Iqhaza kanye Nezinqubo ze-Sodium Cyanide ku-Organic Synthesis

Isingeniso

I-Sodium Cyanide (NaCN), i-crystalline eqinile emhlophe encibilika kakhulu emanzini, iyisisekelo esiqinile kanye ne-nucleophile enamandla, okwenza ibe yi-reagent ebalulekile ekuhlanganisweni kwe-Organic . Naphezu kobuthi bayo obukhulu, okudinga izinyathelo zokuphepha eziqinile ngesikhathi sokuphathwa, i-Sodium cyanide idlala indima ebalulekile ekuhlanganisweni kwamakhemikhali ahlukahlukene e-organic, okuhlanganisa imithi, amakhemikhali ezolimo, kanye nama-polymer.

Indima ye-Sodium Cyanide ku-Organic Synthesis

I-Cyanide Ion njenge-Nucleophile

I- ion ye-cyanide ngaphakathi kwe -Sodium Cyanide iyi-nucleophile esabela kakhulu. Ngenxa yokushaja okungekuhle ku- athomu ye-Carbon kanye ne-electronegativity ephezulu ye-athomu ye-nitrogen, ingahlasela izikhungo ze-electrophilic kuma-molecule e-organic, njengeqembu le-carbonyl, ama-alkyl halides, nama-epoxide.

Ukwakhiwa kwamabhondi e-C - C

Omunye wemisebenzi ebaluleke kakhulu ye -sodium cyanide ekwakhiweni kwezinto eziphilayo ukudalwa kwezibopho ezintsha ze-carbon-carbon, ezitholakala ngokushintshaniswa kwe-nucleophilic kanye nokusabela kokwengeza. Isibonelo, lapho i-alkyl halide isabela ne-sodium cyanide, i-cyanide ion ithatha indawo ye-halide ion, okuholela ekwakhekeni kwe-nitrile. Lokhu kusabela kunikeza indlela elula yokungenisa i-athomu yekhabhoni eyengeziwe ku-molecule. Ngemva kwalokho, iqembu le-nitrile lingaguqulwa libe amanye amaqembu asebenzayo njenge-carboxylic acid, ama-amine, noma ama-aldehydes ngezinqubo ezahlukahlukene zamakhemikhali.

Ukuhlanganiswa kwe-Amino Acids - Ukusabela kwe-Strecker

I-sodium cyanide iyingxenye eyinhloko ekuphenduleni kwe-Strecker, esetshenziselwa ukuhlanganiswa kwe-α - amino acid. Kule ndlela yokusabela, i-aldehyde noma i-ketone ihlangana ne-ammonium chloride ne-sodium cyanide ukwenza i-α - amino nitrile. Le α - amino nitrile ingabese igaywa nge-hydrolyzed ukuze ikhiqize i-α - amino acid ehambisanayo.

Ukusabela kuvela ngezinyathelo ezimbalwa: Okokuqala, iqembu le-carbonyl le-aldehyde noma i-ketone lidlula i-protonation, okwandisa i-electrophilicity yalo. Khona-ke, i-molecule ye-ammonia ihlasela iqembu le-protonated carbonyl, elandelwa ukuchithwa kwe-deprotonation ukuze yakhe i-hemiaminal. Okulandelayo, iqembu le-hydroxyl le-hemiaminal likhishwa nge-protonated, okuholela ekuqedweni kwamanzi kanye nokwakheka kwe- an ioni ye- an hemia. I-cyanide ion ibese ihlasela i-ganium ion ukuze ikhiqize i-α - amino nitrile. Ekugcineni, i-hydrolysis ye-α - amino nitrile phambi kwe-asidi noma isisekelo inikeza i-α - amino acid.

I-synthesis of Nitriles evela ku-Aryl Halides - I-Rosenmund - von Braun Reaction

Ekuphenduleni kwe-Rosenmund - von Braun, i-sodium cyanide isetshenziselwa ukuguqula i-aryl halides, okungama-halogen - ama-compounds anuka kamnandi, abe yi-aryl nitriles. Icutshungulwa yi-copper(I) cyanide futhi ngokuvamile idinga amazinga okushisa aphezulu, lokhu kusabela kuhilela ukwakheka kwe-copper - aryl intermediate. I-cyanide ion evela ku-sodium cyanide bese isabela nalokhu okuphakathi ukuze yakhe i-aryl nitrile. Le nqubo ibalulekile ekwethuleni iqembu elisebenzayo le-nitrile eringini enephunga elimnandi, elingase liphinde lilungiswe ukuze kuhlanganiswe izinhlanganisela ezihlukahlukene ezinuka kamnandi, ezifana nemithi kanye nodayi.

Ukuhlanganiswa Kwezinhlanganisela zeCarbonyl

I-sodium cyanide nayo ibamba iqhaza ekuhlanganiseni ama-carbonyl compounds. Isibonelo, uma isabela nge-epoxide, i-ion ye-cyanide ihlasela i-athomu yekhabhoni efakwe endaweni encane yeringi ye-epoxide, okubangele ukuthi indandatho ivuleke. I-hydrolysis elandelayo ye-cyanohydrin ewumphumela ingaholela ekwakhekeni kwe-carbonyl compound.

