Ch 9 - Alkynes

Ch 9 Alkynes - A l kynes 9 H H 9 1 Alkynes Introduction are hydrocarbons that contain carbon-carbon triple bonds Alkynes are also called acetylenes

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9 Alkynes 9-1 Introduction 382 H H Alkynes are hydrocarbons that contain caRbon-carbon tRiple bonds. Alkynes aRe aLso ca±led acetylenes because they are derIvatIves of acety±ene, the sImp±est a±kyne² H³C=C³H acetylene ethyne CH3CH2´C ³ C´H ethyl acetylene I-butyne CH3´C=C³CH3 di methy Lacety lene 2±bUtyne The chemistry of the carbonµcarbon trIple bond Is sImIlar to that of the doub±e bond. ¶n this chapteR· we see that a±kynes undeRgo most of the same reactIons as a±kenes¸ especia±±y the addItions and the oxIdatIons. We a¹so ºonsIdeR ReactIons tha» aRe specIF¼c to a±kynes: some that depend on the unique chaRacteristics of the C ´ C tRIple bond, and otheRs that depend on the unusual acIdity of the acetylenIc C ³H bond½ A triple bond gIves an a±kyne four feweR hydrogens than the corResponding alkane¾ ¿ts molecu±aR formu±a is ±ike that of a molecu±e wIth two double bondsÀ C N H 2N Á 2 TheReà foRe, the triple bond contRIbutes two elements of unsaturatioÄ (eu) (SectIon 7ÅÆ)Ç H 'ÈÉ / H H³C³C³H H / ÊËÌ ethane, C2H6 o eu² C Il H ± 1l + 2 H 'ÈÉ / H / CÍC 'ÈÉ H H ethene, C2H4 ³eu² C iL H ± ²L H´CÎC´H Ethyne´ C±H± 2 eu µ C nh³´l _ ± Alkynes are not as common In natuRe as alkenes, but some plants do use alkynes to protect themse±ves against dIsease or pRedatoRs. ÏIcutoxIn is a toxIc compound foUnd In wateR hemlockÐ and capi±Lin pRotects a plant against funga± diseases. The alkyne funcà tIona± gRoup Ñs not common in dRugs, but parsa±mide is used as an anaÒgesic, and ethynyÓ estRadIol (a synthetIc fema±e hoÔÕone) is a common IngRedIent In biRth contÖO× pIlLs. DynemicIn A Is an antIbacterIaL compound that Is being tested as an antItumoR agent½ HØCHÙCHÙCHÙ³CÚC´CÎC´CHÛCH´CHÍCH´CHÛCH³CHCHÙCHÜCHÝ I cicutox¶n ØH o 11 - CHݳCÚC³CÚC´C j capil³in
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9-2 Nomenclature of Alkynes 383 HO parsalmide ethynyl estraDIOL PROBLEM 9-1 ±Raw StRuctuRa² foRMulaS of at least Two alkyNes Of eacH ³oleculaR foR³ula. (a) C6h I (b) C S h l2 (c) C7±io OH ² OH dynE´µCin A ² I cOH IUPAC Names The IUPAC nomenCLa±ure for aLkynes is simi²ar ³o ±ha± for a²kenes. We FInd ±he ²onges± Con±inuous Chain of Carbon a±oms ±hat inC²udes ±he tr´p²e bond and Change ±he -ane ending of the paren± a²kane ±o ±yne. The Chain is nuMbered from the end C²oses± ±o ±he ±r´pLe bond, and ±he posi±ion of ±he µ¶·p²e bond is designated by i±s ²ower- nuMbered Carbon a±om¸ Subs±i±uen±s are given nuMbers to indiCa±e ±heir ²oCa±ions¹ 9-2 Nomenclature of Alkynes Ch3 Br I I h-C ³ C-h Ch´³C - C³h Ch3-C - C³Ch´ Ch´³Ch³C - C³Chµ-Ch-Ch3 ¶UPAC name: et¶yne (aCetylene) prOpyne 2-bu·yne but - 2 - yn e 6¸brOmO¸2¹1º»et¼ y ½¹3¾¼eptyne 6 ¹ brOmO ¿ 2 ¹ met¼ y e pt - 3 - y n e When add´±ionaL funCtiona² groups are presen±º the su»xes are CoMbined ±o pro- duCe the CoMpound naMes of ±he alkenynes (a doubLe bond and a ±rip²e bond)¼ alKYnols (a trip²e bond and an aLCoho²)½ and so on. The new IUPAC
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This note was uploaded on 02/27/2010 for the course CHEM 140 taught by Professor Wade during the Spring '10 term at Whitman.

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Ch 9 Alkynes - A l kynes 9 H H 9 1 Alkynes Introduction are hydrocarbons that contain carbon-carbon triple bonds Alkynes are also called acetylenes

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