{"id":1762,"date":"2012-08-30T23:09:02","date_gmt":"2012-08-31T06:09:02","guid":{"rendered":"http:\/\/wordpress.reed.edu\/chem201202\/2012\/08\/learning-activity-2---corrections.html"},"modified":"2014-03-18T10:13:01","modified_gmt":"2014-03-18T17:13:01","slug":"learning-activity-2-corrections","status":"publish","type":"post","link":"https:\/\/blogs.reed.edu\/chem201202\/2012\/08\/learning-activity-2-corrections\/","title":{"rendered":"Learning Activity #2 &#8211; Corrections"},"content":{"rendered":"<p>\n\tSome corrections and clarifications for Learning Activity #2 follow. Let me know if you have other suggestions.<\/p>\n<ul>\n<li>\n\t\t#DU. A ring and a double-bond both count as 1 DU. Consider some three-carbon compounds. CH3CH2CH3 is propane, the saturated molecule. CH2=CHCH3 is C3H6. This molecule is one H2 short of saturation (1 DU). Cyclopropane, (CH2)3, contains only single bonds in a three-atom ring. Because its molecular formula is C3H6, it is also one H2 short of saturation (1 DU).<\/li>\n<li>\n\t\tModel 4. The definition of <strong>alkane<\/strong> might be reworded to make it clearer. Let&#039;s try <strong>alkane = saturated hydrocarbon<\/strong>.<\/li>\n<li>\n\t\tFact 2.3 gives an incomplete definition of <strong>branched<\/strong> alkane. A branched alkane must contain at least one methine (CH) group OR one quaternary C.<\/li>\n<li>\n\t\tThe right-hand structure in Fig. 2.5 is incorrect. Add another CH3 group to the left end of the molecule so that there are 8 C&#039;s in the chain.<\/li>\n<li>\n\t\tRe-word Q#19 to read, &quot;Circle each <strong>group of<\/strong> C in Fig. 2.5 &#8230;&quot;. The idea is to draw a single circle around each alkyl substituent.<\/li>\n<li>\n\t\tQ#20-22 might lead to some confusion (Sorrell will straighten you out). An alk<u><strong>ane<\/strong><\/u> is a molecule in which all of the C and H bonding patterns are obeyed. An alk<u><strong>yl<\/strong><\/u> group contains one C with only three bonds, a rule violation. Thus, meth<strong><u>yl<\/u><\/strong> is derived from meth<strong><u>ane<\/u><\/strong>. Q#20-21: the suffix that methyl and ethyl share is <strong>&#039;yl&#039;<\/strong>, not &#039;ethyl&#039;. Applying this in Q#22 leads to CH3CH2CH2 = prop<strong><u>yl<\/u><\/strong> and so on.<\/li>\n<\/ul>\n<p>\n\t<strong>Friday, Aug 31 update.<\/strong> Several students called my attention to an apparent contradiction in Model 6 and Fig. 2.6. The molecule on the left is named 2-ethyl-1,4-dimethylcyclohexane. This name appears to contradict the rule given in Model 6 that states, &quot;C#1 is the ring carbon bonded to the substituent that comes first in the alphabet (prefixes like &ldquo;di&rdquo; and &ldquo;<em>sec-<\/em>&rdquo; are ignored)&quot;. The rule suggests &#039;ethyl&#039; is located at C#1, but the name that was provided clearly assigns a methyl to C#1.<\/p>\n<p><!--more--><\/p>\n<p>\n\tI have checked various sources to see where I found this molecule and this rule. <u>I believe the molecule is named correctly<\/u> so I must have given you the wrong rule. I have found a book that says, &quot;If there are <strong>exactly two<\/strong> alkyl groups, decide which C gets &quot;1&quot; based on alphabetical order&quot;. This rule doesn&#039;t apply here, however, because there are <u>three<\/u> alkyl groups. The same book also says, &quot;[groups] are listed in a name alphabetically (not including prefixes di, tri, <em>sec<\/em>, or <em>tert<\/em>)&quot;, but this rule refers to the position of groups in the name and not the numbering of the ring. So I can&#039;t find any basis for the rule I gave you (except when there are exactly two alkyl groups) and I think <u>my error<\/u> was to combine two statements from my reference book into one. Yikes.<\/p>\n<p>\n\tFortunately, you are not being asked to learn how to assign names to formulas so I hope this error won&#039;t cause too much confusion.<\/p>\n","protected":false},"excerpt":{"rendered":"<p> Some corrections and clarifications for Learning Activity #2 follow. Let me know if you have other suggestions. #DU. A ring and a double-bond both count as 1 DU. Consider some three-carbon compounds. CH3CH2CH3 is propane, the saturated molecule. CH2=CHCH3&#8230;<\/p>\n","protected":false},"author":55,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3],"tags":[],"class_list":["post-1762","post","type-post","status-publish","format-standard","hentry","category-post-lecture"],"_links":{"self":[{"href":"https:\/\/blogs.reed.edu\/chem201202\/wp-json\/wp\/v2\/posts\/1762","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blogs.reed.edu\/chem201202\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blogs.reed.edu\/chem201202\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blogs.reed.edu\/chem201202\/wp-json\/wp\/v2\/users\/55"}],"replies":[{"embeddable":true,"href":"https:\/\/blogs.reed.edu\/chem201202\/wp-json\/wp\/v2\/comments?post=1762"}],"version-history":[{"count":2,"href":"https:\/\/blogs.reed.edu\/chem201202\/wp-json\/wp\/v2\/posts\/1762\/revisions"}],"predecessor-version":[{"id":5108,"href":"https:\/\/blogs.reed.edu\/chem201202\/wp-json\/wp\/v2\/posts\/1762\/revisions\/5108"}],"wp:attachment":[{"href":"https:\/\/blogs.reed.edu\/chem201202\/wp-json\/wp\/v2\/media?parent=1762"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.reed.edu\/chem201202\/wp-json\/wp\/v2\/categories?post=1762"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.reed.edu\/chem201202\/wp-json\/wp\/v2\/tags?post=1762"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}