Nws yuav muaj txiaj ntsig los pib nrog lub ntsiab lus ntawm alkanes. Cov no yog saturated los yog saturated hydrocarbons, paraffins. Koj tuaj yeem hais tias cov no yog cov carbons uas qhov kev sib txuas ntawm C atoms yog ua los ntawm cov ntawv cog lus yooj yim. Cov mis mos yog: CnH₂n+ 2.
Nws paub tias qhov piv ntawm tus lej ntawm H thiab C atoms hauv lawv cov molecules yog qhov siab tshaj plaws thaum piv nrog lwm cov chav kawm. Vim lub fact tias tag nrho cov valences nyob los ntawm C lossis H, cov khoom siv tshuaj lom neeg ntawm alkanes tsis qhia meej txaus, yog li ntawd, lawv lub npe thib ob yog cov kab lus saturated lossis saturated hydrocarbons.
Tseem muaj lub npe laus uas zoo tshaj plaws qhia txog lawv cov txheeb ze tshuaj inertness - paraffins, uas txhais tau tias "tsis muaj kev sib raug zoo" hauv kev txhais lus.
Yog li, lub ntsiab lus ntawm peb cov kev sib tham niaj hnub no: "Alkanes: homologous series, nomenclature, qauv, isomerism." Cov ntaub ntawv hais txog lawv lub cev lub cev yuav raug nthuav tawm.
Alkanes: qauv, nomenclature
Nyob hauv lawv, C atoms nyob hauv lub xeev xws li sp3-hybridization. Hais txogib qho alkane molecule tuaj yeem pom tau tias yog cov txheej txheem C tetrahedral uas txuas tsis tau rau ib leeg, tab sis kuj rau H.
Muaj zog, tsawg-polarity s-bonds ntawm C thiab H atoms. Atoms, ntawm qhov tod tes, ib txwm tig ib ncig ntawm daim ntawv cog lus yooj yim, uas yog vim li cas alkane molecules coj mus rau ntau hom, thiab daim ntawv cog lus ntev thiab lub kaum sab xis ntawm lawv yog qhov tseem ceeb. Cov ntaub ntawv uas hloov mus rau ib leeg vim kev sib hloov ntawm cov molecule nyob ib ncig ntawm σ-bonds yog hu ua nws conformations.
Nyob rau hauv tus txheej txheem ntawm detachment ntawm H atom los ntawm lub molecule nyob rau hauv kev txiav txim, 1-valent hais yog tsim, hu ua hydrocarbon radicals. Lawv tshwm sim los ntawm cov tebchaw ntawm tsis tsuas yog cov organic tshuaj, tab sis kuj inorganic sawv daws yuav. Yog tias koj rho tawm 2 hydrogen atoms los ntawm saturated hydrocarbon molecule, koj tau txais 2-valent radicals.
Yog li, lub npe ntawm alkanes tuaj yeem yog:
- radial (laus version);
- hloov pauv (thoob ntiaj teb, systematic). Nws tau thov los ntawm IUPAC.
Ntawm ntawm radial nomenclature
Hauv thawj kis, lub npe ntawm alkanes yog tus cwj pwm los ntawm cov hauv qab no:
- Kev txiav txim siab ntawm hydrocarbons raws li cov txiaj ntsig ntawm methane, uas 1 lossis ntau dua H atoms raug hloov los ntawm cov radicals.
- High degree ntawm kev yooj yim nyob rau hauv cov ntaub ntawv ntawm tsis heev sib txuas.
Txoj kev hloov pauv nomenclature
Qhov hloov pauv nomenclature ntawm alkanes muajcov yam ntxwv hauv qab no:
- Lub hauv paus rau lub npe yog 1 cov saw hlau, cov seem ntawm cov khoom tawg yog suav tias yog cov hloov pauv.
- Yog tias muaj ob peb qhov zoo tib yam radicals, tus lej raug qhia ua ntej lawv lub npe (tseem ceeb ntawm cov lus), thiab cov lej radical raug cais los ntawm commas.
