Udindo ndi Njira za Sodium Cyanide mu Organic Synthesis

Introduction

Sodium Cyanide (NaCN), chinthu choyera cha kristalo chomwe chimasungunuka kwambiri m'madzi, ndi maziko olimba komanso nucleophile yamphamvu, zomwe zimapangitsa kuti ikhale yothandiza kwambiri popanga zinthu zachilengedwe . Ngakhale kuti ndi poizoni kwambiri, zomwe zimafunika kusamala kwambiri posamalira, Sodium cyanide imagwira ntchito yofunika kwambiri popanga zinthu zosiyanasiyana zachilengedwe, kuphatikizapo mankhwala, mankhwala a agrochemicals, ndi ma polima.

Udindo wa Sodium Cyanide mu Organic Synthesis

Cyanide Ion ngati Nucleophile

Iyoni ya cyanide mkati mwa Sodium Cyanide ndi nucleophile yogwira ntchito kwambiri. Chifukwa cha mphamvu yoipa pa atomu ya Carbon komanso kuchuluka kwa ma electronegativity a atomu ya nayitrogeni, imatha kuukira malo ophikira ma electrophilic m'mamolekyu achilengedwe, monga magulu a carbonyl, alkyl halides, ndi epoxides.

Kupanga kwa C-C Bond

Chimodzi mwa ntchito zofunika kwambiri za sodium cyanide mu kapangidwe ka organic ndi kupanga ma bond atsopano a carbon-carbon, omwe amapezeka kudzera mu kusintha kwa nucleophilic ndi ma addition reactions. Mwachitsanzo, pamene alkyl halide imagwirizana ndi sodium cyanide, cyanide ion imalowa m'malo mwa halide ion, zomwe zimapangitsa kuti nitrile ipangidwe. Kuchita izi kumapereka njira yosavuta yowonjezerera atomu yowonjezera ya carbon mu molekyulu. Pambuyo pake, gulu la nitrile likhoza kusinthidwa kukhala magulu ena ogwira ntchito monga carboxylic acids, amines, kapena aldehydes kudzera mu njira zosiyanasiyana zamankhwala.

Kaphatikizidwe ka Amino Acids - The Strecker Reaction

Sodium cyanide ndi gawo lofunikira pakuchita kwa Strecker, komwe kumagwiritsidwa ntchito popanga α - amino acid. Pochita izi, aldehyde kapena ketone imaphatikizana ndi ammonium chloride ndi sodium cyanide kupanga α - amino nitrile. α - amino nitrile imatha kupangidwa ndi hydrolyzed kuti ipange α - amino acid yofananira.

Zomwe zimachitika zimawonekera munjira zingapo: Choyamba, gulu la carbonyl la aldehyde kapena ketone limakhala ndi protonation, ndikuwonjezera mphamvu yake ya electrophilicity. Kenako, molekyulu ya ammonia imaukira gulu la protonated carbonyl, ndikutsatiridwa ndi deprotonation kupanga hemiaminal. Kenako, gulu la hydroxyl la hemiaminal limakhala lopangidwa ndi protonated, zomwe zimapangitsa kuti madzi athetsedwe komanso kupanga ion ioni. Iyoni ya cyanide kenako imaukira ion ionium kuti ipereke α - amino nitrile. Pomaliza, hydrolysis ya α - amino nitrile pamaso pa asidi kapena maziko amapereka α - amino acid.

Kaphatikizidwe ka Nitriles kuchokera ku Aryl Halides - The Rosenmund - von Braun Reaction

Mu Rosenmund - von Braun reaction, sodium cyanide imagwiritsidwa ntchito kutembenuza aryl halides, omwe ndi halogen - m'malo onunkhira mankhwala, kukhala aryl nitriles. Kupangidwa ndi copper(I) cyanide ndipo nthawi zambiri kumafuna kutentha kwambiri, izi zimaphatikizapo kupanga mkuwa - aryl wapakatikati. Iyoni ya cyanide yochokera ku sodium cyanide ndiye imachita ndi ichi chapakatikati kupanga aryl nitrile. Izi ndizofunikira poyambitsa gulu logwira ntchito la nitrile pa mphete yonunkhira, yomwe imatha kusinthidwanso kuti apange mitundu yosiyanasiyana yamafuta onunkhira, monga mankhwala ndi utoto.

Kaphatikizidwe ka Carbonyl Compounds

Sodium cyanide nawonso amatenga nawo mbali mu kaphatikizidwe ka carbonyl mankhwala. Mwachitsanzo, ikakumana ndi epoxide, ayoni wa cyanide amaukira atomu ya carbon yocheperako ya mphete ya epoxide, ndikupangitsa mpheteyo kutseguka. Wotsatira hydrolysis wa chifukwa cyanohydrin kungachititse kuti mapangidwe carbonyl pawiri.

