CH 221 1st Edition Lecture 15Outline of Last Lecture I. Two Asymmetric Centers: Three StereoisomersII. Meso CompoundsIII. Asymmetric Center versus StereocenterIV. Cis-Trans IsomersV. Introduction to AlkenesOutline of Current Lecture VI. StereoisomersVII. CycloalkenesVIII. Vinylic and Allylic CarbonsIX. E, Z system of NomenclatureCurrent LectureVI. Stereoisomers are named using cis or trans prefix- Ex. Cis-2-pentene, trans-2-pentene- Two double bonds = diene- Ex. 2,4-heptadiene, 1,4-pentadiene- Number in the direction so that the functional group gets the lowest number- Ex. 4-methyl-1,3-pentene, 3-methyl-3-heptene, 4-penoxy-1-butene, 4-methyl-1,3-pentadiene- Substituents are listed in alphabetical order- Ex. 6-ethyl-3-methyl-3-octene, 5-bromo-4-chloro-1-heptene, 2,5-dimethyl-4-octeneVII. Cycloalkenes- A number is not needed to denote the position of the functional group: it is always between C1 and C2- Ex. 3-ethylcyclopentene, 4,5-dimethylcyclohexene, 4-ethyl-3-methylcyclohexene, 2-bromo-4-ethyl-7-methyl-4-octene, 6-bromo-3-chloro-4-methylcyclohexeneVIII. Vinylic- the sp2 carbon of an alkeneThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- Allylic – carbons adjacent to vinylic carbons- Double bonds have restricted rotation- Rotation around a double bond would break the π bond- Six atoms of an alkene are in the same plane- Cis-Trans isomers of alkenes can be separated and have different configurationsIX. Z = zusammen (together) E = entgege (opposite)- Relative priorities depend on atomic numbers of the atoms attached to the sp2- Ex. (2Z,4Z)-1-chloro-2,4-heptadiene, (2Z,4E)-1-chloro-2,4-heptadiene- Organic compounds can be divided into families- All members in one family react in the same way- Family compound belongs to depends on its functional
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