CHEM 2211 Exam # 1 Study Guide Lectures: 9-19Lecture 9 (6 September)I. Single bonds rotate about themselves giving rise to geometric isomersa. Cis-isomers have substituent on the same sideb. Trans-isomers have substituents on opposite sidesc. Each molecule has a different form of reactivityII. Conformations are different spatial arrangements while configurations are different compoundsIII. Chiral molecules are molecules that are non-superimposable, mirror images of themselves (similar to left and right hand)a. The result of carbon bonded to four different substituentsb. Achiral molecules are superimposable mirror images of each otherIV. Enantiomers are molecules that cannot be superimposed on each other but are mirror images of each othera. When drawing enantiomers remember that the hatched wedge means the bond is receding into the paper and that the wedge means the bond is sticking out at youV. Fisher projections show that bonds intersect at a vertical carbona. Vertical lines are bonds extending backwards and horizontal lines are bonds extending forwardsVI. R,S naming system determines the direction of the chiral centera. Rank the substituents in order of highest to lowest priority based on their atomic weight i.e. O > Nb. If lowest priority group is on hatched wedge then draw an arrow from highest priority to lowest. It’s an R configuration if the arrow is clockwise and S configuration if the arrow is counterclockwise.c. If lowest priority is not on the hatched wedge then the switch it with the highest priority one and follow the steps presented above.Lecture 10 (9 September)I. Though enantiomers have similar properties they interact differently with plane polarized lightA. Achiral molecules do NOT rotate lightB. Dextrorotary molecules rotate light to the rightC. Levorotary molecules rotate light to the leftD. The specific rotation of a molecule is the measure of the amount of rotation caused by pure liquid or 1.00g of material dissolved in 100 mLE. This equation is used to determine the amount of rotation light has done[∝]λT=∝l x cF. A racemic mixture is the mixture of equal parts of both enantiomers. These mixtures yield a rotation of zeroII. Enantiomeric Excess tells us how pure a mixture is via this equationenatiomeric excess=observed specific rotationspecific rotationof the pure enantiomerx 100 %Example: 2-bromobutane has a specific rotation of +23.1. An experiment yielded that a 2-bromobutane mixture has an observed specific rotation of +9.2.enatiomeric excess=+9.2+23.1x 100 %=40 %This means that 40% of the mixture is excess S enantiomers and 60% is a racemic mixture meaning a total of 70% [40% + ½ (30%)] is S enantiomer and the remaining 30% is R enantiomer.A. Observed specific rotation is the rotation of the sameB. Enantiomerically pure compounds only have one enantiomerIII. Compounds with more than one asymmetric center can be diastereomers in which they are neither identical nor mirror imagesA. Diastereomers have different physical and chemical propertiesB. Erythro enantiomers have hydrogens on the same sideC. Threo enantiomers have hydrogens on the opposite sideLecture 11 (11 September)I. Some cyclic compounds have stereoisomers but some do not because they have substituents placed an equal distance from each otherII. Meso compounds are asymmetric centers with a line of symmetry running through the molecule. They are achiral and also optically inactiveIII. Name molecules with multiple asymmetric centers the same as with one asymmetric center, but remember to specify which carbon has the asymmetric centerLecture 12 (13 September)I. HNMR is the measure of the number of molecules aligned with and against a magnetic fielda. Shielding affects the signal graphedi. Shielding refers to the number of electrons around the molecule. If an atom is around another very electronegative atom then the atom with be less shielded.ii. More shielded molecules are upfield (right) and less shielded are downfiled (left)b. Chemically equivalent hydrogens produce the same signalc. Chemical shift is the measure of how far the signaled is from the reference compound, TMSLecture 13 (16 September)I. The area under the HNMR spikes is equivalent to the number of hydrogens in the compoundII. Signal splitting occurs when nonequivalent hydrogens on adjacent carbons emit a signal that interferes with other hydrogensa. N+1 rule is the number of hydrogens on nonequivalent neighboring carbons + 1= number of peaks on graphb. Hydrogens on prochiral centers are equivalentc. Hydrogens on chiral centers are notLecture 14 (18 September)I. –OH shows up very broad on NMR graphs if it shows a signalII. Deuterium is used to determine the signal of a molecule because it doesn’t show up on HNMRIII. CNMR records the signals of Carbon-13 and requires an FT-NMR because the CNMR graph is an average of multiple scansIV. Shows up as singlets in decoupled CNMR but shows as splitting on proton-coupled CNMRLecture 15 (20 September)I. Alkenes have unsaturated carbons because they have a double bondA. Degree of unsaturation is dependent upon number of pi bondsII. Nomenclature is the same for alkanes but the parent ending is –eneA. Number the parent chain in an order that gives the functional group the lowest number (double bond counts as a functional group)i. Use EZ nomenclature as opposed to cis/transB. For molecules with two double bonds replace –ene with –dieneC. Substituents are stated before the parent chain name. The functional group on the parent chain always gets the lowest number.D. Multiple substituents are stated in alphabetical order (for further review, refer to Section 3.2 in the book)E. If same number is found for two substituents when numbered both ways, then the way with the lowest substituent number winsF. Double bonds in a ring are always labeled as carbons one and two, then count to give the substituents the lowest number G. If the same number is found for alkene functional groups and for one or more substituents, ignore the conflicting substituents and number in a way that gives the remaining substituent the lowest number.i. Sp2 carbons are called vinyl carbons and their adjacent carbons are called allylic carbonsIII. Using the E and Z methodA. E/Z nomenclature refers to the orientation of the highest priority substituents when the substituents are not the sameB. E means that the substituents are on the same sideC. Z means the substituents are on the opposite sideD. Priority is based on