Chemistry: alkane nomenclature
Rau qhov yooj yim, cov ntaub ntawv tau nthuav tawm hauv daim ntawv ntawm lub rooj.
| Npe khoom | Basic name (root) | Molecular formula | Lub npe ntawm cov pa roj carbon hloov pauv | Carbon substituent formula |
| Methane | Met- | CH₄ | Methyl | CH₃ |
| Ethan | T- | C₂H₆ | Ethyl | C₂H₅ |
| Propane | Prop- | C₃H₈ | Txhob | C₃H₇ |
| Bhutan | Tab sis- | C₄H₁₀ | Butyl | C₄H₉ |
| Pentane | Pent- | C₅H₁₂ | Pentyl | C₅H₁₁ |
| Hexane | Hex- | C₆H₁₄ | Gexyl | C₆H₁₃ |
| Heptane | Hept- | C₇H₁₆ | Heptyl | C₇H₁₅ |
| Octane | Oct- | C₈H₁₈ | Octyl | C₈H₁₇ |
| Nonan | Non- | C₉H₂₀ | Nonil | C₉H₁₉ |
| Dean | Dec- | C₁₀H₂₂ | Decil | C₁₀H₂₁ |
Cov npe saum toj no ntawm alkanes suav nrog cov npe uas tau tsim keeb kwm (thawj 4 tus tswv cuab ntawm koob ntawm cov hydrocarbons saturated).
Cov npe ntawm unfolded alkanes nrog 5 los yog ntau tshaj C atoms yog muab los ntawm Greek cov lej uas qhia txog tus naj npawb ntawm C atoms. Yog li, cov lus tom qab -an qhia tias cov khoom yog los ntawm cov khoom sib xyaw ua ke.
Thaum naming unfolded alkanes, ib qho uas muaj ntau tshaj plaws ntawm C atoms yog xaiv raws li cov saw tseem ceeb. Nyob rau hauv cov ntaub ntawv ntawm ob los yog ntau tshaj chains ntawm tib ntev, lub ntsiab saw yog ib tug uas muaj coob tus neeg hloov.
Alkanes isomerism
Methane CH₄ ua raws li hydrocarbon-yeej yawg koob ntawm lawv cov koob. Nrog rau txhua tus neeg sawv cev tom ntej ntawm methane series, muaj qhov sib txawv ntawm yav dhau los hauv pawg methylene - CH₂. Cov qauv notraceable thoob plaws hauv alkane series.
Tus kws tshawb fawb German Schiel tau tshaj tawm tsab ntawv thov hu rau qhov koob no homological. Txhais los ntawm Greek txhais tau tias "zoo ib yam, zoo ib yam."
Yog li, homologous series yog cov txheej txheem ntawm cov organic sib txuas uas muaj tib hom qauv nrog cov tshuaj zoo sib xws. Homologues yog cov tswv cuab ntawm ib qho kev muab. Qhov sib txawv ntawm homologous yog pawg methylene uas 2 qhov sib txawv ntawm qhov sib txawv.
Raws li tau hais ua ntej, qhov muaj pes tsawg leeg ntawm ib qho saturated hydrocarbon tuaj yeem qhia tau siv cov qauv dav dav CnH₂n + 2. Yog li, cov tswv cuab tom ntej ntawm homologous series tom qab methane yog ethane - C₂H₆. Txhawm rau txiav nws cov qauv los ntawm methane, nws yuav tsum tau hloov 1 H atom nrog CH₃ (daim duab hauv qab no).
Tus qauv ntawm txhua homologue ua tiav tuaj yeem muab los ntawm yav dhau los ib yam nkaus. Yog li ntawd, propane yog tsim los ntawm ethane - C₃H₈.
isomers yog dab tsi?
Cov no yog cov khoom uas muaj qhov zoo ib yam thiab muaj pes tsawg molecular muaj pes tsawg leeg (zoo tib yam molecular mis), tab sis cov qauv tshuaj sib txawv, thiab kuj muaj cov tshuaj sib txawv.
Cov hydrocarbons saum toj no txawv hauv qhov ntsuas qhov ntsuas kub: -0.5 ° - butane, -10 ° - isobutane. Hom isomerism no yog hu ua carbon skeleton isomerism, nws belongs rau hom qauv.
Tus naj npawb ntawm cov qauv isomers loj hlob sai nrog qhov nce ntawm cov pa roj carbon atoms. Yog li, C₁₀H₂₂ yuav sib haum mus rau 75 isomers (tsis suav nrogspatial), thiab rau C₁₅H₃₂ 4347 isomers twb paub lawm, rau C₂₀H₄₂ - 366 319.
Yog li, nws twb tau paub meej tias dab tsi alkanes, homologous series, isomerism, nomenclature yog. Tam sim no nws yog lub sijhawm txav mus rau IUPAC naming conventions.
