{"id":947,"date":"2018-11-28T16:08:43","date_gmt":"2018-11-28T16:08:43","guid":{"rendered":"https:\/\/courses.lumenlearning.com\/suny-potsdam-organicchemistry2\/?post_type=chapter&#038;p=947"},"modified":"2019-01-08T14:56:01","modified_gmt":"2019-01-08T14:56:01","slug":"19-1-definition-of-oxidation-state-for-carbon","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/suny-potsdam-organicchemistry2\/chapter\/19-1-definition-of-oxidation-state-for-carbon\/","title":{"raw":"19.1. Definition of oxidation state for carbon","rendered":"19.1. Definition of oxidation state for carbon"},"content":{"raw":"<header class=\"elm-header\">\r\n<div class=\"elm-header-custom\">\r\n<h2>Definition of oxidation state for carbon<\/h2>\r\n<p class=\"mt-container-secondary\">As we begin to look at organic redox reactions, it is useful to consider how we define the oxidation state for carbon.\u00a0 Most of the redox reactions in this chapter involve a change in the oxidation state of the carbon bearing the functional group.\u00a0 To calculate the oxidation state for carbon, use the following guidelines:<\/p>\r\n\r\n<\/div>\r\n<\/header><article id=\"elm-main-content\" class=\"elm-content-container\"><section class=\"mt-content-container\">\r\n<ol>\r\n \t<li>In a C-H bond, the H is treated as if it has an oxidation state of +1. This means that every C-H bond will <strong>decrease<\/strong> the oxidation state of carbon by 1.<\/li>\r\n \t<li>For carbon bonded to a more electronegative non-metal X, such as nitrogen, oxygen, sulfur or the halogens, each C-X bond will <strong>increase<\/strong> the oxidation state of the carbon by 1. (Certain non-metals are less electronegative than carbon, such as phosphorus, silicon or boron, but bonds from carbon to these elements are much less common.)<\/li>\r\n \t<li>For carbon bonded to another carbon, the oxidation state is unaffected.\u00a0 So a carbon attached to 4 carbons has an oxidation state of zero.<\/li>\r\n<\/ol>\r\nSo unlike metals, which are almost always in a positive oxidation state, the oxidation state of carbon can vary widely, from -4 (in CH4) to +4 (such as in CO2). Here are some examples.\r\n\r\n<a class=\"external\" href=\"http:\/\/masterorganicchemistry.com\/wp-content\/uploads\/2011\/07\/oxstate-12.jpg\" target=\"_blank\" rel=\"external nofollow noopener\"><img class=\"aligncenter size-full wp-image-2510\" title=\"oxstate-1\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/3773\/2018\/11\/28160559\/oxstate-12.jpg\" alt=\"\" width=\"518\" height=\"1262\" \/><\/a>\r\n\r\n(Don\u2019t forget that this is called a \u201cformalism\u201d for a reason. The charge on the carbon is not\u00a0<strong>really <\/strong>+4 or \u20134. But the oxidation state formalism helps us keep track of where the electrons are going, which will come in handy very soon).\r\n\r\nWith an understanding of how to calculate oxidation states on carbon, we\u2019re ready for the next step: understanding\u00a0<strong>changes<\/strong>\u00a0in the oxidation state at carbon, through reactions known as<strong> oxidations\u00a0<\/strong>(where the oxidation state is increased), and\u00a0<strong>reductions<\/strong>\u00a0(where the oxidation state is reduced). More on that next time.\r\n<div id=\"section_1\" class=\"mt-section\">\r\n<h2 class=\"editable\">Further Reading<\/h2>\r\n<a class=\"external\" title=\"http:\/\/www.masterorganicchemistry.com\/2011\/08\/08\/oxidation-ladders\/\" href=\"http:\/\/www.masterorganicchemistry.com\/2011\/08\/08\/oxidation-ladders\/\" target=\"_blank\" rel=\"external nofollow noopener\">The oxidation ladder<\/a>\r\n<div id=\"section_2\" class=\"mt-section\">\r\n<h4 class=\"editable\">References<\/h4>\r\n<ol>\r\n \t<li><a class=\"external\" href=\"http:\/\/www.masterorganicchemistry.com\/2011\/07\/25\/calculating-the-oxidation-state-of-a-carbon\/\" target=\"_blank\" rel=\"external nofollow noopener\">http:\/\/www.masterorganicchemistry.co...e-of-a-carbon\/<\/a><\/li>\r\n<\/ol>\r\n<\/div>\r\n<div id=\"section_3\" class=\"mt-section\">\r\n<h4 