{"id":1059,"date":"2017-10-19T14:18:44","date_gmt":"2017-10-19T14:18:44","guid":{"rendered":"https:\/\/courses.lumenlearning.com\/suny-mcc-organicchemistry\/?post_type=chapter&#038;p=1059"},"modified":"2018-10-03T20:11:27","modified_gmt":"2018-10-03T20:11:27","slug":"halogenation-of-alkenes","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/suny-mcc-organicchemistry\/chapter\/halogenation-of-alkenes\/","title":{"raw":"Halogenation of Alkenes","rendered":"Halogenation of Alkenes"},"content":{"raw":"<div class=\"elm-header\">\r\n<div class=\"elm-header-custom\">\r\n<div class=\"textbox learning-objectives\">\r\n<h3>Objectives<\/h3>\r\n<div class=\"elm-header\"><\/div>\r\n<div id=\"elm-main-content\" class=\"elm-content-container\">\r\n<div>\r\n<div id=\"skills\">\r\n\r\nAfter completing this section, you should be able to\r\n<ol>\r\n \t<li>write the equation for the reaction of chlorine or bromine with a given alkene.<\/li>\r\n \t<li>identify the conditions under which an addition reaction occurs between an alkene and chlorine or bromine.<\/li>\r\n \t<li>draw the structure of the product formed when a given alkene undergoes an addition reaction with chlorine or bromine.<\/li>\r\n \t<li>write the mechanism for the addition reaction that occurs between an alkene and chlorine or bromine, and account for the stereochemistry of the product.<\/li>\r\n<\/ol>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div class=\"textbox key-takeaways\">\r\n<h3>Key TERMS<\/h3>\r\n<div id=\"elm-main-content\" class=\"elm-content-container\">\r\n<div>\r\n<div>\r\n\r\nMake certain that you can define, and use in context, the key terms below.\r\n<ul>\r\n \t<li>anti stereochemistry<\/li>\r\n \t<li>bromonium ion<\/li>\r\n<\/ul>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div class=\"textbox\">\r\n<div id=\"elm-main-content\" class=\"elm-content-container\">\r\n<div id=\"note\">\r\n<h3 class=\"boxtitle\">Study Notes<\/h3>\r\nIn the laboratory you will test a number of compounds for the presence of a carbon-carbon double bond. A common test is the decolourization of a reddish-brown bromine solution by an alkene.\r\n\r\nThe two-step mechanism shown in the LibreText pages gives you an idea of how the reaction between an alkene and a halogen occurs. Note the formation of the bridged bromonium ion intermediate and the anti stereochemistry of the final product because the two bromine atoms come from opposite faces of the double bond.\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"435\"]<img src=\"http:\/\/chem.libretexts.org\/@api\/deki\/files\/84935\/8-2.png?origin=mt-web\" alt=\"bromination of cyclopentene\" width=\"435\" height=\"91\" \/> Figure 8.2: Reaction of an alkene with bromine in the presence of sodium chloride[\/caption]\r\n\r\nAdditional evidence in support of the bromonium ion mechanism comes from the results obtained when an alkene (such as cyclopentene) reacts with bromine in the presence of sodium chloride (see Figure\u00a08.2: Reaction of an alkene with bromine in the presence of sodium chloride, below).\r\n\r\n<\/div>\r\n<div id=\"note\">\r\n\r\nOnce formed, the bromonium ion is susceptible to attack by two nucleophiles\u2014chloride ion and bromide ion\u2014and, in fact, a mixture of two products (both produced by anti attack) is formed.