CHEM 2211 1st Edition Lecture 15 Outline of Last LectureI. Protons bonded to Oxygen and NitrogenII. Deuterium in HNMRIII. CNMR SpectroscopyOutline of Current LectureI. Alkenes have double bondsII. NomenclatureCurrent LectureI. Alkenes have double bondsA. The general formula for an alkene is CnH2nB. Alkenes have two less carbons than alkanesC5H12C5H10C. Degree of unsaturation refers to the number of pi bonds presentD. Alkanes are considered saturated because they have the maximum number of bondsE. The presence of pi bonds means the carbon is unsaturatedII. NomenclatureA. Replace the –ane at the end of an alkane name with –ene B. Number the parent chain in an order that gives the functional group the lowest number (double bond counts as a functional group)1-butene2-butenei. Use cis and trans for stereoisomerscis-2-pentenetrans-2-penteneC. For molecules with two double bonds replace –ene with –diene1, 4-pentadieneD. Substituents are stated before the parent chain name. The functional group on the parent chain always gets the lowest number.4-pentoxy-1-butene4-methyl-1, 3-pentadieneE. Multiple substituents are stated in alphabetical order (for further review, refer to Section 3.2 in the book)5-bromo-4-chloro-1-heptaneF. If same number is found for two substituents when numbered both ways, then the way with the lowest substituent number wins2-bromo-4-methyl- 3-hexeneNOT5-bromo-3-methyl-3-hexeneG. Double bonds in a ring are always labeled as carbons one and two, then count ot give the substituents the lowest number 3-ethylcyclopenteneH. 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.6-bromo-3-chloro-4-methylcyclohexene NOT 3-bromo-6-chloro-3-methylcycohexenei. Sp2 carbons are called vinyl carbons and their adjacent carbons are called allylic carbonsVinyl CarbonsAllylic CarbonsI. Using the E and Z methodi. Similar to cis and trans nomenclatureii. E/Z nomenclature refers to the orientation of the highest priority substituents when the substituents are not the sameiii. E means that the substituents are on the same sideiv. Z means the substituents are on the opposite sidev. Priority is based on the atomic
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