Cov Kev Tshwm Sim Tshwj Xeeb ntawm Cov Pab Pawg Ua Haujlwm
Cov tshuaj tiv thaiv yog lub plawv ntawm chemistry, thiab cov pab pawg ua haujlwm yog cov feem ntawm cov molecule uas nyob hauv nruab nrab ntawm kev ua haujlwm tshuaj. Txhua pab pawg ua haujlwm muaj nws tus kheej reactivity thiab cov yam ntxwv, ua rau muaj ntau hom kev hloov pauv tshuaj. Kev nkag siab txog cov tshuaj tiv thaiv tshwj xeeb ntawm cov pab pawg ua haujlwm yog qhov tseem ceeb rau kev tswj hwm thiab tsim cov molecule hauv ntau qhov chaw, los ntawm cov tshuaj mus rau cov khoom siv thev naus laus zis.
Cov Pab Pawg Ua Haujlwm: Kev Txhais thiab Qhov Tseem Ceeb
Ib pawg ua haujlwm yog ib pawg ntawm cov atoms hauv ib lub molecule uas ua haujlwm ua ib chav reactive thiab txiav txim siab cov khoom siv tshuaj lom neeg ntawm lub molecule. Piv txwv li ntawm cov pawg ua haujlwm suav nrog hydroxyl (-OH), carbonyl (C=O), carboxyl (-COOH), amino (-NH2), thiab ether (-COC). Txhua pawg ua haujlwm muaj cov khoom siv reactive tshwj xeeb uas tso cai rau cov tshuaj lom neeg tshwj xeeb tshwm sim.
Cov Kev Tshwm Sim Tshwj Xeeb ntawm Cov Pab Pawg Ua Haujlwm
1. Pawg Hydroxyl (-OH)
Cov pab pawg Hydroxyl muaj nyob rau hauv cov cawv thiab phenols, thiab lawv ua rau muaj ntau yam kev tshuaj lom neeg tshwj xeeb.
Kev Ua Haujlwm Oxidation
Cov cawv tuaj yeem raug oxidized los tsim cov aldehydes, ketones, thiab carboxylic acids. Kev oxidation thawj zaug ntawm cov cawv tsim cov aldehydes, uas tom qab ntawd raug oxidized rau carboxylic acids. Cov cawv thib ob raug oxidized rau ketones.
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R-CH2OH + [O] → R-CHO + [O] → R-COOH
R-CHOH-R' + [O] → R-CO-R'
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Kev Ua Kom Qhuav
Kev qhuav dej ntawm cov cawv tuaj yeem tsim cov alkenes thiab ethers. Thaum muaj cov kua qaub muaj zog xws li H2SO4, cov cawv dhau los ua kev qhuav dej hauv cov alkenes lossis kev qhuav dej hauv cov ethers.
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R-CH2-CH2OH → R-CH=CH2 + H2O (kev qhuav dej hauv lub molecule)
2 R-OH → ROR + H2O (kev qhuav dej ntawm cov molecule)
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2. Pawg Carbonyl (C = O)
Cov pawg carbonyl pom muaj nyob rau hauv aldehydes, ketones, thiab carboxylic compounds. Lawv cov tshuaj tiv thaiv suav nrog nucleophilic addition, reduction, thiab condensation.
Kev Ntxiv Nucleophilic
Cov pa roj carbon hauv pawg carbonyl yog electrophilic thiab tuaj yeem raug tawm tsam los ntawm nucleophile los tsim cov cawv.
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R-CO-R' + NuH → RC(OH)(Nu)-R'
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Kev txo qis
Aldehydes thiab ketones tuaj yeem raug txo kom ua cawv los ntawm kev txo cov neeg sawv cev xws li NaBH4 lossis LiAlH4.
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R-CHO + 2[H] → R-CH2OH
R-CO-R' + 2[H] → R-CHOH-R'
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Aldol Condensation Reaction
Aldol condensation muaj ob lub aldehyde lossis ketone molecules uas tsim cov β-hydroxy aldehyde lossis ketone thiab tuaj yeem dhau los ua dehydration los tsim cov enone.
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2 R-CHO → R-CH(OH)-CH(R)-CHO
R-CHOH-CH(R)-CHO → R-CH=CH(R)-CHO + H2O
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3. Carboxyl Group (-COOH)
Carboxylic acids ua rau muaj kev cuam tshuam xws li deprotonation, esterification, thiab txo qis.
Kev Ua Haujlwm Deprotonation
Cov carboxylic acids (R-COOH) tuaj yeem poob cov protons los ua cov carboxylates (R-COO⁻).
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R-COOH → R-COO⁻ + H⁺
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Kev Ua Haujlwm Esterification
Cov carboxylic acids react nrog alcohols los tsim cov esters thiab dej hauv Fischer esterification reaction.
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R-COOH + R'OH → R-COO-R' + H2O
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Kev txo qis
Carboxylic acids tuaj yeem txo kom ua cawv siv cov neeg sawv cev txo qis muaj zog xws li LiAlH4.
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R-COOH + 4[H] → R-CH2OH + H2O
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4. Pawg Amino (-NH2)
Cov pawg amino muaj nyob rau hauv amines thiab ua rau muaj kev cuam tshuam alkylation, acylation, thiab nitrosation.
Cov tshuaj tiv thaiv Alkylation thiab Acylation
Cov amines yog tsim los ntawm alkylation ntawm alkyl halides nrog ammonia lossis amines. Amines kuj tseem tuaj yeem cuam tshuam nrog acyl halides lossis anhydrides los tsim cov amides.
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RX + NH3 → R-NH2 + HX
R-NH2 + R'-COCl → R-NH-CO-R' + HCl
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Kev Ua Haujlwm Nitrosation
Cov amines thawj zaug thiab theem nrab tuaj yeem dhau los ntawm cov tshuaj nitrosation nrog nitrous acid los tsim cov ntsev diazonium rau cov amines thawj zaug lossis N-nitrose amines rau cov amines theem nrab.
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R-NH2 + HONO → R-N2⁺ + H2O (ntses diazonium)
R2NH + HONO → R2N-N = O + H2O (N-nitroso amine)
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5. Pawg Ether (COC)
Cov ethers ua haujlwm txawv ntawm cov cawv vim tias lawv tsis muaj cov protons uas yooj yim tso tawm.
Kev Sib Tsoo Acid
Cov ethers tuaj yeem raug cleaved los ntawm cov kua qaub muaj zog los tsim cov cawv thiab alkyl halides.
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RO-R' + HBr → R-OH + R'-Br
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Kev Ua Pa Tawm ntawm Huab Cua Autoxide
Cov ethers tuaj yeem raug oxidized los ntawm huab cua los tsim cov ether peroxides tawg.
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2 RO-R' + O2 → 2 RO-R'-O-OH
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Xaus
Kev nkag siab zoo txog cov tshuaj tiv thaiv tshwj xeeb ntawm cov pab pawg ua haujlwm hauv cov tshuaj lom neeg yog qhov tseem ceeb rau ntau yam kev siv. Cov pab pawg ua haujlwm txiav txim siab txog cov khoom siv tshuaj lom neeg thiab kev ua haujlwm ntawm cov molecules, ua rau muaj ntau yam kev hloov pauv tshuaj lom neeg tseem ceeb hauv cov tshuaj organic, bioorganic, thiab cov khoom siv tshuaj lom neeg. Los ntawm kev siv cov kev paub no, cov kws tshuaj lom neeg tuaj yeem tsim thiab tsim cov molecules tshiab nrog kev siv dav hauv kev kho mob, thev naus laus zis, thiab ntau ntxiv.