\r\n\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div id=\"elm-main-content\" class=\"elm-content-container\">\r\n\r\nHalogens can act as <a class=\"internal mt-disabled\" title=\"Wikitexts\/UCD Chem 118A\/ChemWiki Module Topics for Chem 118B\/Acids and Bases; Electrophiles and Nucleophiles\" rel=\"broken\">electrophiles<\/a> to attack a double bond in <span class=\"internal\">alkene<\/span>. Double bond represents a region of electron density and therefore functions as a <a class=\"internal mt-disabled\" title=\"Wikitexts\/UCD Chem 118A\/ChemWiki Module Topics for Chem 118B\/Acids and Bases; Electrophiles and Nucleophiles\" rel=\"broken\">nucleophile<\/a>.\u00a0How is it possible for a halogen to obtain positive charge to be an electrophile?\r\n<div id=\"section_1\">\r\n<h3 class=\"editable\">Introduction<\/h3>\r\nAs halogen molecule, for example Br<sub>2<\/sub><sub>,<\/sub> approaches a double bond of the alkene, electrons in the double bond\u00a0 repel electrons in bromine molecule causing polarization of the halogen bond. This creates a dipolar moment in the halogen molecule bond. Heterolytic bond cleavage occurs and one of the halogens obtains positive charge and reacts as an electrophile. The reaction of the addition is not regioselective but stereoselective.Stereochemistry of this addition can be explained by the mechanism of the reaction.In the first step electrophilic halogen with a positive charge approaches\u00a0 the double carbon bond and 2 p orbitals of the halogen, bond with two carbon atoms and create a cyclic ion\u00a0 with a halogen as the intermediate step. In the second step, halogen with the negative charge attacks any of the two carbons in the cyclic ion from the\u00a0 back side of the cycle as in the <a title=\"SN2 reactions\" href=\"https:\/\/chem.libretexts.org\/Core\/Physical_and_Theoretical_Chemistry\/Kinetics\/Rate_Laws\/Gas_Phase_Kinetics\/Bimolecular_SN2_Reactions\/SN2_reactions\" rel=\"internal\"><span class=\"internal\">S<sub>N<\/sub>2 reaction<\/span><\/a>. Therefore stereochemistry of the product is vicinial dihalides through <strong>anti<\/strong> addition.\r\n\r\n\\[\\ce{R_2C=CR_2\u00a0\u00a0 +\u00a0 X_2\u00a0\u00a0 \\rightarrow\u00a0 R_2CX-CR_2X} \\tag{8.2.1}\\]\r\n\r\nHalogens that are commonly used in this type of the reaction are: $$Br$$ and $$Cl$$. In thermodynamical terms $$I$$ is too slow for this reaction because of the size of its atom, and $$F$$ is too vigorous and explosive. Solvents that are used for this type of electrophilic halogenation are inert (e.g., CCl<sub>4<\/sub>) can be used in this reaction.\r\n\r\nBecause halogen with negative charge can attack any\u00a0 carbon from the opposite side of the cycle it creates a mixture of steric products.Optically inactive starting material produce optically inactive achiral products (<a class=\"internal\" title=\"Organic Chemistry\/Chirality\/Meso Compounds\" href=\"https:\/\/chem.libretexts.org\/Core\/Organic_Chemistry\/Chirality\/Meso_Compounds\" rel=\"internal\">meso<\/a>) or a <a title=\"Resolution of Racemates\" href=\"https:\/\/chem.libretexts.org\/Core\/Organic_Chemistry\/Chirality\/Stereoisomers\/Chirality_and_Symmetry\/Enantiomorphism\/Resolution_of_Racemates\" rel=\"internal\"><span class=\"internal\">racemic mixture<\/span><\/a>.\r\n\r\n<\/div>\r\n<div id=\"section_2\">\r\n<h3 class=\"editable\">Electrophilic addition mechanism consists of two steps.<\/h3>\r\nBefore constructing the mechanism let us summarize conditions for this reaction. We will use Br<sub>2<\/sub> in our example for halogenation of ethylene.