Tauhohenga whakauru: whakaahuatanga, tauira whārite

oroko tokomaha tauhohenga whakauru te ara ki te faaineineraa o ngā pūhui he tono whaipainga. homai he wāhi nui i roto i te pūtaiao matū me te ahumahi te whakauru electrophilic me nucleophilic. I roto i te kōtuitanga organic, enei tukanga i te maha o ngā āhuatanga e kia tuhia.

He momo o ari matū. tauhohenga whakauru

huringa matū e pā ana ki te huringa o te mea, he maha o ngā āhuatanga rerekē. Kia hei putanga rerekē, ngā pānga waiariki; Kei te haere te tahi mau tukanga ki te whakaoti, mai te reira i roto i te tahi atu taurite matū. Whakakēngia āpiha Kei te maha haere tahi i te reira na roto i te whakanui ake i whakaiti i te tohu o te piti hāora ranei. I roto i te whakarōpū o tītohu matū i roto i o ratou hua whakamutunga utu whakarongo ki nga rerekētanga kounga, me te ine i waenga i te matū hohe i ngā hua. Ka taea e ēnei āhuatanga e taiea 7 momo o tauhohe matū, tae atu whakauru, e puta rite ki te kaupapa: A-B-C A + C + B. Ko te tuhi māmā o te piha haapiiraa katoa o te tītohu matū homai he whakaaro e roto i nga rauemi tīmatanga ko te "hoariri pera-ka karanga "substituent korakora i roto i te ngota kaiwhakahohe, katote rōpū mahi. He āhuatanga o te kukū, me te tauhohenga whakauru kakara waiwaro.

Ka taea e whakauru tauhohenga puta i roto i te puka o te utu-rua: A-B-C + E C + A-B-E. Kotahi momo - displacement, hei tauira, te parahi, te rino i te otinga o te parahi ngāwhā: CuSO ₄ + Fe = FeSO ₄ + Cu. Ka rite ki taea te "te whawhai" matūriki ngāue ngota, katote ranei rōpū mahi

whakauru Homolytic (tuwhena, SR)

A, no te he noa ki te āhuatanga rerekē i te huarahi o tuwhena rua whaturama kotuari irahiko ka tohaina proportionally i waenganui i te "whatiwhatinga" o te rāpoi ngota. Hanganga o Radicals free. Tenei stabilization matūriki iu e puta rite ki te hua o tauhohe muri. Hei tauira, i roto i te faaineineraa o te ewaro i te mewaro hua Radicals free wāhi i roto i te tauhohenga whakauru: CH ₄ CH ₃ • + • H; CH ₃ • + • CH ₃ → C2H5; H • + • H → H2. wāhinga here Homolytic i runga i te tikanga whakahaere o te whakauru he ulungāanga o ngā hopi, te tauhohenga ko te pūāhua mekameka. kia te ngota mewaro H kia ä whakakapi i te māota. Waihoki ki te tauhohe ki pūkeha, iodine engari he taea ki te whakakapi tika ngā hopi hauwai, tauhohe kaha rawa köwhai ki a ratou.

tikanga wāhinga here Heterolytic

A, no te te huarahi o te tauhohenga whakauru rere katote, kua tohaina kāore irahiko i roto i matūriki hou puta ake. toro te rua here o irahiko te huarahi katoa ki tetahi o te "whatiwhatinga", tino maha, ki te hoa kōrero, te taha i wāhikē kiato kino i roto i te rāpoi ngota poara. Na roto i te whakauru tauhohe ngā te tauhohe o te hanganga o te methyl waipiro CH ₃ OH. I roto i te brommetane rāpoi ngota CH3Br āputa he huru heterolytic, he pūmau nga matūriki i ako. Mewaro riro te tiaki pai, me te bromo - tōraro: CH ₃ Br → CH ₃ ^{+ +} Br ^-; NaOH → Na ^{+ +} OH ^-; CH ₃ ^{+ +} OH ^- → CH ₃ OH; Na ^{+ +} Br ^- ↔ NaBr.

Electrophiles me nucleophiles

Matūriki e hapa irahiko me taea manako ratou, kua karangatia e "electrophiles." He ngota waro herea ia ki kōnakonako i roto i waiwaihā enei. Nucleophiles i te kiato irahiko nui, he ratou "patunga" o te rua o irahiko ki te waihanga i tētahi here kotuari. E huakina e nucleophiles electrophiles, tarepa o irahiko nga utu kino taonga tauhohenga whakauru. e pā ana tēnei āhuatanga i te te kaupapa o te ngota atu matūriki ranei - mahue rōpū. Ko tētahi atu momo o te tauhohenga whakauru - te patu i te nucleophile electrophile. I te tahi taime uaua ki te wehewehe i waenganui i nga tukanga e rua, tuku ki te whakakapinga o tetahi ranei te tahi atu momo, no te mea he uaua ki te whakapūtā rite te mea ahua o te rāpoi ngota - tïpako, a nei - kaiwhakahohe. Ko te tikanga i roto i ngā take pēnei i, e whakaaro nga āhuatanga e whai ake nei:

• te āhua o te rōpū mahue;
• te tauhohenga o te nucleophile;
• te āhua o te whakarewa;
• te wahi alkyl o te hanganga.

whakauru Nucleophilic (SN)

kua i roto i te tukanga o te ngā i roto i te rāpoi ngota organic kua whakanui ake te vahiraa. I roto i te whārite o te tiaki pai kino ranei wāhanga tohua e te pukapuka o te tātai reta Kariki. Vahiraa kōrero homai he tohu o te āhua o tona whaturama me te whanonga heke mai o "whatiwhatinga" o te rāpoi ngota. Hei tauira, he ngota waro i roto i te iodomethane he tiaki pai te kanohi, he reira he pokapū electrophilic. E rata ana te reira i te dipole o te wai, te wahi te hāora he taikaha o irahiko. I roto i te tauhohenga o te electrophile ki te nucleophile i hanga te methanol: CH ₃ + ahau H ₂ E → CH ₃ OH + HI. tauhohenga whakauru nucleophilic tango te wahi ki te whai wāhitanga o te katote tōraro whakatupato muingota ranei he rua irahiko noa, e kore nei e whai wāhi i roto i te hanga o te here matū. whai wāhi mātātoa o te iodomethane i SN _2-tauhohenga tika ki tona maia ki te whawhai nucleophilic me te konutawa nekeneke.

whakauru Electrophilic (SE)

pea te muingota organic pokapū nucleophilic reira, āhuatanga nei i te te te taikaha o te irahiko kiato. tauhohe te reira ki te kore o utu kino kaiwhakahohe electrophilic. Taua matūriki he ngota he free muingota orbital ki wahi o mātotoru irahiko iti. Te konutai formate waro he tiaki "-", tali e ki te wahi pai o te dipole wai - hauwai: CH ₃ Na + H ₂ E → CH ₄ + NaOH. Ko te hua o tēnei tauhohenga, whakauru electrophilic - mewaro. A, no te taunekeneke tauhohe heterolytic oppositely whakatupato pokapū o rāpoi waro, homai nei ratou hunaonga ki a katote i roto i inorganic matū matū. e kore e e wareware te reira e te varavara haere tahi te faafariuraa o ngā pūhui matū waro e te hanganga o enei tīhiko me ng ngota.

Unimolecular me tauhohe bimolecular

Ko te whakauru nucleophilic he monomolecular (SN1). Na roto i tenei tikanga, he hua nui rere tauhohenga wai o te kōtuitanga organic - wānanga pūhaumāota butyl. He puhoi te wā tuatahi, kua whai pānga te reira ki te dissociation ahu whakamua ki carbonium te māraa, me te anion pūhaumāota. Ko te wāhanga tuarua ko puta he tauhohe tere katote, me te wai carbonium. Ko te whārite o te tauhohe o te whakauru o te kōnakonako i roto i te waiwaro tahi ki te whiwhi waipiro hydroxy me tuatahi: (CH _{3) 3} C-Cl → (CH _{3) 3} C ^{+ +} Cl ^-; (CH _{3) 3} C ^{+ +} H ₂ E → (CH _{3) 3} C-OH ⁺ H +. Hoki tetahi-taahiraa tauhohenga wai o halides alkyl tuatahi, me te tuarua āhuatanga e whakangaromanga tukutahi o te waro e tika ana ki te kōnakonako me te hanganga o te rua C-OH. Tenei tikanga nucleophilic bimolecular whakauru (SN2).

