.This experiment was performed to determine the structure of alkyl-halides formed as a result of substitution reactions, and whether the reaction used an SN1 or SN2 mechanism. The structure of the starting alcohol determined the mechanistic pathway of the substitution reaction. Reaction 1 involved the substitution of a primary alcohol which produced one primary alkyl-halide via SN2 reaction. Reactions 2 and 3 began with a secondary alcohol, forming two products as the result of direct substitution and/or a hydride shift, via SN1 reaction. Reaction 2 formed two secondary alkyl-halides, and Reaction 3 formed one secondary and one tertiary alkyl-halide. The overall premise of the various experiments chronicled in this article is the determination of the mechanistic pathways and products formed via substitution reactions. Substitution reactions occur when one atom or functional group replaces another. For the purposes of this experiment, there were two types of substitution reactions: SN1 or unimolecular nucleophilic substitution, 1st order and SN2 or bimolecular nucleophilic substitution, 2nd order. 1 Substitution reactions, whether they are an SN1 or SN2 reaction, must contain molecules known as nucleophiles and electrophiles. The electrophile is a component of the substrate, in this case the starting alcohol, also commonly known as the “leaving group.” Electrophiles are electron deficient, while nucleophiles are “electron donating.” The mechanism of a substitution reaction is as follows: in the presence of the nucleophile, the leaving group separates from the substrate allowing the nucleophile to form a new bond with the substrate in place of the recently departed electrophile. 2 The key difference between the SN1 and SN2 me... ... middle of paper ... ...lpentane. 1H NMR (CDCl3, 200 MHz) δ 2.1-1.8 (nonet, 1H), 1.7 (d, 6H), 1.6 (s, 6H), 0.95-0.90 (d, 2H). 3-chloro-2,4-dimethylpentane. 1H NMR (CDCl3, 200 MHz) δ 3.6-3.5 (t, 1H), 2.6-2.4(octet, 2H) 1.1-1.0 (d, 12H). IR (cm-1) 2962.42, 743.14, 708.01. GC (TCD) 4.2 m (100%). Acknowledgements. Special thanks go to the Department of Chemistry and Chemical Biology at IUPUI, Dr. Ryan E. Denton, Professor and Dan Preston, TA. References. 4 1. Denton, R.E.; Audu, C. “Investigating Substitution Reactions of Various Alcoholic Compounds.” Fake Journal of Organic Chemistry 2010, 77, 3452-3453. 2. Klein, David. Organic Chemistry. Hoboken: John Wiley & Sons, Inc., 2012. Print 3. Balasubramanian, Satish. ChemWiki. University of California, Davis, (n.d.). Web. 29 APR 2014. 4. The Purdue Online Writing Lab. The Writing Lab and OWL at Purdue University, 2008. Web. 29 Apr. 2014.
The purpose of this lab was to perform an electro-philic aromatic substitution and determine the identity of the major product. TLC was used to detect unre-acted starting material or isomeric products present in the reaction mixture.
Wittig reactions allow the generation of an alkene from the reaction between an aldehyde/ketone and a ylide (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) 4 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. The positive charge on the phosphorus atom is a strong EWG (electron-withdrawing group), which will trigger the adjacent carbon as a weak acid 5 Very strong bases are required for deprotonation such as an alkyl lithium however in this experiment 50% sodium hydroxide was used as reiterated. Lastly, the reaction between ylide and aldehyde/ketone produces an alkene.3
Step 5: An intramolecular SNAr reaction of the enamine takes place resulting in a cyclised quinolone (20). This is formed in basic conditions using a base such as NaH or KH.
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.
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 objective of this experiment was to conduct the Friedel-Crafts Alkylation of p-xylene. This reaction substituted an alkyl group instead of a hydrogen atom on the aromatic ring. The compound used was p-xylene, the reactant was n-propyl chloride, and the Lewis acid catalyst was aluminum chloride. The products consisted of the group of n-propyl that combined with p-xylene to form 1,4 Dimethyl-2-propylbenzene, and the group of isopropyl that combined with p-xylene to form 2-isopropyl-1,4-dimethylbenzene
The article, “Asymmetric one-pot Robinson annulations” (Rajagopal et al., 2001) describes the procedure of a Robinson Annulation Reaction that converts a five-membered cyclic ketone to a two-ring, bicyclic compound. In this reaction, 1.12 g of 0.01 mol dione was added to a solution of 1.15 g of 0.01 mol S-proline in dry DMSO and mixed in a beaker, followed by 0.7 g of 0.01 mol methyl vinyl ketone. This mixture was stirred for 145 ...
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
Single Replacement is the process of an element reacting with a compound and taking the place of another element. Substance C can take the place of Substance A in the compound of AB. A metal can only replace a metal and a nonmetal can only replace a nonmetal. To predict whether or not the reaction will occur, using an activity series table will help to compare the reactivities of the elements. The reactivity of a metals is based more on the electronegativity making it more difficult to predict the reactivity of the halogens. A real life example is in the Statue of Liberty, the inside structure was made out of steel. The iron in steel reacts with the oxidized copper which protects the color and integrity. The formula for this reaction is Fe + Cu2+ → Fe2+ + Cu. In a lab 17 single replacements reactions were tested however not all had a reaction. Some were quicker and some slower to react compared to others due to different reaction rates in each
23. S. Alwarappan, S. Boyapalle, A. Kumar, C.-Z. Li and S. Mohapatra, J. Phys. Chem. C, 2012, 116, 6556–6559
Sn(Oct)2 reacts with hydroxide groups of another compounds added or present in the reaction and formed the actual initiator, tin(II) alkoxide or hydroxide.
Plontke, R. (2003, March 13). Chemnitz UT. TU Chemnitz: - Technische Universität Chemnitz. Retrieved April 1, 2014, from http://www.tu-chemnitz.de/en/
Predictions may be made about the suitability of possible catalysts by assuming that the mechanism of catalysis consists of two stages, either of which can be first: