{"id":560,"date":"2017-08-21T10:26:25","date_gmt":"2017-08-21T10:26:25","guid":{"rendered":"http:\/\/americanboard.org\/Subjects\/chemistry\/?page_id=560"},"modified":"2017-09-08T04:24:44","modified_gmt":"2017-09-08T04:24:44","slug":"naming-organic-molecules","status":"publish","type":"page","link":"https:\/\/americanboard.org\/Subjects\/chemistry\/naming-organic-molecules\/","title":{"rendered":"Naming Organic Molecules"},"content":{"rendered":"<div class=\"twelve columns\" style=\"margin-top: 10%;\">\n<div class=\"advance\">\n<p><a class=\"button button-primary\" href=\"http:\/\/americanboard.org\/Subjects\/chemistry\/introduction\">\u2b05 Previous Lesson<\/a>\u00a0<a class=\"button\" href=\"http:\/\/americanboard.org\/Subjects\/chemistry\/organic-chemistry\">Workshop Index<\/a>\u00a0<a class=\"button button-primary\" href=\"http:\/\/americanboard.org\/Subjects\/chemistry\/naming-organic-molecules-containing-oxygen\">Next Lesson \u27a1<\/a><\/p>\n<\/div>\n<p><!-- UPDATE NEXT\/PREVIOUS ABOVE --><\/p>\n<p><!-- CONTENT STARTS HERE --><\/p>\n<h1 id=\"title\">Naming Organic Molecules<\/h1>\n<h4>Objective<\/h4>\n<p>In this lesson we will examine how alkenes, alkynes, cycloalkanes and cycloalkenes are named.<\/p>\n<h4>Previously we covered&#8230;<\/h4>\n<ul>\n<li>Organic chemistry is the study of carbon containing molecules.<\/li>\n<li>There are multiple ways to represent the structure of an organic molecule.<\/li>\n<li>Saturated molecules contain only single carbon-carbon bonds while unsaturated molecules contain at least one multiple bond.<\/li>\n<li>Alkanes are saturated hydrocarbons<\/li>\n<li>The alkane naming system is a logical progressive one.<\/li>\n<\/ul>\n<section>\n<h3>Naming Alkenes<\/h3>\n<p><abbr title=\"Hydrocarbons that contain one or more double bonds\">Alkenes<\/abbr> are hydrocarbons that contain one or more double bonds. To name alkenes find the longest chain of carbon atoms that contains the double bonds. The stem of the name is the number of carbons in the chain ( \u201ceth,\u201d \u201cprop,\u201d \u201cbut,\u201d etc.) followed by \u201cene\u201d to indicate that the molecule contains a double bond. Next, number the carbons in the chain from both directions, left to right and right to left; choose the way that gives the lowest number(s) to the carbon(s) where the double bond starts.<\/p>\n<p><center><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/americanboard.org\/Subjects\/Images\/chemistry\/img\/OrganicChemistry\/NamingOrganicMolecules2.1-penteneb.gif\" alt=\"1-pentene\" width=\"162\" height=\"18\" \/><\/center><\/p>\n<p>This molecule would be <em>1-pentene<\/em>.<br \/>\nIt is five carbons with a double bond between the first and second carbon atoms (counting right to left).<\/p>\n<p>If there are multiple double bonds then the name details how many carbons in the chain, again numbering in both directions using the sum of the numbers of where the double bonds start to determine the direction in which to go. Include the Greek prefix \u201cdi,\u201d \u201ctri,\u201d \u201ctetra,\u201d etc to indicate the number of double bonds.<\/p>\n<p><center><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/americanboard.org\/Subjects\/Images\/chemistry\/img\/OrganicChemistry\/NamingOrganicMolecules2.2,3-hexadiene.gif\" alt=\"2,3-hexadiene\" width=\"199\" height=\"18\" \/><\/center><\/p>\n<p>The name of this molecule is <em>2,3-hexadiene<\/em>. The \u201chex\u201d comes from the fact that there are six carbons in the chain. The numbers show where the double bonds start. The numbers 2 and 3 would be used since 2 plus 3 equals 5 which is smaller than 3 plus 4 which equals 7. The \u201cdi\u201d in the middle of the name indicates that there are two double bonds. The \u201ca\u201d is inserted for pronunciation because of adding a consonant \u201cd\u201d in \u201cdi\u201d after the \u201cx\u201d in \u201chex.