tikanga Heterolytic o whakauru

whakauru tikanga tā te whakawhitinga irahiko, te hanganga o complexes takawaenga. puta te tauhohenga atu tere, te māmā he reira hoki intermediates angamaheni mo ia. E mea pinepine te haere i te tukanga i roto i te maha o ngā tohutohu te wā kotahi. te tikanga whiwhi te painga te ara i roto i nei e whakamahia nga matūriki, tono i te whakapaunga iti rawa o te pūngao mo tona hanganga. Hei tauira, faarahi te aroaro o te here rua te tūponotanga o te māraa ļa allyl CH 2 = CH-CH ₂ ^+, whakaritea ki te _CH3 ⁺ katote. takoto te take i roto i te kiato irahiko o te here maha, e pä te delocalization o te tiaki pai, marara runga te rāpoi ngota katoa.

benzene tauhohenga whakauru

Ko te rōpū o ngā pūhui matū waro, e kua āhuatanga e whakauru electrophilic - arena. mowhiti Benzene - he ahanoa watea mō te whawhai electrophilic. haamata kōrero te tukanga ki te rua o nga kaiwhakahohe vahiraa, reira hanga kapua irahiko electrophile pātata te mowhiti benzene. Ko te hua ko te whakawhitinga matatini. Faufaa kōrero matūriki electrophilic ki tetahi o nga ngota waro kahore ano, e ngā reira ki te tiaki kino katoa "kakara ono" irahiko. I roto i te toru o taahiraa o te electrophile tukanga me kotahi ngota mowhiti waro herea te rua noa o irahiko (kotuari here). Otiia i roto i tenei take, ko te whakangaromanga o te "kakara ono", i te mea disadvantageous i roto i ngā o te kāwanatanga pūngao tauwhiro pūmau whakatutuki. He ko he āhuatanga e taea te huaina he "tuku o te iraoho." Kei te wahia te reira i atu H ^+, ora te pūnaha kōrero pūmau, arenes angamaheni. taonga te taha Kei roto hauwai te māraa o te mowhiti benzene me te anion i te rua o nga kaiwhakahohe.

Tauira o te tauhohenga whakauru o te matū waro

Hoki waiwaro tahi rawa angamaheni tauhohenga whakauru. Tauira o tauhohe electrophilic me nucleophilic taea arahi ki cycloalkanes me arenes. tauhohe rite ana i roto i te rāpoi ngota o ngā matū waro e raro tikanga noa, engari te nuinga o - me te i te whakawera i roto i te aroaro o kaiwhakakökï. Na roto i te tukanga noa, me te pai ako ngā whakakapinga kakara electrophilic. Ko te tauhohenga tino nui o tenei momo:

1. Nitration o benzene ki waikawa hauota i roto i te aroaro o te H ₂ SO ₄ - whai i te kaupapa: C ₆ H ₆ → C ₆ H ₅ -No _2.
2. Ko te kōnakonakotanga catalytic o benzene, rawa chlorination, i te whārite: C ₆ H ₆ + Cl ₂ → PF ₆ H ₅ Cl + HCl.
3. sulfonation kakara o puta benzene ki "horekau he" waikawa pungatara, kua hanga e waikawa benzenesulfonic.
4. Alkylation - whakakapinga o te ngota hauwai i te mowhiti benzene ki alkyl.
5. Acylation - te hanganga o ketones.
6. Formylation - whakakapi i te hauwai i runga i te rōpū cho me te hanganga o aldehydes.

Na roto i te whakauru tauhohe ngā te tauhohenga i roto i waiwaro tahi me cycloalkanes, te patu i ai nga kōnakonako wātea here C-H. kia Derivatization kia pā ana ki whakakapinga o tetahi, e rua katoa o te ngota hauwai i roto i waiwaro kukū me cycloparaffins ranei. E rave rahi o te galogenoalkanov o iti taimaha rāpoi e whakamahia i roto i te hanga o atu matū matatini no ki akomanga rerekē. Ko te angitu tutuki i roto i te ako o tikanga o tauhohenga whakauru, ka hoatu e te hiringa kaha ki te whanaketanga o whāiti i runga i te pūtake o ngā waiwaro, cyclo-wā, me te waiwaro halogenated.