\r\n<table style=\"border-spacing: 1px;width: 281px\" border=\"1\" cellpadding=\"1\">\r\n<tbody>\r\n<tr>\r\n<td><strong>Nucleophile<\/strong><\/td>\r\n<td><strong>Double bond in alkene<\/strong><\/td>\r\n<\/tr>\r\n<tr>\r\n<td>Electrophile<\/td>\r\n<td>Br<sub>2<\/sub><sub>,<\/sub>\u00a0Cl<sub>2<\/sub><\/td>\r\n<\/tr>\r\n<tr>\r\n<td><strong>Regio<\/strong>chemistry<\/td>\r\n<td>not relevant<\/td>\r\n<\/tr>\r\n<tr>\r\n<td><strong>Stereo<\/strong>chemistry<\/td>\r\n<td><strong>\u00a0\u00a0ANTI<\/strong><\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\nStep 1: In the first step of the addition the Br-Br bond polarizes, heterolytic cleavage occurs and Br with the positive charge forms a intermediate cycle with the double bond.\r\n\r\n<img class=\"internal default aligncenter\" src=\"https:\/\/chem.libretexts.org\/@api\/deki\/files\/2030\/Mechanism1.bmp?revision=1&amp;size=bestfit&amp;width=360&amp;height=150#fixme\" alt=\"Mechanism1.bmp\" width=\"360px\" height=\"150px\" \/>\r\n\r\nStep 2: In the second step, bromide anion attacks any carbon of the bridged bromonium ion from the back side of the cycle. Cycle opens up and two halogens are in the position <strong>anti<\/strong>.\r\n\r\n<img class=\"internal default aligncenter\" src=\"https:\/\/chem.libretexts.org\/@api\/deki\/files\/2028\/Mechanism_2_a.bmp?revision=1&amp;size=bestfit&amp;width=337&amp;height=128#fixme\" alt=\"Mechanism 2 a.bmp\" width=\"337px\" height=\"128px\" \/>\r\n\r\n<\/div>\r\n<div id=\"section_3\">\r\n<h3 class=\"editable\">Summary<\/h3>\r\nHallogens can act as electrophiles due to polarizability of their covalent bond.Addition of halogens is stereospecific and produces vicinial dihalides with anti addition.Cis starting material will give mixture of enantiomers and trans produces a meso compound.\r\n\r\n<\/div>\r\n<div id=\"section_4\">\r\n<h3 class=\"editable\">References<\/h3>\r\n<ol>\r\n \t<li>Vollhard,K.Peter C., and Neil E.Schore.<u>Organic Chemistry:Structure and Function.<\/u>New Yourk: W.H.Freeman and Company 2007<\/li>\r\n \t<li><u>Chemestry-A Europian Journal<\/u> 9 (2003) :1036-1044<\/li>\r\n<\/ol>\r\n<\/div>\r\n<div id=\"section_5\">\r\n<div class=\"textbox examples\">\r\n<h3>Examples<\/h3>\r\n<h3 class=\"editable\">Problems<\/h3>\r\n1.What is the mechanism of adding Cl<sub>2<\/sub> to the cyclohexene?\r\n\r\n<img class=\"internal default aligncenter\" src=\"https:\/\/chem.libretexts.org\/@api\/deki\/files\/2022\/Chem2.bmp?revision=1&amp;size=bestfit&amp;width=268&amp;height=74#fixme\" alt=\"Chem2.bmp\" width=\"268px\" height=\"74px\" \/>\r\n\r\n2.A reaction of Br<sub>2<\/sub> molecule in an inert solvent with alkene follows?\r\n\r\na) syn addition\r\n\r\nb) anti addition\r\n\r\nc) Morkovnikov rule\r\n\r\n3)<img class=\"internal default\" src=\"https:\/\/chem.libretexts.org\/@api\/deki\/files\/2023\/Chem5_Q.bmp?revision=1&amp;size=bestfit&amp;width=221&amp;height=45#fixme\" alt=\"Chem5 Q.bmp\" width=\"221px\" height=\"45px\" \/>\r\n\r\n4)<img class=\"internal default\" src=\"https:\/\/chem.libretexts.org\/@api\/deki\/files\/2020\/Chem_5_Q.bmp?revision=1&amp;size=bestfit&amp;width=167&amp;height=48#fixme\" alt=\"Chem 5 Q.bmp\" width=\"167px\" height=\"48px\" \/>\r\n<h3>ANSWERS<\/h3>\r\n[reveal-answer q=\"495877\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"495877\"]\r\n\r\n1.\r\n\r\n<img class=\"internal aligncenter\" src=\"https:\/\/chem.libretexts.org\/@api\/deki\/files\/2027\/Choloro__problem_2.bmp?revision=1&amp;size=bestfit&amp;width=697&amp;height=181#fixme\" alt=\"Choloro problem 2.bmp\" width=\"697px\" height=\"181px\" \/>\r\n\r\n2.\u00a0b\r\n\r\n3.