\u201d<\/p>\n<p>When there are branches in alkenes they are handled the same way as with alkanes except the numbering of the double bond(s) dictates the direction in which the carbons in the chain are numbered. The starting of the double bonds needs to be as low as possible and once the direction is determined it is used throughout the name.<\/p>\n<p><center><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/americanboard.org\/Subjects\/Images\/chemistry\/img\/OrganicChemistry\/NamingOrganicMolecules2.4,5-dimethyl-1,3-hexadiene.gif\" width=\"229\" height=\"59\" \/><\/center><\/p>\n<p>The name of this molecule is <em>3,4-dimethyl-1,3-hexadiene<\/em>. The 3 and 4 indicate the location of the one-carbon branches. The \u201cdi\u201d methyl indicates that there are two one-carbon branches. The 1 and 3 show the start of the double bonds. The \u201chex\u201d indicates that here are six carbon atoms in the longest chain. The ending of \u201c-ene\u201d indicates that there are double bonds. The \u201cdi\u201d in the middle indicates that there are \u201cdi\u201d double bonds.<\/p>\n<h3>Naming Alkynes<\/h3>\n<p>Naming alkynes is the same as naming alkenes except the ending \u201cyne\u201d is used instead of \u201cene.\u201d<\/p>\n<p><abbr title=\"Hydrocarbons that contain one or more double bonds\">Alkynes<\/abbr> are hydrocarbons that contain one or more triple bonds.<\/p>\n<p><center><img decoding=\"async\" src=\"http:\/\/americanboard.org\/Subjects\/Images\/chemistry\/img\/OrganicChemistry\/NamingOrganicMolecules3.2butyne.gif\" alt=\"2 butyne\" width=\"229\" \/><\/center><\/p>\n<p>The name <em>2-butyne <\/em>would indicate that the molecule has four carbons in a chain with a triple bond between carbons 2 and 3.<\/p>\n<p><center><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/americanboard.org\/Subjects\/Images\/chemistry\/img\/OrganicChemistry\/NamingOrganicMolecules3.1,4-octadiyne.gif\" alt=\"1,4-octadiyne\" width=\"404\" height=\"68\" \/><\/center><\/p>\n<p>The name <em>1,4-octadiyne<\/em> would indicate that the molecule has eight carbons due to the \u201coct.\u201d The \u201cdi\u201d indicates that there are two triple bonds. The 1 and 4 shows the location of the triple bonds. The \u201ca\u201d in the middle is to make the name easier to pronounce.<\/p>\n<h3>Naming Cycloalkanes<\/h3>\n<p><abbr title=\" Hydrocarbons whose carbon atoms are arranged in a ring or \u201ccyclic\u201d structure\">Cycloalkanes<\/abbr> are hydrocarbons whose carbon atoms are arranged in a ring or cyclic structure. In order to name cycloalkanes count the number of carbon atoms in the ring and add the prefix \u201ccyclo.\u201d<\/p>\n<p><center><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/americanboard.org\/Subjects\/Images\/chemistry\/img\/OrganicChemistry\/NamingOrganicMolecules5.Cyclopentane.png\" alt=\"cyclopentane\" width=\"104\" height=\"114\" \/><\/center><\/p>\n<p>The name of this molecule is <em>cyclopentane<\/em>. The \u201ccyclo\u201d shows that it has a ring structure. The \u201cpent\u201d indicates there are five carbons. The \u201cane\u201d ending indicates the carbon atoms are singly bonded together.