class=\"editable\">Contributors<\/h4>\r\n<ul>\r\n \t<li><strong>James Ashenhurst<\/strong> (<a class=\"external\" title=\"http:\/\/www.masterorganicchemistry.com\/\" href=\"http:\/\/www.masterorganicchemistry.com\/\" target=\"_blank\" rel=\"external nofollow noopener\">MasterOrganicChemistry.com<\/a>)<\/li>\r\n<\/ul>\r\n<header>\r\n<h2 id=\"title\">Oxidation and reduction of organic compounds - an overview<\/h2>\r\n<dl class=\"mt-last-updated-container\"><\/dl>\r\n<\/header>You are undoubtedly already familiar with the general idea of oxidation and reduction: you learned in general chemistry that when a compound or atom is oxidized it loses electrons, and when it is reduced it gains electrons.\u00a0 You also know that oxidation and reduction reactions occur in pairs: if one species is oxidized, another must be reduced at the same time -\u00a0 thus the term 'redox reaction'.Most of the redox reactions you have seen previously in general chemistry probably involved the flow of electrons from one metal to another, such as the reaction between copper ion in solution and metallic zinc:\r\n\r\n<section class=\"mt-content-container\">\r\n<p style=\"text-align: center\">\\[Cu^{+2}_{(aq)}\u00a0 + Zn_{(s)} \\rightarrow Cu_{(s)} + Zn^{+2}_{(aq)} \\tag{16.1.1}\\]<\/p>\r\nIn organic chemistry, redox reactions look a little different. Electrons in an organic redox reaction often are transferred in the form of a hydride ion - a proton and two electrons. Because they occur in conjunction with the transfer of a proton, these are commonly referred to as <strong>hydrogenation<\/strong> and <strong>dehydrogenation<\/strong> reactions: a hydride plus a proton adds up to a hydrogen (H<sub>2<\/sub>) molecule.\u00a0 Be careful - do not confuse the terms hyd<strong><u>rogen<\/u><\/strong>ation and dehy<strong><u>drogen<\/u><\/strong>ation with hydration and dehydration - the latter refer to the gain and loss of a <em>water<\/em> molecule (and are <em>not<\/em> redox reactions), while the former refer to the gain and loss of a <em>hydrogen<\/em> molecule.\r\n\r\nWhen a carbon atom in an organic compound loses a bond to hydrogen and gains a new bond to a heteroatom (or to another carbon),\u00a0 we say the compound has been dehydrogenated, or oxidized. A very common biochemical example is the oxidation of an alcohol to a ketone or aldehyde:\r\n\r\n<img class=\"internal default aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/3773\/2018\/11\/28160727\/image005.png\" alt=\"image006.png\" width=\"588\" height=\"148\" \/>\r\n\r\nWhen a carbon atom loses a bond to hydrogen and gains a bond to a heteroatom (or to another carbon atom), it is considered to be an oxidative process because hydrogen, of all the elements, is the least electronegative.\u00a0 Thus, in the process of dehydrogenation the carbon atom undergoes an overall loss of electron density - and loss of electrons is oxidation.\r\n\r\nConversely, when a carbon atom in an organic compound gains a bond to hydrogen and loses a bond to a heteroatom (or to another carbon atom), we say that the compound has been hydrogenated, or reduced.\u00a0 The hydrogenation of a ketone to an alcohol, for example, is overall the reverse of the alcohol dehydrogenation\u00a0 shown above.\u00a0 Illustrated below is another common possibility, the hydrogenation (reduction) of an alkene to an alkane.\r\n\r\n<img class=\"internal default aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/3773\/2018\/11\/28160730\/image007.png\" alt=\"image008.png\" width=\"533\" height=\"103\" \/>\r\n\r\nHydrogenation results in <em>higher<\/em> electron density on a carbon atom(s), and thus we consider process to be one of reduction of the organic molecule.\r\n\r\nNotice that neither hydrogenation nor dehydrogenation involves the gain or loss of an oxygen <em>atom<\/em>.\u00a0 Reactions which <em>do<\/em> involve gain or loss of one or more oxygen atoms are usually referred to as 'oxygenase' and 'reductase' reactions.