Izindlela Zokusabela Ezibandakanya I-Sodium Cyanide

I-Nucleophilic Substitution Reactions

Indlela ye-SN2 : Lapho i-sodium cyanide isabela nama-alkyl halide ayinhloko, ukusabela kuvame ukulandela indlela ye-SN2 (i-bimolecular nucleophilic substitution). I-cyanide ion ihlasela i-athomu yekhabhoni exhunywe kwi-halogen kusukela ngemuva, okuphambene nendawo ye-ion ye-halide eshiyayo. Lokhu kuyimpendulo ehlangene lapho ukuphuka kwesibopho sekhabhoni-halogen kanye nokwakheka kwesibopho sekhabhoni-cyanide kwenzeka ngasikhathi sinye. Izinga lokusabela lincike ekugxilweni kokubili kwe-alkyl halide kanye ne-ion ye-cyanide, kanye ne-stereochemistry yomkhiqizo iguquliwe uma kuqhathaniswa neyokuqala.

Indlela ye-SN1 : Nge-tertiary alkyl halides, ukusabela kungaqhubeka ngendlela ye-SN1 (unimolecular nucleophilic substitution). Okokuqala, i-alkyl halide iyahlukana ukuze yakhe i-carbocation intermediate. Ngemuva kwalokho, i-cyanide ion ihlasela le carbocation ukuze yakhe umkhiqizo. Indlela ye-SN1 ibonakala ngokwakhiwa kwe-planar carbocation intermediate, futhi umkhiqizo ungabonisa ingxube ye-stereochemistries, into eyaziwa ngokuthi i-racemization, ngenxa ye-nucleophile ehlasela kuzo zombili izinhlangothi ze-planar carbocation.

I-Nucleophilic Addition Reactions

Ukwengezwa Kwamaqembu E-Carbonyl : Lapho i-sodium cyanide isabela nama-aldehydes noma ama-ketone, i-cyanide ion ihlasela i-athomu ye-carbonyl carbon ephilic. Iqembu le-carbonyl linesibopho se-carbon-oxygen esihlanganisiwe, lapho i-athomu ye-carbon iyisayithi le-electrophilic. Ukuhlaselwa kwe-ion ye-cyanide kudala isibopho esisha se-carbon-cyanide, futhi i-athomu ye-oxygen yeqembu le-carbonyl ithola ishaja engemihle. Esinyathelweni esilandelayo, umthombo we-proton, njengamanzi noma i-asidi, uphrothotha i-athomu ye-oxygen ukuze yakhe i-cyanohydrin. Lokhu kusabela kuyaguqulwa, futhi ukulingana kungalungiswa kumkhiqizo ngokulawula izimo zokusabela.

Ukwengezwa kuma-Imines : Ku-Strecker reaction, ukwengezwa kwe-cyanide ion ku-iminium ion, eyakhiwa ngenxa yokusabela kwe-aldehyde noma i-ketone ene-ammonia, kulandela indlela efanayo yokwengeza i-nucleophilic. I-iminium ion ineshaja enhle ku-athomu ye-nitrogen, okwenza i-athomu yekhabhoni eseduze ibe yi-electrophilic. I-cyanide ion ihlasela le athomu yekhabhoni, yakha isibopho esisha sekhabhoni-cyanide futhi kuholele ekwakhekeni kwe-α-amino nitrile.

Ukucatshangelwa Kwezokuphepha

Kubalulekile ukugcizelela ukuthi i-sodium cyanide inobuthi kakhulu. Ukuhogela, ukuwungenisa, noma ukuthintana nawo esikhumbeni kungabulala. Lapho usebenza ne-sodium cyanide, izimiso zokuphepha eziqinile kufanele zilandelwe. Lokhu kuhlanganisa ukwenza izivivinyo endaweni engenisa umoya kahle, ukugqoka izinto zokuzivikela ezifanele njengamagilavu, izibuko, nejazi laselabhu, kanye nokuba nezinhlelo ezifanele zokusabela ezimweni eziphuthumayo uma kwenzeka uchayeka ngengozi.

Isiphetho

I-sodium cyanide iyi-reagent enamandla futhi eguquguqukayo ku-organic synthesis. Ikhono layo lokusebenza njenge-nucleophile futhi lidale amabhondi ekhabhoni amasha alenza libe yithuluzi elibaluleke kakhulu kosokhemisi ekuhlanganiseni inhlanganisela ebanzi yezinto eziphilayo. Ukuqonda izindlela zokusabela ezibandakanya i-sodium cyanide kubalulekile ekuklameni imizila yokwenziwa ephumelelayo nokubikezela imiphumela yokusabela. Kodwa-ke, ngenxa yobuthi bayo obuphezulu, ukusetshenziswa kwayo kufanele kulawulwe ngokucophelela futhi kwenziwe ngezinyathelo zokuphepha ezisezingeni eliphezulu ukuze kuvikelwe inhlalakahle yosokhemisi nemvelo.