<\/p>\n<p>When there are branches attached to a cyclic molecule, name the ring structure, add the name(s) of the branches, and then tell the location(s) of the branches. You can start the numbering with any carbon of the ring and go in either a clockwise or counterclockwise direction.<\/p>\n<p><center><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/americanboard.org\/Subjects\/Images\/chemistry\/img\/OrganicChemistry\/NamingOrganicMolecules4.methylcyclohexane.gif\" alt=\"methylcyclopentane\" width=\"150\" height=\"116\" \/><\/center><\/p>\n<p>The name of this molecule is <em>methylcyclopentane.<\/em> Note that no number is needed with this molecule as no matter where the methyl group is it could be considered to be on the number one carbon.<\/p>\n<p><center><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/americanboard.org\/Subjects\/Images\/chemistry\/img\/OrganicChemistry\/NamingOrganicMolecules4.1-ethyl-2-methylcyclohexane.gif\" alt=\"1-ethyl-2-methylcyclopentane\" width=\"170\" height=\"227\" \/><\/center><\/p>\n<p>The name of this molecule is <em>1-ethyl-2-methylcyclopentane<\/em>. There are 5 carbons in a ring with single bonds between them, therefore it is a cyclopentane. Since there are both an \u201cethyl\u201d branch and a \u201cmethyl\u201d branch they are listed in alphabetical order and numbered to give the lowest sum.<\/p>\n<h3>Naming Cycloalkenes<\/h3>\n<p><abbr title=\" Hydrocarbons whose carbon atoms are arranged in a ring or \u201ccyclic\u201d structure\">Cycloalkenes<\/abbr> are hydrocarbons with carbon atoms arranged in a ring or cyclic structure and which have one or more double bonds between the carbon atoms. In order to name cycloalkenes count the number of carbon atoms in the ring, add the prefix \u201ccyclo,\u201d and include the suffix \u201cene\u201d instead of \u201cane.\u201d The location of the double bond(s) establishes the numbering of the carbon atoms in the ring. They get the lowest numbers even if the branches get higher numbers. Again one can go either clockwise or counterclockwise to get the lowest numbers. Also, if there is more than one double bond one needs to insert the Greek prefixes such as \u201cdi,\u201d \u201ctri,\u201d \u201ctetra,\u201d etc. to indicate how many double bonds there are in addition to the numbers showing their location.<\/p>\n<p><center><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/americanboard.org\/Subjects\/Images\/chemistry\/img\/OrganicChemistry\/NamingOrganicMolecules5.5-methyl-1,3-cyclohexadiene.gif\" alt=\"5-methyl-1,3-cyclohexadiene\" width=\"177\" height=\"191\" \/><\/center><\/p>\n<p>The name of this molecule is <em>5-methyl-1,3-cyclohexadiene<\/em>. The cyclohexadiene indicates there are six carbons in a ring with two double bonds. One double bond is between the 1<sup>st<\/sup> and 2<sup>nd<\/sup> carbons and one is between the 3<sup>rd<\/sup> and 4<sup>th<\/sup>. Also, there is a one carbon branch (methyl) on the 5<sup>th<\/sup> carbon. Notice that in order to give the double bond the lowest possible numbering the branch received a higher number.<\/p>\n<section class=\"question\">\n<h4>Question<\/h4>\n<p>What is the name of this molecule?<\/p>\n<p><center><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/americanboard.org\/Subjects\/Images\/chemistry\/img\/OrganicChemistry\/NamingOrganicMolecules6.question2.gif\" width=\"299\" height=\"97\" \/><\/center><\/p>\n<ol>\n<li>Methylpentene<\/li>\n<li>2-methyl-1-pentene<\/li>\n<li>2-methyl-4-pentene<\/li>\n<li>4-methyl-1-pentene<\/li>\n<\/ol>\n<p><a class=\"button button-primary q-answer\"> Reveal Answer <\/a><\/p>\n<p class=\"q-reveal\">The correct answer is D. The chain name is \u201cpentene\u201d because there are five carbons in the chain with a single double bond. The number 1 before \u201cpentene\u201d tells the location of the start of the double bond. The \u201cmethyl\u201d indicates there is a one-carbon branch, the 4 tells that the branch is located on the 4th carbon of the chain. Remember that the multiple bond dictates the direction of the number of the carbons in the chain and once the direction is determined it is used throughout the name.