\r\n\r\nFor the most part, when talking about redox reactions in organic chemistry we are dealing with a small set of very recognizable functional group transformations.\u00a0 It is therefore very worthwhile to become familiar with the idea of 'oxidation states' as applied to organic functional groups.\u00a0 By comparing the relative number of bonds to hydrogen atoms, we can order the familiar functional groups according to oxidation state.\u00a0 We'll take a series of single carbon compounds as an example.\u00a0 Methane, with four carbon-hydrogen bonds, is highly reduced.\u00a0 Next in the series is methanol (one less carbon-hydrogen bond, one more carbon-oxygen bond), followed by formaldehyde, formate, and finally carbon dioxide at the highly oxidized end of the group.\r\n\r\n<img class=\"internal default aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/3773\/2018\/11\/28160733\/image009.png\" alt=\"image010.png\" width=\"518\" height=\"110\" \/>\r\n\r\nThis pattern holds true for the relevant functional groups on organic molecules with two or more carbon atoms:\r\n\r\n<img class=\"internal default\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/3773\/2018\/11\/28160736\/image011.png\" alt=\"image012.png\" width=\"635\" height=\"111\" \/>\r\n\r\nAlkanes are highly reduced, while alcohols - as well as alkenes, ethers, amines, sulfides, and phosphate esters - are one step up on the oxidation scale, followed by aldehydes\/ketones\/imines and epoxides, and finally by carboxylic acid derivatives (carbon dioxide, at the top of the oxidation list, is specific to the single carbon series).\r\n\r\nNotice that in the series of two-carbon compounds above, ethanol and ethene are considered to be in the same oxidation state.\u00a0 You know already that alcohols and alkenes are interconverted by way of addition or elimination of water (for example in <a href=\"https:\/\/courses.lumenlearning.com\/suny-potsdam-organicchemistry2\/chapter\/10-4-simple-addition-to-alkenes\/\">section 10.4.<\/a>). When an alcohol is dehydrated to form an alkene, one of the two carbons loses a C-H bond and gains a C-C bond, and thus is oxidized.\u00a0 However, the other carbon loses a C-O bond and gains a C-C bond, and thus is considered to be reduced.\u00a0 Overall, therefore, there is no change to the oxidation state of the carbons considered together.\r\n\r\nYou should learn to recognize when a reaction involves a change in oxidation state of the carbons in an organic reactant. Looking at the following transformation, for example, you should be able to quickly recognize that it is an oxidation: an alcohol functional group is converted to a ketone, which is one step up on the oxidation ladder.\r\n\r\n<img class=\"internal default aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/3773\/2018\/11\/28160739\/image013.png\" alt=\"image014.png\" width=\"337\" height=\"138\" \/>\r\n\r\nLikewise, this next reaction involves the transformation of a carboxylic acid derivative (a thioester) first to an aldehyde, then to an alcohol: this is a <em>double<\/em> reduction, as the substrate loses two bonds to heteroatoms and gains two bonds to hydrogens.\r\n\r\n<img class=\"internal default aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/3773\/2018\/11\/28160742\/image015.png\" alt=\"image016.png\" width=\"700\" height=\"95\" \/>\r\n\r\nAn acyl transfer reaction (for example the conversion of an acyl phosphate to an amide) is <em>not<\/em> considered to be a redox reaction - the oxidation state of the organic molecule is does not change as substrate is converted to product, because a bond to one heteroatom (oxygen) has simply been traded for a bond to another heteroatom (nitrogen).\r\n\r\n<img class=\"internal default aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/3773\/2018\/11\/28160745\/image017.png\" alt=\"image018.png\" width=\"314\" height=\"120\" \/>\r\n\r\nIt is important to be able to recognize when an organic molecule is being oxidized or reduced, because this information tells you to look for the participation of a corresponding redox agent that is being reduced or oxidized- remember, oxidation and reduction always occur in tandem! We will soon learn in detail about the most important biochemical and laboratory redox agents.