IUPAC Nomenclature: Naming Rules
Ua ntej, nws yog qhov yuav tsum tau nrhiav hauv cov qauv hydrocarbon cov saw hlau uas ntev tshaj plaws thiab muaj cov khoom siv ntau tshaj plaws. Tom qab ntawd koj yuav tsum suav tus C atoms ntawm cov saw, pib los ntawm qhov kawg mus rau qhov kev hloov pauv ze tshaj plaws.
Secondly, lub hauv paus yog lub npe ntawm ib tug ncaj saw saturated hydrocarbon, uas sib haum mus rau lub ntsiab tseem ceeb tshaj plaws saw los ntawm tus naj npawb ntawm C atoms.
Thib peb, nws yuav tsum tau qhia cov lej ntawm cov chaw nyob ze uas cov neeg hloov pauv tau nyob ua ntej lub hauv paus. Lawv ua raws li cov npe ntawm cov neeg hloov pauv nrog ib tus hyphen.
Plaub, yog tias muaj cov khoom sib txawv ntawm C atoms sib txawv, cov chaw nyob sib xyaw ua ke, thiab cov lus qhia ua ntej tshwm sim ua ntej lub npe: di - rau ob tus neeg sib txawv, peb - rau peb, tetra - plaub, penta - rau tsib thiab lwm yam. Cov lej yuav tsum tau muab cais tawm ntawm ib leeg los ntawm tus lej cim, thiab los ntawm cov lus los ntawm hyphen.
Yog tib lub C atom muaj ob qhov hloov pauv ib zaug, tus locant kuj tau sau ob zaug.
Raws li cov cai no, lub npe thoob ntiaj teb nomenclature ntawm alkanes yog tsim.
Newman projections
Tus kws tshawb fawb Asmeskas nonpaj rau kev ua qauv qhia graphical ntawm conformations tshwj xeeb projection qauv - Newman projections. Lawv sib haum rau cov ntawv A thiab B thiab muaj nyob rau hauv daim duab hauv qab no.
Hauv thawj kis, qhov no yog A-shielded conformation, thiab thib ob, nws yog B-inhibited. Hauv txoj haujlwm A, H atoms nyob ntawm qhov tsawg kawg nkaus ntawm ib leeg. Daim ntawv no sib raug rau tus nqi loj tshaj plaws ntawm lub zog, vim lub fact tias cov repulsion ntawm lawv yog qhov loj tshaj plaws. Qhov no yog lub xeev tsis txaus siab, vim tias cov molecule nyhav tawm ntawm nws thiab txav mus rau qhov chaw ruaj khov B. Ntawm no, H atoms nyob deb li deb tau. Yog li, lub zog sib txawv ntawm cov haujlwm no yog 12 kJ / mol, vim tias qhov kev sib hloov dawb nyob ib puag ncig ntawm axis hauv ethane molecule, uas txuas cov methyl pawg, tsis sib xws. Tom qab nkag mus rau hauv txoj haujlwm muaj txiaj ntsig zoo, cov molecule nyob rau ntawd, hauv lwm lo lus, "slows". Yog vim li cas nws thiaj li hu ua inhibited. Qhov tshwm sim - 10 txhiab molecules ntawm ethane nyob rau hauv ib tug hindered daim ntawv ntawm conformation ntawm chav tsev kub. Tsuas yog ib leeg muaj qhov sib txawv - tsis pom tseeb.
Tau txais saturated hydrocarbons
Nws twb paub los ntawm tsab xov xwm tias cov no yog alkanes (lawv cov qauv, nomenclature tau piav qhia ntxaws ua ntej). Nws yuav muaj txiaj ntsig los xav txog yuav ua li cas kom tau lawv. Lawv raug tso tawm los ntawm tej yam ntuj tso xws li roj, natural gas, txuam gases, thiab thee. Cov txheej txheem hluavtaws kuj tseem siv tau. Piv txwv li, H₂ 2H₂:
- txheej txheem ntawm hydrogenation ntawm unsaturated hydrocarbons:CnH₂n (alkenes) → CnH₂n + 2 (alkanes)← CnH₂n-2 (alkynes).
- Los ntawm kev sib xyaw ntawm monoxide C thiab H - synthesis gas: nCO + (2n + 1)H₂ → CnH₂n + 2 + nH₂O.
