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Exam I with detailed answers

Exam I with detailed answers - Name_detailedkey Place first...

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Name ______________________________     detailed key Place first 2 letters of last name here CHEM 231 Exam I Fall 2007 1. Draw the compounds described by the names given. (20) 5pts each. Each mistake –1 a ring in the alcohol case counted as 2 mistakes… most other individual errors counted once. Most scores 17 or above. Mode of scores 19. cis -2-chloro-3-ethyl-1,1-dimethylcyclopropane 4-methylhexan-3-ol bicyclo[4.1.0]heptane 5-(1-methylethyl)-2,3,8-trimethylnonane Cl Cl or most common mistakes making the 2 methyl groups upfacing (wedges); making 5 member ring instead of 3. most common mistakes: making spirocyclic; not right number of carbons in rings OH most common mistake was drawing cyclohexane instead of hexane most common mistake was to put a methyl and ethyl at carbon 5 or to try to puy those groups at 'carbon 1' 2. Give the names of the following compounds. (25) 1 pt for each error. Some errors compounded into more than 1 pt off. Average score was 18 or 19. 1
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Br bicyclo[1.1.1]pentane 2pts for each part of answer. typical problems were wrong #s; calling it spiro; calling it a propane or a hexane trans -1- sec -butyl-3-bromocyclohexane -1 for each mistake. order not counted as a mistake. most common errors were with the sec butyl nomenclature. although at least 40% correctly named it by either iupac or common name.) other common error was forgetting trans or calling trans cis. 2,3,4,7-tetramethyl-5-propylnonane -1 for each mistake. order not counted as a mistake. Common errors were miscounting or misnumbering methyl groups; misnaming the propyl and calling tetra another name. (5-cyclobutylpentyl)cyclopentane 1-cyclobutyl-5cyclopentylpentane -1 for each mistake order not counted biggest problem for students was that they counted ring carbon twice and called the chain a heptane. another problem was calling it a spiro; a number of people tried the top nomenclature but called it 1 cyclobutyl pentyl. 3. There are many constitutional isomers that can be made from the following empirical formula (C 5 H 10 O). Draw 5 of them. (15) The key was to read the problem carefully and do one setup. Linear alkanes are C n H 2n+2 and its easy to tell that oxygen does not goof up the carbons and hydrogens. You needed a ring or a double bond. From the graders point of view this was bimodal usually all correct or all incorrect. But since it was on my page I did note that a number of people would draw different conformers to be different constitutional isomers. Here are but a few of the over 30 potential correct answers. 3 for each correct one O OH OH O OH O OH and many many more 4. For each pair, indicate the one that is the most acidic by writing its corresponding letter in the 2 nd column.
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