\r\n<div id=\"section_1\" class=\"mt-section\">\r\n<ul>\r\n \t<li><a title=\"http:\/\/chemwiki.ucdavis.edu\/Organic_Chemistry\/Organic_Chemistry_With_a_Biological_Emphasis\" href=\"https:\/\/chem.libretexts.org\/Textbook_Maps\/Organic_Chemistry\/Book%3A_Organic_Chemistry_with_a_Biological_Emphasis_(Soderberg)\" rel=\"internal\"><strong>Organic Chemistry With a Biological Emphasis <\/strong><\/a>by\u00a0<a class=\"external\" title=\"http:\/\/facultypages.morris.umn.edu\/~soderbt\/\" href=\"http:\/\/facultypages.morris.umn.edu\/%7Esoderbt\/\" target=\"_blank\" rel=\"external nofollow noopener\">Tim Soderberg<\/a>\u00a0(University of Minnesota, Morris)<\/li>\r\n<\/ul>\r\nhttps:\/\/youtu.be\/bJMUKNbAsTY\r\n\r\n<img class=\"alignleft wp-image-2956 size-thumbnail\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/3773\/2018\/11\/08134219\/frame-30-150x150.png\" alt=\"\" width=\"150\" height=\"150\" \/>\r\n\r\n<\/div>\r\n<\/section><\/div>\r\n<\/div>\r\n<\/section><\/article>","rendered":"<header class=\"elm-header\">\n<div class=\"elm-header-custom\">\n<h2>Definition of oxidation state for carbon<\/h2>\n<p class=\"mt-container-secondary\">As we begin to look at organic redox reactions, it is useful to consider how we define the oxidation state for carbon.\u00a0 Most of the redox reactions in this chapter involve a change in the oxidation state of the carbon bearing the functional group.\u00a0 To calculate the oxidation state for carbon, use the following guidelines:<\/p>\n<\/div>\n<\/header>\n<article id=\"elm-main-content\" class=\"elm-content-container\">\n<section class=\"mt-content-container\">\n<ol>\n<li>In a C-H bond, the H is treated as if it has an oxidation state of +1. This means that every C-H bond will <strong>decrease<\/strong> the oxidation state of carbon by 1.<\/li>\n<li>For carbon bonded to a more electronegative non-metal X, such as nitrogen, oxygen, sulfur or the halogens, each C-X bond will <strong>increase<\/strong> the oxidation state of the carbon by 1. (Certain non-metals are less electronegative than carbon, such as phosphorus, silicon or boron, but bonds from carbon to these elements are much less common.)<\/li>\n<li>For carbon bonded to another carbon, the oxidation state is unaffected.\u00a0 So a carbon attached to 4 carbons has an oxidation state of zero.<\/li>\n<\/ol>\n<p>So unlike metals, which are almost always in a positive oxidation state, the oxidation state of carbon can vary widely, from -4 (in CH4) to +4 (such as in CO2). Here are some examples.<\/p>\n<p><a class=\"external\" href=\"http:\/\/masterorganicchemistry.com\/wp-content\/uploads\/2011\/07\/oxstate-12.jpg\" target=\"_blank\" rel=\"external nofollow noopener\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-2510\" title=\"oxstate-1\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/3773\/2018\/11\/28160559\/oxstate-12.jpg\" alt=\"\" width=\"518\" height=\"1262\" \/><\/a><\/p>\n<p>(Don\u2019t forget that this is called a \u201cformalism\u201d for a reason. The charge on the carbon is not\u00a0<strong>really <\/strong>+4 or \u20134. But the oxidation state formalism helps us keep track of where the electrons are going, which will come in handy very soon).<\/p>\n<p>With an understanding of how to calculate oxidation states on carbon, we\u2019re ready for the next step: understanding\u00a0<strong>changes<\/strong>\u00a0in the oxidation state at carbon, through reactions known as<strong> oxidations\u00a0<\/strong>(where the oxidation state is increased), and\u00a0<strong>reductions<\/strong>\u00a0(where the oxidation state is reduced). More on that next time.