Homologous series

Nyob rau hauv Science News for KIDS, muaj ntau pawg ntawm cov organic tshuaj, yus muaj los ntawm zoo xws li cov zog thiab koom los ntawm cov general mis, uas qhia txog tus qauv ntawm lub yam ntxwv sib txawv ntawm txhua tus tom ntej neeg ntawm yav tas los pab pawg neeg. Piv txwv li, ib tug homologous series ntawm alkanes, alkenes, alkynes , los yog lwm yam pab pawg. Qhov no nomenclature yog ntawm kuj zoo kawg tseem ceeb rau txoj kev tshawb no los yog kev xyaum ntawm forecasting. Rau organic tshuaj hauv cov pab pawg, muaj kev hloov nyob rau hauv cov tshuaj thiab lub zog, thiab lawv muaj tag nrho ze rau nrog qhov kev hloov nyob rau hauv molecular ceeb thawj.

Attendance tseem ceeb yog cov kev cai uas piav qhia txog yuav ua li cas lub thaj chaw ntawm tshuaj nyob rau hauv txoj kev hloov los ntawm ib pab pawg neeg mus rau lwm. Yuav kom to taub li cas yog ib tug homologous series, yuav tsum xav txog tej piv txwv. Rau tej pab pawg neeg ntawm tebchaw yuav ua tus yam ntxwv kub ntawm melting (crystallization), boiling (hws) thiab ceev nrog ua molecular nyhav thiab tus xov tooj ntawm cov pa roj carbon atoms nyob rau hauv lub molecule.

Nyeem hydrocarbons yog hu ua paraffinic los yog nyeem; lawv sawv cev rau acyclic (tsis muaj mus) compound ncaj los yog branched lug, lub atoms nyob rau hauv lub lwg me me uas yog koom los ntawm ib bonds. Tag nrho cov mis yog CnH2n + 2 thiab qhia txog ib tug homologous series ntawm alkanes. Molecule txhua tom ntej neeg nce raws li muab piv nrog rau yav tas los ib tug C atom thiab ob atoms rau H. nyeem hydrocarbons muaj xws li:

• methane;
• ethane;
• hluav taws roj zeb, thiab hais txog.

Rau nyeem hydrocarbons kuj muaj xws li cycloparaffins. Qhov no yog ib tug loj pawg ntawm cov organic tebchaw uas nws molecules yog kaw rings. Homologous series ntawm lawv muaj cov mis CnH2n, pib nrog cov tshuaj rau peb cov pa roj carbon atoms. Piv txwv ntawm cycloparaffins:

• cyclopropane;
• cyclobutane;
• cyclopentane, etc.

Unsaturated los yog unsaturated hydrocarbons kuj acyclic. Cov no muaj xws tshuaj ntawm cov qub thiab iso-qauv. Homologous series ntawm alkenes muaj cov kev mis CnH2n. Cov tebchaw yog tsiag ntawv los ntawm xub ntiag ntawm ib tug muab ob npaug rau daim ntawv cog lus ntawm ob tug carbon atoms. Yog hais tias lub yav dhau los kab pib nrog ib tug hydrocarbon nrog ib tug carbon atom (methane), uas pib nrog tshuaj nyob rau hauv lub molecule uas muaj ob carbon atoms. Piv txwv ntawm alkenes:

• ethene;
• propyl;
• butene, thiab hais txog.

Hydrocarbons nyob rau hauv lub molecule ob carbon atoms kev cob cog rua ntawm triple daim ntawv cog lus muaj ntau unsaturated, txwv tsis pub xa mus rau raws li acetylene. Lawv koom siab los ntawm ib tug homologous series ntawm alkynes. Nws yog piav los ntawm cov mis CnH2n-2 thiab pib nrog acetylene nyob rau hauv cov mis uas yog ob atoms C. Piv txwv ntawm alkynes:

• ethyne;
• propyne;
• butyn-1 thiab thiaj li nyob.

Unsaturated acyclic hydrocarbons nyob rau hauv uas lub molecule muaj ob tug muab ob npaug rau bonds yog hu ua diene. Lawv muaj cov kev mis CnH2n-2. Lawv homologous series pib nrog ib tug hydrocarbon nrog peb carbon atoms nyob rau hauv lub molecule. Lub ob bonds yuav conjugated (sib cais los ntawm ib tug tib daim ntawv cog lus) cumulated (nyob rau ib sab atoms) los yog cais (sib cais ntau yam ib bonds). Piv txwv ntawm dienes:

• 1,2-propadiene;
• 1,3-butadiene;
• isoprene, etc.

Ib tug tshwj xeeb cov pab pawg neeg yog tsim los ntawm tshuaj cyclic qauv nyob rau hauv ib tug qauv uas muaj ib tug benzene nplhaib. Homologous series ntawm ib nrab uas muaj ntxhiab hydrocarbon pib nrog cov compound nrog rau cov pa roj carbon atoms - benzene. Homologues ntawm no series raug tsim los ntawm hloov ib los yog ntau tshaj hydrogen atoms sib raug zoo rau lub benzene nplhaib nyob rau hauv lub radicals. Yog li, ib tug xov tooj ntawm tej yam tshuaj: benzene, toluene, xylene. Yog hais tias lub molecule muaj ob los yog ntau tshaj substituents uas qhia hauv lub xub ntiag ntawm isomers ntawm cov tshuaj. Lwm yam homologous series ntawm aromatics yog tsim los ntawm naphthalene, anthracene, thiab lwm yam.

Yog hais tias lub hydrocarbon molecule muaj ib tug functional ib pawg, xws tshuaj kuj roos ib tug homologous series.

• Ob peb alcohols yus muaj nyob rau hauv ib tug molecule ib hydroxyl pab pawg neeg (-OH). Rau monoalcohols ib hydrogen atom nyob rau hauv ib tug acyclic hydrocarbon pawg los ntawm ib tug hydroxyl pab pawg neeg; mis: CnH2n + 1OH. Tseem muaj series ntawm polyols.
• Ob peb phenols tsiag ntawv los ntawm muaj nyob rau hauv lub molecule thiab ib tug hydroxyl pab pawg neeg (-OH), tab sis nws ntau xyoo hydrogen rau lub benzene nplhaib.
• Yus muaj los ntawm ib tug xov tooj ntawm aldehydes ib molecule ntawm cov tshuaj compound ntawm lub carbonyl pab pawg neeg (> C = O); aldehydes ntawm lub dav mis: R-CH = O.
• Ib tug xov tooj ntawm ketones kuj txawv los ntawm xub ntiag ntawm lub carbonyl pab pawg neeg (> C = O), tab sis yog hais tias nws yog kev cob cog rua nrog aldehydes ib tug tshaj dhau, ces tus ob ketones hydrocarbon radical. Ketones mis: R1-CO-R2.
• Ib tug xov tooj ntawm carboxylic acids txawv los ntawm lwm yam tshuaj carboxyl pab pawg neeg, combines lub carbonyl thiab hydroxyl pawg. Formula - RCOOH.

Rau txhua kab, seb puas homologous series aldehydes, carbonic (organic) acids, alcohols los yog lwm yam tshuaj, lawv lub zog yuav lom zem ntau yog nyob ntawm seb hom kev haumxeeb pab pawg neeg thiab ib txwm sib txawv nyob rau hauv xov tooj nrog ua molecular yuag tshuaj. Qhov no kev faib yog ib tug broad chav kawm ntawv ntawm cov tshuaj lub tebchaw pab kom to taub qhov xwm thiab kawm lawv lub zog.