<\/p>\n<\/section>\n<section class=\"question\">\n<h4>Question<\/h4>\n<p>What is the name of this molecule?<\/p>\n<p><center><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/americanboard.org\/Subjects\/Images\/chemistry\/img\/OrganicChemistry\/NamingOrganicMolecules6.question3.gif\" width=\"208\" height=\"204\" \/><\/center><\/p>\n<ol>\n<li>Methylheptene<\/li>\n<li>Methylheptadiene<\/li>\n<li>1-methyl-2,3-cycloheptadiene<\/li>\n<li>5-methyl-1,2-cycloheptadiene<\/li>\n<\/ol>\n<p><a class=\"button button-primary q-answer\"> Reveal Answer <\/a><\/p>\n<p class=\"q-reveal\">The correct answer is D. The \u201ccycloheptadiene\u201d results from the seventh carbon, two double bond ring. The numbers 1 and 2 are to give the double bonds the lowest sum. You can go either clockwise or counterclockwise. Going counterclockwise the branch is on the 6th carbon; going clockwise the branch would be on the 5th carbon, so the 5th carbon is used.<\/p>\n<\/section>\n<\/section>\n<p><!-- CONTENT ENDS HERE --><\/p>\n<p><!-- UPDATE NEXT\/PREVIOUS BELOW --><\/p>\n<div class=\"advance\">\n<p><a class=\"button button-primary\" href=\"http:\/\/americanboard.org\/Subjects\/chemistry\/introduction\">\u2b05 Previous Lesson<\/a>\u00a0<a class=\"button\" href=\"http:\/\/americanboard.org\/Subjects\/chemistry\/organic-chemistry\">Workshop Index<\/a>\u00a0<a class=\"button button-primary\" href=\"http:\/\/americanboard.org\/Subjects\/chemistry\/naming-organic-molecules-containing-oxygen\">Next Lesson \u27a1<\/a><\/p>\n<\/div>\n<p><a class=\"backtotop\" href=\"#title\">Back to Top<\/a><\/p>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>\u2b05 Previous Lesson\u00a0Workshop Index\u00a0Next Lesson \u27a1 Naming Organic Molecules Objective In this lesson we will examine how alkenes, alkynes, cycloalkanes and cycloalkenes are named. Previously we covered&#8230; Organic chemistry is the study of carbon containing molecules. There are multiple ways to represent the structure of an organic molecule. Saturated molecules contain only single carbon-carbon bonds [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-560","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/americanboard.org\/Subjects\/chemistry\/wp-json\/wp\/v2\/pages\/560","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/americanboard.org\/Subjects\/chemistry\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/americanboard.org\/Subjects\/chemistry\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/americanboard.org\/Subjects\/chemistry\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/americanboard.org\/Subjects\/chemistry\/wp-json\/wp\/v2\/comments?post=560"}],"version-history":[{"count":7,"href":"https:\/\/americanboard.org\/Subjects\/chemistry\/wp-json\/wp\/v2\/pages\/560\/revisions"}],"predecessor-version":[{"id":591,"href":"https:\/\/americanboard.org\/Subjects\/chemistry\/wp-json\/wp\/v2\/pages\/560\/revisions\/591"}],"wp:attachment":[{"href":"https:\/\/americanboard.org\/Subjects\/chemistry\/wp-json\/wp\/v2\/media?parent=560"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}