Njira Zochita Zokhudza Sodium Cyanide

Nucleophilic Substitution Reactions

Njira ya SN2 : Pamene sodium cyanide imagwira ntchito ndi ma alkyl halides oyambira, nthawi zambiri zimachitika motsatira njira ya SN2 (bimolecular nucleophilic substitution). Cyanide ion imaukira atomu ya kaboni yolumikizidwa ku halogen kuchokera kumbuyo, moyang'anizana ndi malo a ion ya halide yochoka. Iyi ndi njira yogwirizana pomwe kusweka kwa kaboni - halogen bond ndi kupangidwa kwa kaboni - cyanide bond zimachitika nthawi imodzi. Kuchuluka kwa reaction kumadalira kuchuluka kwa alkyl halide ndi ion ya cyanide, ndipo stereochemistry ya chinthucho imasinthidwa poyerekeza ndi ya zinthu zoyambira.

Njira ya SN1 : Ndi ma tertiary alkyl halides, reaction ingapitirire kudzera mu SN1 (unimolecular nucleophilic substitution). Choyamba, alkyl halide imalekanitsidwa ndikupanga carbocation intermediate. Kenako, cyanide ion imaukira carbocation iyi kuti ipange chinthucho. Njira ya SN1 imadziwika ndi kupangidwa kwa planar carbocation intermediate, ndipo chinthucho chikhoza kuwonetsa kusakaniza kwa stereochemistries, chinthu chodziwika kuti racemization, chifukwa cha nucleophile kuwukira kuchokera mbali zonse ziwiri za planar carbocation.

Nucleophilic Addition Reactions

Kuwonjezera pa Magulu a Carbonyl : Pamene sodium cyanide imagwirizana ndi aldehydes kapena ketones, iyoni ya cyanide imalunjika ku atomu ya carbonyl carbon carbon electriphic. Gulu la carbonyl limakhala ndi polarized carbon-oxygen bond, ndipo atomu ya carbon imakhala malo ophilic. Kuukira kwa iyoni ya cyanide kumapanga mgwirizano watsopano wa carbon-cyanide, ndipo atomu ya oxygen ya gulu la carbonyl imapeza mphamvu yoipa. Mu sitepe yotsatira, gwero la proton, monga madzi kapena asidi, limapanga atomu ya oxygen kuti ipange cyanohydrin. Kuchita izi kumatha kusinthidwa, ndipo kufanana kumatha kusinthidwa ku chinthucho powongolera momwe zinthu zimachitikira.

Kuwonjezera pa Imines : Mu Strecker reaction, kuwonjezera kwa cyanide ion ku iminium ion, yomwe imapangidwa kuchokera ku reaction ya aldehyde kapena ketone yokhala ndi ammonia, kumatsatira njira yofanana yowonjezerera nucleophilic. Iminium ion ili ndi mphamvu yabwino pa atomu ya nayitrogeni, zomwe zimapangitsa atomu ya kaboni yoyandikana nayo kukhala yamagetsi. Iyoni ya cyanide imaukira atomu ya kaboni iyi, ndikupanga chomangira chatsopano cha kaboni-cyanide zomwe zimapangitsa kuti pakhale α-amino nitrile.

Zilingaliro Za Chitetezo

Ndikofunikira kutsindika kuti sodium cyanide ndi poizoni kwambiri. Kukoka mpweya, kuwameza, kapena kukhudza nawo khungu kumatha kupha. Pogwira ntchito ndi sodium cyanide, ndondomeko zotetezera ziyenera kutsatiridwa. Izi zikuphatikiza kuyesa mu hood yolowera mpweya wabwino, kuvala zida zodzitetezera zoyenera monga magolovesi, magalasi, ndi jasi la labu, komanso kukhala ndi mapulani oyenera kuthana ndi vuto ladzidzidzi ngati atakumana mwangozi.

Kutsiliza

Sodium cyanide ndi reagent yamphamvu komanso yosunthika mu organic synthesis. Kutha kwake kuchita ngati nucleophile ndikupanga ma carbon - carbon bonds atsopano kumapangitsa kuti ikhale chida chofunikira kwambiri kwa akatswiri opanga mankhwala popanga mitundu yambiri yamagulu achilengedwe. Kumvetsetsa njira zomwe zimakhudzana ndi sodium cyanide ndikofunikira kuti mupange njira zopangira bwino komanso kulosera zomwe zidzachitike. Komabe, chifukwa cha kawopsedwe kake, kagwiritsidwe ntchito kake kuyenera kuyendetsedwa mosamalitsa ndikuchitidwa mosamala kwambiri kuti muteteze moyo wa akatswiri azamankhwala komanso chilengedwe.