Reminder: These notes are meant to supplement‚ not replace the laboratory manual. SN1 Reaction Notes Background and Application Substitution Nucleophilic First Order (SN1) reactions are one of the most common type of organic reactions. SN1 reactions can be used to make a wide variety of new compounds. In this experiment‚ t-amyl alcohol will be converted by a SN1 mechanism to 2-chloro-2-methylbutane. Safety Precautions Concentrated Hydrochloric Acid is 12M. It will cause visible destruction
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SN1 Reactions For SN1 reactions it’s important to have a good leaving group because this reaction occurs in two steps. Because alcohol is such a poor leaving group it needs to be helped by silver nitrate to help promote the ionization of the alkyl halide. This helps form the products of the SN1 reaction. 2-chlorobutane This reaction didn’t occur because the carbocation isn’t stable enough for an SN1 reaction. 2-bromobutane This reaction occurred in 32 seconds. This reaction occurred quickly
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1-butanol is SN2‚ and bromide is a better nucleophile. The first reason is that the substrate is a primary alcohol. The SN2 reaction is the nucleophilic attack of a central atom which kicks out the leaving group. A primary alcohol only has hydrogens plus the leaving group attached to the central carbon. Since the hydrogens do not hinder the nucleophilic attack‚ SN2 reaction is favored. The second reason is that bromide is a better nucleophile. Nucleophlicity is an essential factor in SN2 mechanism
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+ R’X R O R’ + NaX Ar O Na + RX Ar O R + NaX Involves a nucleophilic substitution reaction. Halide ion is displaced by the alkoxide or phenoxide ion. Gives best results when 1o alkyl halides are used. Mechanism is SN2. Alkoxides may be prepared by reacting an alcohol with NaH or by reacting an alcohol with Na metal. Phenoxides may be prepared by reaction of phenols with NaOH ROH + NaH ROH + Na ArOH + NaOH RO Na - - + + H2 RO Na + + 1/2
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The Wittig reaction is a unique reaction that can be carried out in various ways as our prompt exemplifies. We will be primary focusing on the second of the three schemes. In The usual formation of an ylide occurs via Sn2 attack of a PR3 group on an alkyl halide‚ which is then followed by a strong base deprotonating of one of the hydrogens on the methyl which the PR3 attacked. Before we dive into the details of the reaction occurring in scheme 2 it will be important to understand the mechanism which
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1 SN2 Reaction‚ Ionic Liquid (Group – hood) Background Reading Solomons and Fryhle Chapter 6 (Substitution/Elimination Reactions) Techniques: Weights and Measures‚ Reflux‚ Liquid-Liquid Extraction‚ Distillation. Introduction The SN2 reaction is a bimolecular nucleophilic substitution reaction where the nucleophile (a molecule with a free pair of electrons) reacts with an alkyl halide and replaces the halogen (for more details see Solomons and Fryle‚ Chapter 6). The nucleophile approaches
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acetone and silver nitrate in ethanol. Below the reaction equations 1. RX+NAIRI+NAX (X=Cl or Br) in the presence of acetone 2. RX+AgNO3+EtOHROEt+AgX+HNO3 We used three substrates primary secondary and tertiary compounds are 1-bromobutane‚ 2-bromobutane and 2-bromo-2-methylpropane respectively to react with the two nucleophiles that are sodium iodide with acetone solvent and silver nitrate with ethanol solvent. Based on lab analysis and the reaction mechanism we can predict the reactivities of the
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Title: Relativities of Alkyl Halides in Nucleophilic Substitution Reactions Introduction: The purpose of this lab was to perform a comparison of relative reactivities of various alkyl halides with two different reagents‚ sodium iodine in acetone and silver nitrate in ethanol. (Below are the reaction equations). We used different substrates‚ which were primary‚ secondary‚ and tertiary. These substrates included 2-bromobutane‚ 2-bromo-2-methylpropane‚ 1-bromobutane ∞-Bromotoluene‚ bromobenzene
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Elimination Reactions ________________________________________ As described previously‚ primary alkyl halides generally undergo substitution reactions with simple nucleophiles by an SN2 mechanism. Secondary alkyl halides‚ often react with simple basic nucleophiles to give a mixture of products arising from both substitution and elimination. As with substitution reactions‚ the rate at which elimination reactions proceed can be proportional to both the concentration of the base and the concentration
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of tert-Butyl Chloride Via an SN1 Reaction Introduction/Background: Alkyl halides are compounds in which a halogen atom replaces a hydrogen atom of an alkane. Alkyl halides are classified as primary‚ secondary or tertiary depending on the number of alkyl substituents directly attached to the carbon attached to the halogen atom. The purpose of this lab was to properly prepare t-butyl chloride from t-butyl-alcohol in a concentrated hydrochloric acid. The reaction occurs through a nucleophilic substitution
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