<\/p>\n<div id=\"section_1\" class=\"mt-section\">\n<h2 class=\"editable\">Further Reading<\/h2>\n<p><a class=\"external\" title=\"http:\/\/www.masterorganicchemistry.com\/2011\/08\/08\/oxidation-ladders\/\" href=\"http:\/\/www.masterorganicchemistry.com\/2011\/08\/08\/oxidation-ladders\/\" target=\"_blank\" rel=\"external nofollow noopener\">The oxidation ladder<\/a><\/p>\n<div id=\"section_2\" class=\"mt-section\">\n<h4 class=\"editable\">References<\/h4>\n<ol>\n<li><a class=\"external\" href=\"http:\/\/www.masterorganicchemistry.com\/2011\/07\/25\/calculating-the-oxidation-state-of-a-carbon\/\" target=\"_blank\" rel=\"external nofollow noopener\">http:\/\/www.masterorganicchemistry.co&#8230;e-of-a-carbon\/<\/a><\/li>\n<\/ol>\n<\/div>\n<div id=\"section_3\" class=\"mt-section\">\n<h4 class=\"editable\">Contributors<\/h4>\n<ul>\n<li><strong>James Ashenhurst<\/strong> (<a class=\"external\" title=\"http:\/\/www.masterorganicchemistry.com\/\" href=\"http:\/\/www.masterorganicchemistry.com\/\" target=\"_blank\" rel=\"external nofollow noopener\">MasterOrganicChemistry.com<\/a>)<\/li>\n<\/ul>\n<header>\n<h2 id=\"title\">Oxidation and reduction of organic compounds &#8211; an overview<\/h2>\n<dl class=\"mt-last-updated-container\"><\/dl>\n<\/header>\n<p>You are undoubtedly already familiar with the general idea of oxidation and reduction: you learned in general chemistry that when a compound or atom is oxidized it loses electrons, and when it is reduced it gains electrons.\u00a0 You also know that oxidation and reduction reactions occur in pairs: if one species is oxidized, another must be reduced at the same time &#8211;\u00a0 thus the term &#8216;redox reaction&#8217;.Most of the redox reactions you have seen previously in general chemistry probably involved the flow of electrons from one metal to another, such as the reaction between copper ion in solution and metallic zinc:<\/p>\n<section class=\"mt-content-container\">\n<p style=\"text-align: center\">\\[Cu^{+2}_{(aq)}\u00a0 + Zn_{(s)} \\rightarrow Cu_{(s)} + Zn^{+2}_{(aq)} \\tag{16.1.1}\\]<\/p>\n<p>In organic chemistry, redox reactions look a little different. Electrons in an organic redox reaction often are transferred in the form of a hydride ion &#8211; a proton and two electrons. Because they occur in conjunction with the transfer of a proton, these are commonly referred to as <strong>hydrogenation<\/strong> and <strong>dehydrogenation<\/strong> reactions: a hydride plus a proton adds up to a hydrogen (H<sub>2<\/sub>) molecule.\u00a0 Be careful &#8211; do not confuse the terms hyd<strong><u>rogen<\/u><\/strong>ation and dehy<strong><u>drogen<\/u><\/strong>ation with hydration and dehydration &#8211; the latter refer to the gain and loss of a <em>water<\/em> molecule (and are <em>not<\/em> redox reactions), while the former refer to the gain and loss of a <em>hydrogen<\/em> molecule.<\/p>\n<p>When a carbon atom in an organic compound loses a bond to hydrogen and gains a new bond to a heteroatom (or to another carbon),\u00a0 we say the compound has been dehydrogenated, or oxidized. A very common biochemical example is the oxidation of an alcohol to a ketone or aldehyde:<\/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\/3773\/2018\/11\/28160727\/image005.png\" alt=\"image006.png\" width=\"588\" height=\"148\" \/><\/p>\n<p>When a carbon atom loses a bond to hydrogen and gains a bond to a heteroatom (or to another carbon atom), it is considered to be an oxidative process because hydrogen, of all the elements, is the least electronegative.\u00a0 Thus, in the process of dehydrogenation the carbon atom undergoes an overall loss of electron density &#8211; and loss of electrons is oxidation.<\/p>\n<p>Conversely, when a carbon atom in an organic compound gains a bond to hydrogen and loses a bond to a heteroatom (or to another carbon atom), we say that the compound has been hydrogenated, or reduced.\u00a0 The hydrogenation of a ketone to an alcohol, for example, is overall the reverse of the alcohol dehydrogenation\u00a0 shown above.\u00a0 Illustrated below is another common possibility, the hydrogenation (reduction) of an alkene to an alkane.