NAME Student ID Circle your TA s name Danny Jos CHEM 30A Winter 2006 Midterm Exam 1 February 3 2006 READ THIS FIRST The exam consists of 7 questions on 7 pages For all questions show your work and give the answers to the correct number of significant figures and units Chemical names must be spelled correctly for full credit Be sure to state any assumptions You must show your work and it must be legible for you to receive credit Indicate clearly if your work continues onto the back of a page Please sign the honor statement below before beginning The answers in this examination booklet are entirely my own work I neither gave nor received information or assistance in writing this examination I understand that sharing information during this examination or using materials not explicitly allowed by the instructor will result in a failing grade on this exam and possibly in additional action that may affect my ability to continue attending UCLA SIGNATURE G orxn R 8 314 J K 1 mol 1 R 0 0821 L atm mol 1 K 1 1 kcal 4 184 kJ k B 1 381 10 23J K 1 1 erg 10 7 J 1 L atm 101 325 1 Noggin 142 1 cm3 Firkin US 0 833 Firkin Brit G H TS GT P H T S G Go RTln Q Go RTln K products Gof reactants Gof Question Credit 1 13 2 9 3 10 4 19 5 21 6 19 7 9 Score NAME Page 2 of 10 BONUS 5 TOTAL 100 5 Points this page Name Page 2 of 10 1 13 pts total Below left is the structure of vanillin H O a 6 Name the functional groups b 2 What is the most polar bond OCH3 OH c 1 How many carbonyl groups are there d 2 What is the hybridization of the carbon marked with the black spot e 2 On the structure mark a large next to any stereocenters Points this page Name Page 3 of 10 2 9 pts a 6 Draw resonance forms for related HCOCH2 and use arrow notation to show how they are b 3 Which of the two resonance structures makes a greater contribution to the hybrid Indicate A or B in the box at right or write EQUAL if they contribute equally N N A B 3 10 pts a 4 In the box below draw CH3 showing the bonding orbitals and any unfilled partially filled or filled orbitals b 4 This species is circle answer s a carbanion a nucleophile a carbocation an electrophile a radical an atropisomer of CH3 c 2 The hybridization of the carbon atom is Points this page Name Page 4 of 10 4 19 pts breakdown deliberately not specified do not ask a Which of the following have non zero dipole moments Write the letter s in the box at right N Et 3 A CH3OCH3 trans 1 4 dichlorocyclobutane B C Note There is a typographic error in the name of this compound It should have read trans 1 2 dichlorocyclobutane The Key explains how this question was graded b In each box at right write the IUPAC name for the following compounds You do not need to give absolute configurations R S notation O Br c In each box at right draw the correct framework structure of the following compounds cis 1 3 dibromocyclopentane 2 methyl 4 1 methylethyl heptane Points this page Name Page 5 of 10 5 21 pts a 6 Indicate whether each molecule drawn below is chiral or achiral by writing CHIRAL or ACHIRAL in the box Cl Cl C H H Br b 15 For each of the following pairs of molecules state in the box at right whether the molecules are CONSTITUTIONAL ISOMERS CIS TRANS ISOMERS ENANTIOMERS IDENTICAL or NONE of these CH3 CH3 CH3 CH3 Br OH HO Br OH OH Cl Cl CH3 H CH3 CH3 H H OH H CH3 H HO H Points this page Name Page 6 of 10 Points this page Name Page 7 of 10 6 19 pts a 8 Draw the two chair conformers of cis 1 chloro 3 isopropylcyclohexane that exist in equilibrium at 20 C b 2 Circle the box containing the stable conformer c 3 What is the difference in energy of the two conformers Write your answer in the box at right below axial equatorial G 1 kJ mol group CH3 CH2CH3 CH CH3 2 C CH3 3 Cl axial to equatorial 7 28 7 3 9 0 21 0 2 2 NOTE The following questions are NOT related to one another or the questions above d 4 What is a transition state brief definition in the box please 3 2 Circle the compound in which the carbon in bold has the highest oxidation state CH3CHO H3COCH3 CH3COOH Points this page Name Page 8 of 10 7 9 Consider the following compound CH3 H H CA CB H Cl iPr a 3 In the box at right draw the Newman projection for the least favorable conformation about the CA CB bond b 3 In the box at right draw the Newman projection for the most favorable conformation about the CA CB bond c 1 Upon rotating about the CA CB bond what type of strain if any is encountered If none write NONE d 2 On the structure above mark a large next to any stereocenters Bonus 5 pts all or nothing In the box briefly state Hammond s postulate for an exothermic reaction that occurs in a single step Points this page Name Page 9 of 10 THE END Points this page