unit (7) organic compounds

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Practice 7-5Give the IUPAC name for each of the following:CH 2 - CH 3a) CH 2 = CH -CH 2 - CH 3 b) CH 3 - CH 2 -CH 2 - C = CH 2CHCH 3 CH 33c) d) CH 3 - C C - CH - CH - CH - CH 3AnswerCH 3a)1-buteneb) 2-ethyl-1-pentenec) 3-methylcyclohexene d) 4,5,6-trimethyl-2-heptyneCommon Names (non-IUPAC Names)A small number of organic compounds have common names (non-IUPAC) that are usedalmost exclusively to identify them. These compounds are usually the smallest membersof a particular class often containing only a few carbons. You need to be familiar to thesenames.CH 2 = CH 2 HC ≡ CHIUPAC name ethene ethyneCommon name ethylene acetylene7.9 Geometric IsomersUnlike alkanes, there is no free rotation around a carbon-carbon double bond in alkenes.If both carbons of the double bond have two different groups attached, cis and transisomers exist.Cis isomer: two substituted groups are on the same side of double bond.Trans isomer: two substituted groups are on opposite sides of double bond.7-14
Consider ethene:HHCCHHIf one of the hydrogen atoms attached to each of the carbon atoms in ethene is replacedby a bromine atom, two distinct compounds are formed:BrCCBrBrCCHHHHBrcis-1,2-dibromoethene(bromines on same side)trans-1,2-dibromoethene(bromines on different sides)This type of isomerism is called cis-trans isomerism. The prefix cis- and trans- arederived from the Latin; cis- “on this side” and trans- “across.”Worked Example 7-8Give the name of the following alkenes, using cis or trans.CH 3C = CCH 2 CH 3CH 3C = CH H HCH 2 CH 3(a)(b)Solutiona) The longest chain has 5 carbons with the double bond starts at carbon 2.The name is 2-pentene. The two identical groups (the hydrogen atoms) are onthe same side of the double, so we use the prefix “cis”.The full name is cis-2-pentene.b) The longest chain has 5 carbons with the double bond starts at carbon 2.The name is 2-pentene. The two identical groups (the hydrogen atoms) are onthe opposite side of the double bond, so we use the prefix “trans”.The full name is trans-2-pentene.H7-15
Page 6 and 7: Worked Example 7-2Draw all structur
Page 8 and 9: Worked Example 7-4Name the followin
Page 10 and 11: 7.5 CycloalkanesA cycloalkane is an
Page 12 and 13: 2. Halogenation is a reaction betwe
Page 16 and 17: 7.10 Reactions of AlkenesThe most c
Page 18 and 19: The word aromatic originally referr
Page 20: 7.5 Write equations for the reactio

unit (7) organic compounds

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