Acetic acid yog ib qho ntawm cov txwv carboxylic acids. Raws li, lwm cov saturated carboxylic acids tuaj yeem yog homologues ntawm acetic acid. Lawv cov cuab yeej cuab tam yog muaj cov pab pawg carboxyl, uas tsuas yog txhais lawv li cov organic acids.
Lub tswvyim ntawm homology hauv chemistry
Nyob rau hauv cov organic chemistry, cov khoom ntawm ib qho kev sib xyaw feem ntau yog txiav txim los ntawm ib lossis ntau pawg ua haujlwm muaj nyob hauv nws. Yog li, piv txwv li, cov khoom ntawm cawv yog vim muaj cov pab pawg hydroxyl -OH, aldehydes thiab ketones - carbonyl pawg -CO. Cov pab pawg ua haujlwm tau txuas nrog rau cov pob txha pob txha ntawm cov molecule. Thiab txij li cov pa roj carbon muaj peev xwm (uas yog tag nrho cov organic chemistry yog raws) los tsim cov hlua ruaj khov ntawm cov atoms, tib pab pawg tuaj yeem txuas rau cov khoom sib txawv ntawm qhov sib txawv thiab cov khoom sib txuas uas zoo sib xws hauv cov khoom siv tshuaj, tab sis vim qhov sib txawv ntawm Qhov loj thiab qhov ntau, cov pa roj carbon atom yog qhov sib txawv. Cov txheej txheem kev sib txuastxawv ib leeg los ntawm ib pab pawg -CH2-, hu ua homological series, pawg nws tus kheej -CH2- hu ua qhov sib txawv homological, thiab cov tebchaw hauv kab - homologues. Qhov piv txwv yooj yim tshaj plaws ntawm homologous series yog series ntawm saturated hydrocarbons (alkanes).
Siv cov lej lej qis, nws yooj yim los txheeb xyuas tias ob qho ntawm cov ntsiab lus no txawv ntawm ib leeg los ntawm nCH2 pawg.
Nws tseem ceeb heev uas yuav tsum tau xyuam xim rau thawj zaug, uas yog, cov tswv cuab yooj yim ntawm homologous series. Nyob rau hauv cov ntaub ntawv ntawm alkanes, qhov no yog methane: nws tsuas muaj ib tug carbon atom thiab muaj tag nrho cov yooj yim zog ntawm alkanes. Txawm li cas los xij, qee zaum carbon ib leeg tsis txaus. Piv txwv li, nyob rau hauv lub series ntawm alkenes, qhov yooj yim compound yog ethene (uas, los ntawm analogy nrog ethane, muaj ob carbons), los tsim ib tug carbon-carbon ob daim ntawv cog lus tus yam ntxwv ntawm alkenes, tsawg kawg yog ob atoms C.
Homologous series ntawm saturated carboxylic acids
Ethanoic (ib lub npe - acetic) acid belongs rau chav kawm ntawm kev txwv cov carboxylic acids. Nws cov khoom raug txiav txim los ntawm pawg ua haujlwm -COOH, tseem hu ua carboxyl.
Cov mis mos molecular ntawm acetic acid yog CH3COOH, los yog C2H4 O 2. Koj tuaj yeem ntxiv daim tshiab -CH2- rau nws kom tau txais cov molecules loj: homologues ntawm acetic acid nrog cov saw hlau ntawm peb, plaub, kaum thiab txawm peb caug atoms ntev. Txawm li cas los xij, nyob rau hauv cov ntaub ntawv no, nws kuj tseem tuaj yeem "tiav" ib qho kev sib txuas ntawm acetic acid:ces peb tau methane, los yog acetic acid HCOOH. Txawm hais tias qhov tseeb tias cov pa roj carbon monoxide tsuas yog nyob rau hauv pab pawg ua haujlwm, formic acid kuj yog nyob rau hauv chav kawm ntawm carboxylic acids thiab yog qhov yooj yim tshaj plaws ntawm lawv cov homologous series.
Hloov cov khoom hauv homologous series
Cov homologues ze tshaj ntawm acetic acid yog methane acid HCOOH thiab propanoic (los yog propionic) acid C2H5COOH. Tag nrho peb lub tebchaw yog cov kua dej nyob rau hauv ib txwm muaj, methane thiab ethanoic acids yog volatile, nrog ib tug pungent tsw. Txwv tsis pub carboxylic acids nrog cov roj carbon ntev ntawm 4 txog 24 atoms yog cov hu ua saturated fatty acids cais los ntawm cov roj thiab cov rog. Kuj tseem muaj cov kua qaub loj dua - lawv, raws li txoj cai, yog ib feem ntawm waxes lossis rog ntawm cov tsiaj keeb kwm. Cov carboxylic acids siab dua yog cov khoom khov.