<img class=\"internal default aligncenter\" src=\"https:\/\/chem.libretexts.org\/@api\/deki\/files\/2021\/Chem_exampl_4.bmp?revision=1&amp;size=bestfit&amp;width=349&amp;height=92#fixme\" alt=\"Chem exampl 4.bmp\" width=\"349px\" height=\"92px\" \/>enantiomer\r\n\r\n4.<img class=\"internal default aligncenter\" src=\"https:\/\/chem.libretexts.org\/@api\/deki\/files\/2024\/Chemestry_problem_4.bmp?revision=1&amp;size=bestfit&amp;width=278&amp;height=54#fixme\" alt=\"Chemestry problem 4.bmp\" width=\"278px\" height=\"54px\" \/>[\/hidden-answer]\r\n\r\n<\/div>\r\n<\/div>\r\n<div id=\"section_6\">\r\n<div class=\"textbox exercises\">\r\n<h3 class=\"editable\">Exercises<\/h3>\r\n<div id=\"s61713\">\r\n<div id=\"section_8\">\r\n<h3 id=\"Questions-61713\">Questions<\/h3>\r\n<strong>1.<\/strong>\r\n\r\nPredict the product of the product of 1,2-dimethylcyclopentene reacting with Br<sub>2<\/sub> with proper stereochemistry.\r\n\r\n<strong>2.<\/strong>\r\n\r\nPredict the products for 1,2-dimethylcyclpentene reacting with HCl, give the proper stereochemistry. What is the relationship between the two products?\r\n\r\n<\/div>\r\n<div id=\"section_9\">\r\n<h3 id=\"Solutions-61713\">Solutions<\/h3>\r\n<strong>\r\n[reveal-answer q=\"991501\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"991501\"]1.<\/strong>\r\n\r\n<img class=\"internal default aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1518\/2017\/10\/05141559\/8.2.png\" alt=\"\" width=\"146\" height=\"160\" \/>\r\n\r\n<strong>2.<\/strong>\r\n\r\n<img class=\"internal default aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1518\/2017\/10\/05141601\/8.22.png\" alt=\"\" width=\"343\" height=\"145\" \/>\r\n\r\nThese compounds are enantiomers<strong>[\/hidden-answer]<\/strong>\r\n\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div id=\"section_7\">\r\n<h3 class=\"editable\">Contributors<\/h3>\r\n<ul>\r\n \t<li><a class=\"external\" title=\"http:\/\/science.athabascau.ca\/staff-pages\/dietmark\" href=\"http:\/\/science.athabascau.ca\/staff-pages\/dietmark\" target=\"_blank\" rel=\"external nofollow noopener\">Dr. Dietmar Kennepohl<\/a> FCIC (Professor of Chemistry, <a class=\"external\" title=\"http:\/\/www.athabascau.ca\/\" href=\"http:\/\/www.athabascau.ca\/\" target=\"_blank\" rel=\"external nofollow noopener\">Athabasca University<\/a>)<\/li>\r\n \t<li>Prof. Steven Farmer (<a class=\"external\" title=\"http:\/\/www.sonoma.edu\" href=\"http:\/\/www.sonoma.edu\" target=\"_blank\" rel=\"external nofollow noopener\">Sonoma State University<\/a>)<\/li>\r\n \t<li>Jim Clark (<a class=\"external\" title=\"http:\/\/www.chemguide.co.uk\" href=\"http:\/\/www.chemguide.co.uk\" target=\"_blank\" rel=\"external nofollow noopener\">Chemguide.co.uk<\/a>)<\/li>\r\n<\/ul>\r\n<\/div>\r\n<\/div>","rendered":"<div class=\"elm-header\">\n<div class=\"elm-header-custom\">\n<div class=\"textbox learning-objectives\">\n<h3>Objectives<\/h3>\n<div class=\"elm-header\"><\/div>\n<div id=\"elm-main-content\" class=\"elm-content-container\">\n<div>\n<div id=\"skills\">\n<p>After completing this section, you should be able to<\/p>\n<ol>\n<li>write the equation for the reaction of chlorine or bromine with a given alkene.<\/li>\n<li>identify the conditions under which an addition reaction occurs between an alkene and chlorine or bromine.<\/li>\n<li>draw the structure of the product formed when a given alkene undergoes an addition reaction with chlorine or bromine.