiment, four elimination reactions were compared and contrasted under acidic (H2SO4) and basic (KOC(CO3)3) conditions. Acid-catalyzed dehydration was done on 2-butanol and 1-butanol; a 2o and 1o alcohol, respectively. The base-induced dehydrobromination was performed on 2-bromobutane and 1-bromobutane isomeric halides. The stereochemistry and regiochemistry of the four reactions were analyzed by gas chromatography (GC) to determine product distribution (assuming that the amount of each product in the gas mixture is proportional to the area under its complementary GC peak).
Radiometric dating is the process of determining the age of a substance based on the ratio of isotopes in a given sample. The number of protons in the nucleus of an atom defines a particular element. However, the number of neutrons in the nucleus can vary, giving rise to different isotopes of the same element. Some of these isotopes are stable, while others are not. These unstable isotopes radioactively decay to more stable, often lighter elements, called daughter atoms, thereby releasing energy in the form of high-energy particles or electromagnetic waves.
...and around the sides, generated by a powerful cryogenic electromagnet. Spinning protons, forming the nucleus of hydrogen atoms, have magnetic properties causing the protons in the body to align with the magnetic field in the same direction. We know from Ball and Moore (2008) that hydrogen is found in great volume in body tissues. The protons, exposed to short pulses of radiofrequency, disturb the alignment and cause the protons to flip from longitudinal to transverse plane. When hydrogen protons re-align and relax back to their original position they emit a small, weak radio signal, which is detected by either an antenna or coil. The radio signals are analysed by a computer, determining spatial distribution and chemical bonds of hydrogen atom. This generates an image, displayed as a two-dimensional grey-scale slice image.(Easton, 2009; Ball and Price, 1995)
The aim of this experiment was to investigate the affect of the use of a catalyst and temperature on the rate of reaction while keeping all the other factors that affect the reaction rate constant.
In terms of the electromagnetic spectrum, radio waves are slightly longer than infrared in the wide range of 10-2m to 105m, corresponding to frequencies from 300 GHz to as low as 3 kHz. The application of radio waves in imaging comes from the concept of nuclear magnetic resonance (NMR). NMR, a physical phenomenon utilized to investigate the molecular properties of matter with the use of the absorption of electromagnetic energy, is similar to VHF and UHF television broadcasts (60–1000 MHz) by the placing of atomic nuclei in a strong magnetic field. This concept can be implemented on many different scientific studies such as medical imaging. Since NMR does not have any harmful side effects on humans it has seen an increase in laboratory use. Commonly used NMR applications in contaminant transport imaging and environmental studies are discussed below.
The proton precession magnetometer is so named because it utilizes the precession of spinning protons or nuclei of the hydrogen atom in a sample of hydrocarbon fluid to measure the total magnetic intensity. The sensor component is a cylindrical container filled with a liquid rich in hydrogen atoms surrounded by a coil.kerosene, alcohol and water are the commonly liquids used. On closing the switch a DC current from the battery is directed through the coil, producing a relatively strong magnetic field in the fluid filled cylinder. The hydrogen nuclei (protons) behave like minute spinning dipole magnets ,become aligned along the direction of the applied field(i.e along the axis of the cylinder).