<\/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\/3773\/2018\/11\/28160730\/image007.png\" alt=\"image008.png\" width=\"533\" height=\"103\" \/><\/p>\n<p>Hydrogenation results in <em>higher<\/em> electron density on a carbon atom(s), and thus we consider process to be one of reduction of the organic molecule.<\/p>\n<p>Notice that neither hydrogenation nor dehydrogenation involves the gain or loss of an oxygen <em>atom<\/em>.\u00a0 Reactions which <em>do<\/em> involve gain or loss of one or more oxygen atoms are usually referred to as &#8216;oxygenase&#8217; and &#8216;reductase&#8217; reactions.<\/p>\n<p>For the most part, when talking about redox reactions in organic chemistry we are dealing with a small set of very recognizable functional group transformations.\u00a0 It is therefore very worthwhile to become familiar with the idea of &#8216;oxidation states&#8217; as applied to organic functional groups.\u00a0 By comparing the relative number of bonds to hydrogen atoms, we can order the familiar functional groups according to oxidation state.\u00a0 We&#8217;ll take a series of single carbon compounds as an example.\u00a0 Methane, with four carbon-hydrogen bonds, is highly reduced.\u00a0 Next in the series is methanol (one less carbon-hydrogen bond, one more carbon-oxygen bond), followed by formaldehyde, formate, and finally carbon dioxide at the highly oxidized end of the group.<\/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\/3773\/2018\/11\/28160733\/image009.png\" alt=\"image010.png\" width=\"518\" height=\"110\" \/><\/p>\n<p>This pattern holds true for the relevant functional groups on organic molecules with two or more carbon atoms:<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"internal default\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/3773\/2018\/11\/28160736\/image011.png\" alt=\"image012.png\" width=\"635\" height=\"111\" \/><\/p>\n<p>Alkanes are highly reduced, while alcohols &#8211; as well as alkenes, ethers, amines, sulfides, and phosphate esters &#8211; are one step up on the oxidation scale, followed by aldehydes\/ketones\/imines and epoxides, and finally by carboxylic acid derivatives (carbon dioxide, at the top of the oxidation list, is specific to the single carbon series).<\/p>\n<p>Notice that in the series of two-carbon compounds above, ethanol and ethene are considered to be in the same oxidation state.\u00a0 You know already that alcohols and alkenes are interconverted by way of addition or elimination of water (for example in <a href=\"https:\/\/courses.lumenlearning.com\/suny-potsdam-organicchemistry2\/chapter\/10-4-simple-addition-to-alkenes\/\">section 10.4.<\/a>). When an alcohol is dehydrated to form an alkene, one of the two carbons loses a C-H bond and gains a C-C bond, and thus is oxidized.\u00a0 However, the other carbon loses a C-O bond and gains a C-C bond, and thus is considered to be reduced.\u00a0 Overall, therefore, there is no change to the oxidation state of the carbons considered together.<\/p>\n<p>You should learn to recognize when a reaction involves a change in oxidation state of the carbons in an organic reactant. Looking at the following transformation, for example, you should be able to quickly recognize that it is an oxidation: an alcohol functional group is converted to a ketone, which is one step up on the oxidation ladder.<\/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\/3773\/2018\/11\/28160739\/image013.png\" alt=\"image014.png\" width=\"337\" height=\"138\" \/><\/p>\n<p>Likewise, this next reaction involves the transformation of a carboxylic acid derivative (a thioester) first to an aldehyde, then to an alcohol: this is a <em>double<\/em> reduction, as the substrate loses two bonds to heteroatoms and gains two bonds to hydrogens.<\/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\/3773\/2018\/11\/28160742\/image015.png\" alt=\"image016.png\" width=\"700\" height=\"95\" \/><\/p>\n<p>An acyl transfer reaction (for example the conversion of an acyl phosphate to an amide) is <em>not<\/em> considered to be a redox reaction &#8211; the oxidation state of the organic molecule is does not change as substrate is converted to product, because a bond to one heteroatom (oxygen) has simply been traded for a bond to another heteroatom (nitrogen).