Karolo le Mekhoa ea Sodium Cyanide ho Organic Synthesis

Selelekela

Sodium Nako (NaCN), kristale e tšoeu e tiileng e qhibilihang haholo metsing, ka bobeli ke motheo o matla le nucleophile e matla, e etsang hore e be reagent ea bohlokoa Motsoako oa lintho tse phelang. Leha e na le chefo e feteletseng, e hlokang mehato e tiileng ea polokeho nakong ea ts'ebetso, Sodium cyanide e bapala karolo ea bohlokoa ho hlahisoeng ha metsoako e fapaneng ea lintho tse phelang, ho kenyeletsoa meriana, lik'hemik'hale tsa temo le lipolymers.

Karolo ea Sodium Cyanide ho Organic Synthesis

Cyanide Ion e le Nucleophile

The cyanide ion ka hare Sodium cyanide ke nucleophile e arabelang haholo. Ka lebaka la tjhaja e mpe ho k'habone athomo le ho ba le electronegativity e phahameng ea athomo ea naetrojene, e ka hlasela litsi tsa electrophilic limolek'huleng tsa lintho tse phelang, tse kang lihlopha tsa carbonyl, li-alkyl halides le li-epoxide.

Ho thehoa ha C - C Bonds

E 'ngoe ea mesebetsi ea bohlokoa ka ho fetisisa ea sodium cyanide ka har'a organic synthesis ke ho theoa ha li-carbon bond tse ncha, tse fihletsoeng ka ho kenya sebaka sa nucleophilic le karabelo ea tlatsetso. Ka mohlala, ha alkyl halide e kopana le sodium cyanide, ion ea cyanide e nkela halide ion sebaka, e leng se lebisang ho thehoeng ha nitrile. Karabelo ena e fana ka mokhoa o bonolo oa ho kenyelletsa athomo e eketsehileng ea carbon ka har'a molek'hule. Ka mor'a moo, sehlopha sa nitrile se ka fetoloa lihlopha tse ling tse sebetsang tse kang carboxylic acid, amine, kapa aldehydes ka mekhoa e fapaneng ea lik'hemik'hale.

Synthesis ea Amino Acids - The Strecker Reaction

Sodium cyanide ke karolo ea bohlokoa ho karabelo ea Strecker, e sebelisetsoang ho kopanya α - amino acid. Karabelong ena, aldehyde kapa ketone e kopana le ammonium chloride le sodium cyanide ho etsa α - amino nitrile. Joale α - amino nitrile e ka etsoa hydrolyzed ho hlahisa α - amino acid e tšoanang.

Boitšoaro bo hlaha ka mehato e mengata: Ea pele, sehlopha sa carbonyl sa aldehyde kapa ketone se etsa protonation, se eketsa electrophilicity ea sona. Joale, molek’hule ea ammonia e hlasela sehlopha sa protonated carbonyl, e lateloang ke deprotonation ho etsa hemiaminal. Ka mor'a moo, sehlopha sa hydroxyl sa hemiaminal se hlahisoa ka protonated, e leng se etsang hore ho felisoe metsi le ho thehoa ha an ion ion. Joale ion ea cyanide e hlasela ion ionium ho hlahisa α - amino nitrile. Qetellong, hydrolysis ea α - amino nitrile boteng ba asiti kapa setsi se fana ka α - amino acid.

Synthesis of Nitriles from Aryl Halides - The Rosenmund - von Braun Reaction

Karabelong ea Rosenmund - von Braun, sodium cyanide e sebelisoa ho fetolela aryl halides, e leng metsoako ea halogen e nkeloang sebaka ke monko o monate, hore e be aryl nitriles. E hlahisoa ke koporo(I) cyanide mme hangata e hloka mocheso o phahameng, karabelo ena e kenyelletsa ho etsoa ha koporo - aryl bohareng. Ion ea cyanide e tsoang sodium cyanide e ntan'o itšoara le sena bohareng ho etsa aryl nitrile. Ts'ebetso ena e bohlokoa bakeng sa ho kenyelletsa sehlopha sa ts'ebetso ea nitrile holim'a selikalikoe se nkhang hamonate, se ka fetoloang ho ea pele bakeng sa motsoako oa metsoako e fapaneng e nkhang hamonate, joalo ka meriana le dae.

Motsoako oa Metsoako ea Carbonyl

Sodium cyanide e boetse e kenya letsoho tlhahisong ea metsoako ea carbonyl. Ka mohlala, ha e kopana le epoxide, ion ea cyanide e hlasela athomo ea carbon e nyenyane e nkeloang sebaka ea selikalikoe sa epoxide, e leng se etsang hore selikalikoe se bulehe. Hydrolysis e latelang ea cyanohydrin e hlahisoang e ka lebisa ho thehoeng ha motsoako oa carbonyl.