<\/li>\n<li>write the mechanism for the addition reaction that occurs between an alkene and chlorine or bromine, and account for the stereochemistry of the product.<\/li>\n<\/ol>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<div class=\"textbox key-takeaways\">\n<h3>Key TERMS<\/h3>\n<div id=\"elm-main-content\" class=\"elm-content-container\">\n<div>\n<div>\n<p>Make certain that you can define, and use in context, the key terms below.<\/p>\n<ul>\n<li>anti stereochemistry<\/li>\n<li>bromonium ion<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<div class=\"textbox\">\n<div id=\"elm-main-content\" class=\"elm-content-container\">\n<div id=\"note\">\n<h3 class=\"boxtitle\">Study Notes<\/h3>\n<p>In the laboratory you will test a number of compounds for the presence of a carbon-carbon double bond. A common test is the decolourization of a reddish-brown bromine solution by an alkene.<\/p>\n<p>The two-step mechanism shown in the LibreText pages gives you an idea of how the reaction between an alkene and a halogen occurs. Note the formation of the bridged bromonium ion intermediate and the anti stereochemistry of the final product because the two bromine atoms come from opposite faces of the double bond.<\/p>\n<div style=\"width: 445px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/chem.libretexts.org\/@api\/deki\/files\/84935\/8-2.png?origin=mt-web\" alt=\"bromination of cyclopentene\" width=\"435\" height=\"91\" \/><\/p>\n<p class=\"wp-caption-text\">Figure 8.2: Reaction of an alkene with bromine in the presence of sodium chloride<\/p>\n<\/div>\n<p>Additional evidence in support of the bromonium ion mechanism comes from the results obtained when an alkene (such as cyclopentene) reacts with bromine in the presence of sodium chloride (see Figure\u00a08.2: Reaction of an alkene with bromine in the presence of sodium chloride, below).<\/p>\n<\/div>\n<div id=\"note\">\n<p>Once formed, the bromonium ion is susceptible to attack by two nucleophiles\u2014chloride ion and bromide ion\u2014and, in fact, a mixture of two products (both produced by anti attack) is formed.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<div id=\"elm-main-content\" class=\"elm-content-container\">\n<p>Halogens can act as <a class=\"internal mt-disabled\" title=\"Wikitexts\/UCD Chem 118A\/ChemWiki Module Topics for Chem 118B\/Acids and Bases; Electrophiles and Nucleophiles\" rel=\"broken\">electrophiles<\/a> to attack a double bond in <span class=\"internal\">alkene<\/span>. Double bond represents a region of electron density and therefore functions as a <a class=\"internal mt-disabled\" title=\"Wikitexts\/UCD Chem 118A\/ChemWiki Module Topics for Chem 118B\/Acids and Bases; Electrophiles and Nucleophiles\" rel=\"broken\">nucleophile<\/a>.\u00a0How is it possible for a halogen to obtain positive charge to be an electrophile?<\/p>\n<div id=\"section_1\">\n<h3 class=\"editable\">Introduction<\/h3>\n<p>As halogen molecule, for example Br<sub>2<\/sub><sub>,<\/sub> approaches a double bond of the alkene, electrons in the double bond\u00a0 repel electrons in bromine molecule causing polarization of the halogen bond. This creates a dipolar moment in the halogen molecule bond. Heterolytic bond cleavage occurs and one of the halogens obtains positive charge and reacts as an electrophile. The reaction of the addition is not regioselective but stereoselective.Stereochemistry of this addition can be explained by the mechanism of the reaction.In the first step electrophilic halogen with a positive charge approaches\u00a0 