- Los ntawm carboxylic acids (lawv cov ntsev): electrolysis ntawm anode, ntawm cathode:
- Kolbe electrolysis: 2RCOONa+2H₂O →R-R+2CO₂+H₂+2NaOH;
- Dumas cov tshuaj tiv thaiv (alkali alloy): CH₃COONa + NaOH (t) → CH₄ + Na₂CO₃.
- Oil cracking: CnH₂n+2 (450-700°) → CmH₂m+2+ Cn-mH₂(n-m).
- Gasification ntawm roj (khoom): C + 2H₂→CH₄.
- Synthesis ntawm complex alkanes (halogen derivatives) uas muaj tsawg C atoms: 2CH₃Cl (chloromethane) +2Na →CH₃- CH₃ (ethane) +2NaCl.
- Dej decomposition ntawm methanides (hlau carbides): Al₄C₃+12H₂O→4Al(OH₃)↓+3CH₄↑.
Lub cev muaj zog ntawm saturated hydrocarbons
Rau qhov yooj yim, cov ntaub ntawv tau muab tso rau hauv ib lub rooj.
| Formula | Alkane | Melting point in °С | Boiling point in °С | Density, g/ml |
| CH₄ | Methane | -183 | -162 | 0, 415 at t=-165°С |
| C₂H₆ | Ethan | -183 | -88 | 0, 561 ntawm t=-100°C |
| C₃H₈ | Propane | -188 | -42 | 0, 583 at t=-45°C |
| n-C₄H₁₀ | n-Bhutan | -139 | -0, 5 | 0, 579 at t=0°C |
| 2-Methylpropane | - 160 | - 12 | 0, 557 at t=-25°C | |
| 2, 2-Dimethyl propane | - 16 | 9, 5 | 0, 613 | |
| n-C₅H₁₂ | n-Pentane | -130 | 36 | 0, 626 |
| 2-Methylbutane | - 160 | 28 | 0, 620 | |
| n-C₆H₁₄ | n-Hexane | - 95 | 69 | 0, 660 |
| 2-Methylpentane | - 153 | 62 | 0, 683 | |
| n-C₇H₁₆ | n-heptane | - 91 | 98 | 0, 683 |
| n-C₈H₁₈ | n-Octane | - 57 | 126 | 0, 702 |
| 2, 2, 3, 3-Tetra-methylbutane | - 100 | 106 | 0, 656 | |
| 2, 2, 4-Trimethyl-pentane | - 107 | 99 | 0, 692 | |
| n-C₉H₂₀ | n-Nonan | - 53 | 151 | 0, 718 |
| n-C₁₀H₂₂ | n-Dean | - 30 | 174 | 0, 730 |
| n-C₁₁H₂₄ | n-Undecane | - 26 | 196 | 0, 740 |
| n-C₁₂H₂₆ | n-Dodecane | - 10 | 216 | 0, 748 |
| n-C₁₃H₂₈ | n-Tridecane | - 5 | 235 | 0, 756 |
| n-C₁₄H₃₀ | n-Tetradecane | 6 | 254 | 0, 762 |
| n-C₁₅H₃₂ | n-Pentadecane | 10 | 271 | 0, 768 |
| H-C₁₆H₃₄ | n-Hexadecane | 18 | 287 | 0, 776 |
| n-C₂₀H₄₂ | n-Eicosan | 37 | 343 | 0, 788 |
| n-C₃₀H₆₂ | n-Triacontan | 66 |
235 ntawm 1 mmHg st |
0, 779 |
| n-C₄₀H₈₂ | n-Tetracontan | 81 |
260 ntawm 3 mmHg st. |
|
| n-C₅₀H₁₀₂ | n-Pentacontan | 92 |
420 ntawm 15 mmHg st. |
|
| n-C₆₀H₁₂₂ | n-Hexacontane | 99 | ||
| n-C₇₀H₁₄₂ | n-Heptacontane | 105 | ||
| n-C₁₀₀H₂₀₂ | n-Hectane | 115 |
Zoo kawg
Cov kab lus suav tias yog lub tswv yim xws li alkanes (cov qauv, npe, isomerism, homologous series, thiab lwm yam). Ib me ntsis yog qhia txog cov yam ntxwv ntawm radial thiab hloov nomenclature. Cov txheej txheem kom tau txais alkanes tau piav qhia.
Tsis tas li ntawd, tag nrho cov npe ntawm alkanes tau teev nyob rau hauv nthuav dav hauv kab lus (kev sim tuaj yeem pab ua kom cov ntaub ntawv tau txais).