Mekhoa ea ho itšoara ka Sodium Cyanide

Nucleophilic Substitution Reactions

Mokhoa oa SN2: Ha sodium cyanide e sebetsana le alkyl halides ea mantlha, karabelo hangata e latela mochini oa SN2 (bimolecular nucleophilic substitution). Ion ea cyanide e hlasela athomo ea carbon e khomaretsoeng ho halogen ho tloha ka morao, e fapaneng le boemo ba ion ea halide e tlohang. Ena ke karabelo e kopaneng moo ho khaoha ha carbon - halogen bond le ho thehoa ha carbon - cyanide bond ho etsahala ka nako e le 'ngoe. Sekhahla sa karabelo se ipapisitse le likhakanyo tsa alkyl halide le ion ea cyanide, 'me stereochemistry ea sehlahisoa e fetotsoe ha e bapisoa le ea thepa e qalang.

Mokhoa oa SN1: Ka li-alkyl halides tse phahameng, karabelo e ka 'na ea tsoela pele ka mochine oa SN1 (unimolecular nucleophilic substitution). Taba ea pele, alkyl halide e ikarola ho theha sebaka sa mahareng sa carbocation. Joale, ion ea cyanide e hlasela carbocation ena ho etsa sehlahisoa. Mochine oa SN1 o khetholloa ka ho thehoa ha planar carbocation intermediate, 'me sehlahisoa se ka bontša motsoako oa stereochemistries, ketsahalo e tsejoang e le racemization, ka lebaka la ho hlasela ha nucleophile ho tloha mahlakoreng ka bobeli a planar carbocation.

Nucleophilic Addition Reactions

Keketso ho Lihlopha tsa Carbonyl: Ha sodium cyanide e sebetsana le aldehydes kapa ketone, ion ea cyanide e lebisa athomo ea carbonyl carbonyl ea electrophilic. Sehlopha sa carbonyl se na le polarized carbon - bond ea oksijene, 'me athomo ea carbon e le sebaka sa electrophilic. Tlhaselo ea ion ea cyanide e theha setlamo se secha sa carbon - cyanide, 'me athomo ea oksijene ea sehlopha sa carbonyl e fumana tefiso e mpe. Mohato o latelang, mohloli oa proton, joalo ka metsi kapa asiti, o hlahisa athomo ea oksijene ho etsa cyanohydrin. Boitšoaro bona bo ka khutlisetsoa morao, 'me tekano e ka fetoloa ho ea sehlahisoa ka ho laola maemo a karabelo.

Keketso ho Imines: Ka karabelo ea Strecker, ho eketsoa ha ion cyanide ho ion ionium, e entsoeng ho tloha karabelo ea aldehyde kapa ketone e nang le ammonia, e latela mokhoa o tšoanang oa ho eketsa nucleophilic. The Ionium ion e na le tefiso e ntle ho athomo ea naetrojene, e etsang hore athomo ea carbon e haufi le eona e be electrophilic. Ion ea cyanide e hlasela athomo ena ea carbon, e theha setlamo se secha sa carbon - cyanide 'me se etsa hore ho thehoe α - amino nitrile.

Mehopolo ea Ts'ireletso

Ho bohlokoa ho totobatsa hore sodium cyanide e chefo haholo. Ho e hema, ho e noa, kapa ho ama letlalo ka eona ho ka bolaea. Ha o sebetsa le sodium cyanide, ho tlameha ho lateloe liprothokholo tse tiileng tsa polokeho. Sena se kenyelletsa ho etsa liteko ka har'a mosi o kenang moea hantle, ho roala lisebelisoa tse nepahetseng tsa ts'ireletso joalo ka liatlana, likhalase le jase ea lab, le ho ba le meralo e nepahetseng ea ho arabela maemong a tšohanyetso haeba motho a ka pepeseha ka phoso.

fihlela qeto e

Sodium cyanide ke reagent e matla le e tenyetsehang ho organic synthesis. Bokhoni ba eona ba ho sebetsa joalo ka nucleophile le ho theha li-carbon bond tse ncha li e etsa sesebelisoa sa bohlokoa bakeng sa litsebi tsa k'hemistri ho kopanya mefuta e mengata ea metsoako ea manyolo. Ho utloisisa mekhoa ea karabelo e kenyelletsang sodium cyanide ho bohlokoa bakeng sa ho rala litsela tse sebetsang tsa maiketsetso le ho bolela esale pele liphetho tsa karabelo. Leha ho le joalo, ka lebaka la chefo e phahameng, tšebeliso ea eona e tlameha ho laoloa ka hloko le ho etsoa ka mehato e matla ea tšireletso ho sireletsa bophelo bo botle ba litsebi tsa lik'hemik'hale le tikoloho.