the double carbon bond and 2 p orbitals of the halogen, bond with two carbon atoms and create a cyclic ion\u00a0 with a halogen as the intermediate step. In the second step, halogen with the negative charge attacks any of the two carbons in the cyclic ion from the\u00a0 back side of the cycle as in the <a title=\"SN2 reactions\" href=\"https:\/\/chem.libretexts.org\/Core\/Physical_and_Theoretical_Chemistry\/Kinetics\/Rate_Laws\/Gas_Phase_Kinetics\/Bimolecular_SN2_Reactions\/SN2_reactions\" rel=\"internal\"><span class=\"internal\">S<sub>N<\/sub>2 reaction<\/span><\/a>. Therefore stereochemistry of the product is vicinial dihalides through <strong>anti<\/strong> addition.<\/p>\n<p>\\[\\ce{R_2C=CR_2\u00a0\u00a0 +\u00a0 X_2\u00a0\u00a0 \\rightarrow\u00a0 R_2CX-CR_2X} \\tag{8.2.1}\\]<\/p>\n<p>Halogens that are commonly used in this type of the reaction are: $$Br$$ and $$Cl$$. In thermodynamical terms $$I$$ is too slow for this reaction because of the size of its atom, and $$F$$ is too vigorous and explosive. Solvents that are used for this type of electrophilic halogenation are inert (e.g., CCl<sub>4<\/sub>) can be used in this reaction.<\/p>\n<p>Because halogen with negative charge can attack any\u00a0 carbon from the opposite side of the cycle it creates a mixture of steric products.Optically inactive starting material produce optically inactive achiral products (<a class=\"internal\" title=\"Organic Chemistry\/Chirality\/Meso Compounds\" href=\"https:\/\/chem.libretexts.org\/Core\/Organic_Chemistry\/Chirality\/Meso_Compounds\" rel=\"internal\">meso<\/a>) or a <a title=\"Resolution of Racemates\" href=\"https:\/\/chem.libretexts.org\/Core\/Organic_Chemistry\/Chirality\/Stereoisomers\/Chirality_and_Symmetry\/Enantiomorphism\/Resolution_of_Racemates\" rel=\"internal\"><span class=\"internal\">racemic mixture<\/span><\/a>.<\/p>\n<\/div>\n<div id=\"section_2\">\n<h3 class=\"editable\">Electrophilic addition mechanism consists of two steps.<\/h3>\n<p>Before constructing the mechanism let us summarize conditions for this reaction. We will use Br<sub>2<\/sub> in our example for halogenation of ethylene.<\/p>\n<table style=\"border-spacing: 1px;width: 281px\" cellpadding=\"1\">\n<tbody>\n<tr>\n<td><strong>Nucleophile<\/strong><\/td>\n<td><strong>Double bond in alkene<\/strong><\/td>\n<\/tr>\n<tr>\n<td>Electrophile<\/td>\n<td>Br<sub>2<\/sub><sub>,<\/sub>\u00a0Cl<sub>2<\/sub><\/td>\n<\/tr>\n<tr>\n<td><strong>Regio<\/strong>chemistry<\/td>\n<td>not relevant<\/td>\n<\/tr>\n<tr>\n<td><strong>Stereo<\/strong>chemistry<\/td>\n<td><strong>\u00a0\u00a0ANTI<\/strong><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>Step 1: In the first step of the addition the Br-Br bond polarizes, heterolytic cleavage occurs and Br with the positive charge forms a intermediate cycle with the double bond.<\/p>\n<p><img decoding=\"async\" class=\"internal default aligncenter\" src=\"https:\/\/chem.libretexts.org\/@api\/deki\/files\/2030\/Mechanism1.bmp?revision=1&amp;size=bestfit&amp;width=360&amp;height=150#fixme\" alt=\"Mechanism1.bmp\" width=\"360px\" height=\"150px\" \/><\/p>\n<p>Step 2: In the second step, bromide anion attacks any carbon of the bridged bromonium ion from the back side of the cycle. Cycle opens up and two halogens are in the position <strong>anti<\/strong>.