<\/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\/3773\/2018\/11\/28160745\/image017.png\" alt=\"image018.png\" width=\"314\" height=\"120\" \/><\/p>\n<p>It is important to be able to recognize when an organic molecule is being oxidized or reduced, because this information tells you to look for the participation of a corresponding redox agent that is being reduced or oxidized- remember, oxidation and reduction always occur in tandem! We will soon learn in detail about the most important biochemical and laboratory redox agents.<\/p>\n<div id=\"section_1\" class=\"mt-section\">\n<ul>\n<li><a title=\"http:\/\/chemwiki.ucdavis.edu\/Organic_Chemistry\/Organic_Chemistry_With_a_Biological_Emphasis\" href=\"https:\/\/chem.libretexts.org\/Textbook_Maps\/Organic_Chemistry\/Book%3A_Organic_Chemistry_with_a_Biological_Emphasis_(Soderberg)\" rel=\"internal\"><strong>Organic Chemistry With a Biological Emphasis <\/strong><\/a>by\u00a0<a class=\"external\" title=\"http:\/\/facultypages.morris.umn.edu\/~soderbt\/\" href=\"http:\/\/facultypages.morris.umn.edu\/%7Esoderbt\/\" target=\"_blank\" rel=\"external nofollow noopener\">Tim Soderberg<\/a>\u00a0(University of Minnesota, Morris)<\/li>\n<\/ul>\n<p><iframe loading=\"lazy\" id=\"oembed-1\" title=\"Organic oxidation-reduction reactions | Organic chemistry | Khan Academy\" width=\"500\" height=\"281\" src=\"https:\/\/www.youtube.com\/embed\/bJMUKNbAsTY?feature=oembed&#38;rel=0\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignleft wp-image-2956 size-thumbnail\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/3773\/2018\/11\/08134219\/frame-30-150x150.png\" alt=\"\" width=\"150\" height=\"150\" \/><\/p>\n<\/div>\n<\/section>\n<\/div>\n<\/div>\n<\/section>\n<\/article>\n\n\t\t\t <section class=\"citations-section\" role=\"contentinfo\">\n\t\t\t <h3>Candela Citations<\/h3>\n\t\t\t\t\t <div>\n\t\t\t\t\t\t <div id=\"citation-list-947\">\n\t\t\t\t\t\t\t <div class=\"licensing\"><div class=\"license-attribution-dropdown-subheading\">CC licensed content, Shared previously<\/div><ul class=\"citation-list\"><li>Oxidation States of Organic Molecules. <strong>Authored by<\/strong>: James Ashenhurst. <strong>Located at<\/strong>: <a target=\"_blank\" href=\"https:\/\/www.masterorganicchemistry.com\/\">https:\/\/www.masterorganicchemistry.com\/<\/a>. <strong>License<\/strong>: <em><a target=\"_blank\" rel=\"license\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\">CC BY-NC-SA: Attribution-NonCommercial-ShareAlike<\/a><\/em><\/li><li>Organic Chemistry with a Biological Emphasis. <strong>Authored by<\/strong>: Tim Soderberg. <strong>Located at<\/strong>: <a target=\"_blank\" href=\"https:\/\/chem.libretexts.org\/Textbook_Maps\/Organic_Chemistry\/Book%3A_Organic_Chemistry_with_a_Biological_Emphasis_(Soderberg)\">https:\/\/chem.libretexts.org\/Textbook_Maps\/Organic_Chemistry\/Book%3A_Organic_Chemistry_with_a_Biological_Emphasis_(Soderberg)<\/a>. <strong>Project<\/strong>: Chemistry LibreTexts. <strong>License<\/strong>: <em><a target=\"_blank\" rel=\"license\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\">CC BY-NC-SA: Attribution-NonCommercial-ShareAlike<\/a><\/em><\/li><\/ul><\/div>\n\t\t\t\t\t\t <\/div>\n\t\t\t\t\t <\/div>\n\t\t\t <\/section>","protected":false},"author":53384,"menu_order":1,"template":"","meta":{"_candela_citation":"[{\"type\":\"cc\",\"description\":\"Oxidation States of Organic Molecules\",\"author\":\"James Ashenhurst\",\"organization\":\"\",\"url\":\"https:\/\/www.masterorganicchemistry.com\/\",\"project\":\"\",\"license\":\"cc-by-nc-sa\",\"license_terms\":\"\"},{\"type\":\"cc\",\"description\":\"Organic Chemistry with a Biological Emphasis\",\"author\":\"Tim Soderberg\",\"organization\":\"\",\"url\":\"https:\/\/chem.libretexts.org\/Textbook_Maps\/Organic_Chemistry\/Book%3A_Organic_Chemistry_with_a_Biological_Emphasis_(Soderberg)\",\"project\":\"Chemistry 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