Smith, Study Guide and Solutions Manual, McGraw Hill. Course Content: The course will cover common.
ORGANIC CHEMISTRY JANICE SMITH ANSWER KEY MANUAL
Student Study Guide/Solutions Manual by Janice G. Project: Chemistry LibreTexts.CEM 251: ORGANIC CHEMISTRY I TUTH 1:00 – 2:20, 138 CHEMISTRY FALL 2009 Provided by: Athabasca University Sonoma State University Michigan State U UCD Utah Valley University. Steven Farmer William Reusch, Professor Emeritus Mario Morataya Gamini Gunawardena.
16.10 Reduction of Aromatic Compounds. License: CC BY-NC-SA: Attribution-NonCommercial-ShareAlike Located at: (Smith)/Chapter_18%3A_Electrophilic_Aromatic_Substitution/18.4%3A_Nitration_and_Sulfonation. Located at: (McMurry)/Chapter_16%3A_Chemistry_of_Benzene_-_Electrophilic_Aromatic_Substitution/16.01_Electrophilic_Aromatic_Substitution_Reactions%3A_Bromination. Provided by: Athabasca University Sonoma State University Michigan State U. Steven Farmer Catherine Nguyen Wiliam Reusch, Professor Emeritus. 
16.1: Electrophilic Aromatic Substitution Reactions - Bromination. Located at: (Organic_Chemistry)/Arenes/Synthesis_of_Arenes/Electrophilic_Aromatic_Substitution. Synthesis of Benzene Derivatives: Electrophilic Aromatic Substitution. Located at: (Smith)/Chapter_18%3A_Electrophilic_Aromatic_Substitution/18.2%3A_The_General_Mechanism. Provided by: Sonoma State University, Michigan State U. Steven Farmer, William Reusch, Professor Emeritus. In principle it could react by either mode 1 or 2, but the energetic advantage of reforming an aromatic ring leads to exclusive reaction by mode 2 ( i.e., proton loss). The carbocation intermediate in electrophilic aromatic substitution (the Wheland intermediate) is stabilized by charge delocalization (resonance) so it is not subject to rearrangement. The second step of alkene addition reactions proceeds by the first mode, and any of these three reactions may exhibit molecular rearrangement if an initial unstable carbocation is formed. S N1 and E1 reactions are respective examples of the first two modes of reaction. The cation may rearrange to a more stable carbocation, and then react by mode #1 or #2. The cation may transfer a proton to a base, giving a double bond product (electrophile elimination).ģ. The cation may bond to a nucleophile to give a substitution or addition product (coordination).Ģ. To summarize, when carbocation intermediates are formed one can expect them to react further by one or more of the following modes:ġ. These include S N1 and E1 reactions of alkyl halides, and Brønsted acid addition reactions of alkenes. This mechanism for electrophilic aromatic substitution should be considered in context with other mechanisms involving carbocation intermediates. Step 1: Formation of the electrophile by reaction of Br 2 with FeBr 3. The mechanism (shown for bromination) is a typical EAS, comprising (1) electrophile activation (by coordination), then (2) electrophilic addition to form the Wheland intermediate, and finally (3) electrophile elimination to lose H +. However, since iron(III) halides are easily deactivated by water from the air, it is common to use iron metal powder, since this reacts easily with Cl 2 or Br 2 to form FeCl 3 or FeBr 3 respectively. Bromination and chlorinationĪ chlorine or bromine may be introduced using the element (Cl 2, Br 2) in the presence of the related iron(III) halide (FeCl 3 or FeBr 3) as the Lewis acid catalyst. 
The following examples of EAS, beginning with bromination, serve to illustrate how the reaction works in practice. These catalysts are always either Bronsted-Lowry acids or Lewis acids. Many electrophiles (such as Br 2) are not sufficiently electrophilic to react on their own, so many EAS reactions rely on a catalyst in order to activate the electrophile. The second step (electrophile addition) regenerates the aromatic system and it is a faster step. The Wheland intermediate is stabilized by resonance, but it is still much less stable than the starting material this loss of aromaticity means that the first step (electrophilic addition) is always the rate determining step in EAS. A detailed look at electrophilic aromatic substitution reactions (EAS)Īs outlined in the previous section, the basic mechanism for EAS involves electrophilic addition to form a non-aromatic Wheland intermediate, which then loses H+ through electrophile elimination.
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