<\/p>\n<p><img decoding=\"async\" class=\"internal default aligncenter\" src=\"https:\/\/chem.libretexts.org\/@api\/deki\/files\/2028\/Mechanism_2_a.bmp?revision=1&amp;size=bestfit&amp;width=337&amp;height=128#fixme\" alt=\"Mechanism 2 a.bmp\" width=\"337px\" height=\"128px\" \/><\/p>\n<\/div>\n<div id=\"section_3\">\n<h3 class=\"editable\">Summary<\/h3>\n<p>Hallogens can act as electrophiles due to polarizability of their covalent bond.Addition of halogens is stereospecific and produces vicinial dihalides with anti addition.Cis starting material will give mixture of enantiomers and trans produces a meso compound.<\/p>\n<\/div>\n<div id=\"section_4\">\n<h3 class=\"editable\">References<\/h3>\n<ol>\n<li>Vollhard,K.Peter C., and Neil E.Schore.<u>Organic Chemistry:Structure and Function.<\/u>New Yourk: W.H.Freeman and Company 2007<\/li>\n<li><u>Chemestry-A Europian Journal<\/u> 9 (2003) :1036-1044<\/li>\n<\/ol>\n<\/div>\n<div id=\"section_5\">\n<div class=\"textbox examples\">\n<h3>Examples<\/h3>\n<h3 class=\"editable\">Problems<\/h3>\n<p>1.What is the mechanism of adding Cl<sub>2<\/sub> to the cyclohexene?<\/p>\n<p><img decoding=\"async\" class=\"internal default aligncenter\" src=\"https:\/\/chem.libretexts.org\/@api\/deki\/files\/2022\/Chem2.bmp?revision=1&amp;size=bestfit&amp;width=268&amp;height=74#fixme\" alt=\"Chem2.bmp\" width=\"268px\" height=\"74px\" \/><\/p>\n<p>2.A reaction of Br<sub>2<\/sub> molecule in an inert solvent with alkene follows?<\/p>\n<p>a) syn addition<\/p>\n<p>b) anti addition<\/p>\n<p>c) Morkovnikov rule<\/p>\n<p>3)<img decoding=\"async\" class=\"internal default\" src=\"https:\/\/chem.libretexts.org\/@api\/deki\/files\/2023\/Chem5_Q.bmp?revision=1&amp;size=bestfit&amp;width=221&amp;height=45#fixme\" alt=\"Chem5 Q.bmp\" width=\"221px\" height=\"45px\" \/><\/p>\n<p>4)<img decoding=\"async\" class=\"internal default\" src=\"https:\/\/chem.libretexts.org\/@api\/deki\/files\/2020\/Chem_5_Q.bmp?revision=1&amp;size=bestfit&amp;width=167&amp;height=48#fixme\" alt=\"Chem 5 Q.bmp\" width=\"167px\" height=\"48px\" \/><\/p>\n<h3>ANSWERS<\/h3>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q495877\">Show Answer<\/span><\/p>\n<div id=\"q495877\" class=\"hidden-answer\" style=\"display: none\">\n<p>1.<\/p>\n<p><img decoding=\"async\" class=\"internal aligncenter\" src=\"https:\/\/chem.libretexts.org\/@api\/deki\/files\/2027\/Choloro__problem_2.bmp?revision=1&amp;size=bestfit&amp;width=697&amp;height=181#fixme\" alt=\"Choloro problem 2.bmp\" width=\"697px\" height=\"181px\" \/><\/p>\n<p>2.\u00a0b<\/p>\n<p>3.<img decoding=\"async\" class=\"internal default aligncenter\" src=\"https:\/\/chem.libretexts.org\/@api\/deki\/files\/2021\/Chem_exampl_4.bmp?revision=1&amp;size=bestfit&amp;width=349&amp;height=92#fixme\" alt=\"Chem exampl 4.bmp\" width=\"349px\" height=\"92px\" \/>enantiomer<\/p>\n<p>4.<img decoding=\"async\" class=\"internal default aligncenter\" src=\"https:\/\/chem.libretexts.org\/@api\/deki\/files\/2024\/Chemestry_problem_4.bmp?revision=1&amp;size=bestfit&amp;width=278&amp;height=54#fixme\" alt=\"Chemestry problem 4.bmp\" width=\"278px\" height=\"54px\" \/><\/div>\n<\/div>\n<\/div>\n<\/div>\n<div id=\"section_6\">\n<div class=\"textbox exercises\">\n<h3 class=\"editable\">Exercises<\/h3>\n<div id=\"s61713\">\n<div id=\"section_8\">\n<h3 id=\"Questions-61713\">Questions<\/h3>\n<p><strong>1.<\/strong><\/p>\n<p>Predict the product of the product of 1,2-dimethylcyclopentene reacting with Br<sub>2<\/sub> with proper stereochemistry.<\/p>\n<p><strong>2.<\/strong><\/p>\n<p>Predict the products for 1,2-dimethylcyclpentene reacting with HCl, give the proper stereochemistry. What is the relationship between the two products?