{"id":14,"date":"2008-07-09T09:22:29","date_gmt":"2008-07-09T13:22:29","guid":{"rendered":"http:\/\/www.ibchem.com\/faq\/?p=10"},"modified":"2008-07-09T09:22:29","modified_gmt":"2008-07-09T13:22:29","slug":"how-can-i-test-for-an-alcohol","status":"publish","type":"post","link":"https:\/\/www.ibchem.com\/blog\/2008\/07\/09\/how-can-i-test-for-an-alcohol\/","title":{"rendered":"How can I test for an alcohol?"},"content":{"rendered":"<p>May 21st, 2007<br \/>\nTo detect the presence of the OH group regardless there are several simple tests that can be done, however they all have the disadvantage of interference by water.<br \/>\nA small piece of sodium metal can be placed in the alcohol and a steady stream of hydrogen bubbles gives a positive indication. Remember that the presence of water will also cause hydrogen to be evolved.<br \/>\nThe suspected alcohol may be mixed with some PCl<sub>5<\/sub> and the evolution of misty HCl gas is a positive indication of an OH group. Once again water interferes.<br \/>\n\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014<br \/>\nPrimary, secondary and tertiary alcohols<br \/>\nThere are three different types of alcohol depending on what is attached to the carbon holding the OH group.<br \/>\n\u00b7 Primary &#8211; one alkyl group attached to the carbon holding the -OH<br \/>\n\u00b7 Secondary &#8211; two alkyl groups attached to the carbon holding the -OH<br \/>\n\u00b7 Tertiary alcohols &#8211; three alkyl groups attached to the carbon holding the -OH<br \/>\nTo differentiate between the three it is possible to use oxidation with sodium dichromate in dilute sulphuric acid and heat.<br \/>\nThe 1\u00ba alcohol oxidises to an aldehyde (alkanal) and then to a carboxylic acid (alkanoic acid)<br \/>\nThe 2\u00ba alcohol oxidises to a ketone (alkanone) and stops there.<br \/>\nThe 3\u00ba alcohol cannot be oxidised under these conditions.<br \/>\nAnother (infrequently used) test is Lucas\u2019 test for 1\u00ba, 2\u00ba, 3\u00ba alcohols.<br \/>\nIt involves shaking the alcohol with ZnCl<sub>2<\/sub> and dilute HCl. The 3\u00ba alcohol goes cloudy almost at once, the 2\u00ba alcohol goes cloudy after a few minutes whereas the 1\u00ba alcohol needs concentrated HCl to go cloudy. The cloudiness is due to the formation of the haloalkane that is immiscible with the aqueous solution of the zinc chloride and forms tiny droplets of an organic phase within the aqueous phase.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>May 21st, 2007 To detect the presence of the OH group regardless there are several simple tests that can be done, however they all have the disadvantage of interference by water. A small piece of sodium metal can be placed in the alcohol and a steady stream of hydrogen bubbles gives a positive indication. Remember [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[9],"tags":[20,59,70,74,79,89,101,108],"class_list":["post-14","post","type-post","status-publish","format-standard","hentry","category-organic","tag-alcohol-test","tag-lucas","tag-oxidation","tag-pcl5","tag-primary","tag-secondary","tag-tertiary","tag-zncl2"],"_links":{"self":[{"href":"https:\/\/www.ibchem.com\/blog\/wp-json\/wp\/v2\/posts\/14","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.ibchem.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.ibchem.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.ibchem.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.ibchem.com\/blog\/wp-json\/wp\/v2\/comments?post=14"}],"version-history":[{"count":0,"href":"https:\/\/www.ibchem.com\/blog\/wp-json\/wp\/v2\/posts\/14\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.ibchem.com\/blog\/wp-json\/wp\/v2\/media?parent=14"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ibchem.com\/blog\/wp-json\/wp\/v2\/categories?post=14"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ibchem.com\/blog\/wp-json\/wp\/v2\/tags?post=14"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}