<\/p>\n<\/div>\n<div id=\"section_9\">\n<h3 id=\"Solutions-61713\">Solutions<\/h3>\n<p><strong><\/p>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q991501\">Show Answer<\/span><\/p>\n<div id=\"q991501\" class=\"hidden-answer\" style=\"display: none\">1.<\/strong><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"internal default aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1518\/2017\/10\/05141559\/8.2.png\" alt=\"\" width=\"146\" height=\"160\" \/><\/p>\n<p><strong>2.<\/strong><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"internal default aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1518\/2017\/10\/05141601\/8.22.png\" alt=\"\" width=\"343\" height=\"145\" \/><\/p>\n<p>These compounds are enantiomers<strong><\/div>\n<\/div>\n<p><\/strong><\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<div id=\"section_7\">\n<h3 class=\"editable\">Contributors<\/h3>\n<ul>\n<li><a class=\"external\" title=\"http:\/\/science.athabascau.ca\/staff-pages\/dietmark\" href=\"http:\/\/science.athabascau.ca\/staff-pages\/dietmark\" target=\"_blank\" rel=\"external nofollow noopener\">Dr. Dietmar Kennepohl<\/a> FCIC (Professor of Chemistry, <a class=\"external\" title=\"http:\/\/www.athabascau.ca\/\" href=\"http:\/\/www.athabascau.ca\/\" target=\"_blank\" rel=\"external nofollow noopener\">Athabasca University<\/a>)<\/li>\n<li>Prof. Steven Farmer (<a class=\"external\" title=\"http:\/\/www.sonoma.edu\" href=\"http:\/\/www.sonoma.edu\" target=\"_blank\" rel=\"external nofollow noopener\">Sonoma State University<\/a>)<\/li>\n<li>Jim Clark (<a class=\"external\" title=\"http:\/\/www.chemguide.co.uk\" href=\"http:\/\/www.chemguide.co.uk\" target=\"_blank\" rel=\"external nofollow noopener\">Chemguide.co.uk<\/a>)<\/li>\n<\/ul>\n<\/div>\n<\/div>\n","protected":false},"author":44985,"menu_order":1,"template":"","meta":{"_candela_citation":"[]","CANDELA_OUTCOMES_GUID":"","pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-1059","chapter","type-chapter","status-publish","hentry"],"part":24,"_links":{"self":[{"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-organicchemistry\/wp-json\/pressbooks\/v2\/chapters\/1059","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-organicchemistry\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-organicchemistry\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-organicchemistry\/wp-json\/wp\/v2\/users\/44985"}],"version-history":[{"count":6,"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-organicchemistry\/wp-json\/pressbooks\/v2\/chapters\/1059\/revisions"}],"predecessor-version":[{"id":2295,"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-organicchemistry\/wp-json\/pressbooks\/v2\/chapters\/1059\/revisions\/2295"}],"part":[{"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-organicchemistry\/wp-json\/pressbooks\/v2\/parts\/24"}],"metadata":[{"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-organicchemistry\/wp-json\/pressbooks\/v2\/chapters\/1059\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-organicchemistry\/wp-json\/wp\/v2\/media?parent=1059"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-organicchemistry\/wp-json\/pressbooks\/v2\/chapter-type?post=1059"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-organicchemistry\/wp-json\/wp\/v2\/contributor?post=1059"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-organicchemistry\/wp-json\/wp\/v2\/license?post=1059"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}