Cho mng c gio v cc bn n tham gia bui tho lun mn Ha hc hu c.

Ni dung bi tho lun:V s hnh thnh lin kt cng ha tr trong phn t 2-metylpentan v penten-12. Nu cc phng php tch bit v tinh ch hp cht hu c 3. Trnh by v Hirocacbon no.

1.1. S hnh thnh lin kt cng ha tr trong phn t 2-metylpentan: 1 AOs lai ha vi 3 AOp 4 orbitan lai ha sp3 ca nguyn t CHnh 1: S hnh thnh lai ha sp3

Phn t 2-metylpentan: CH3-CH-CH2-CH2-CH3CH3

1.2. S hnh thnh lin kt cng ha tr trong phn t penten-1:

Hnh 2: S hnh thnh cc lin kt trong phn t penten-1: CH2=CH-CH2-CH2-CH3.

2. Cc phng php tch bit v tinh ch hp cht hu c.2.1. Phng php chng ct2.1.1. Chng ct thng (chng ct n gin, chng ct n)2.1.2. Chng ct phn on2.1.3. Chng ct li cun hi nc2.2. Phng php kt tinh (phng php kt tinh li)2.3. Phng php chit2.3.1. Chit trong h cht rn - lng2.3.2. Chit trong h cht lng - lng2.4. Phng php thng hoa2.5. Phng php sc k

2.1.1. Chng ct thng (chng ct n gin, chng ct n)Chng ct n gin p sut thng dng tch bit cht bn khi un nng v thc t khng b phn hy nhit si. Phng php ny thng dng vi cc cht c nhit si cao hn 40oC v thp hn 160oC v nhng cht lng si thp hn 40oC s mt i nhiu sau khi chng ct nn khng c hiu qu.Nu chng ct s dng ng sinh hn, th cc ng sinh hn ny thng c lp xui cht ngng t thu c bnh hng. Tc ct thng t 1-2 git cht lng ri vo bnh hng trong mt giy. cht lng si u v trnh hin tng qu la s khng c hin tng si vi biu hin cc ht cht lng chuyn ng trn b mt cht lng, dn n hin tng thnh thong cht lng si tro mnh v trn sang bnh hng, cn phi cho vo bnh ct mt t bt, hay ng mao qun hn kn mt u vo ngay khi bt u un nng.Ch khng c cho bt vo bnh ct khi ang si.

Hnh 2. 1. H thng chng ct n gin p sut thng(1: bnh cha mu chng ct, 2: nhit k, 3: ng sinh hn lp xui, 4: sng b, 5: bnh hng)

Hnh 2. 2. H thng chng ct n gin p sut thp(1: bnh cha mu chng ct, 2: ng mao qun, 3: van, 4: nhit k, 5: ng sinh hn lp xui, 6: sng b, 7: bnh hng, 8: van thng vi p sut kh quyn, 9: ng ch T, 10: bnh bo him, 11: p k)

Hnh 2. 3. H thng chng ct n gin p sut thng trong phng th nghim

Hnh 2.4. H thng chng ct hin i

Ha cht v dng c: Ha cht: nc my, KMnO4, H2SO4 c.Dng c: nhit k, bnh cu y trn dung tch 250ml, sinh hn thng, sng b, bnh tam gic.Cch tin hnh:Cho vo bnh cu y trn 100ml nc my, 0,1g KMnO4 v 0,01ml H2SO4 c, 2 vin bt v lp rp thit b nh hnh v:V d: Chng ct nc bng phng php chng ct n gin p sut kh quyn:

Ct b giai on u 10ml, tip ly 80ml v lun theo di nhit trong qu trnh ct. Ch un nng bnh cu vi tc 25 git/pht khng un qu mnh, ct vi tc nhanh s gy hin tng qu nhit, lm cho vic c nhit si khng ng v sn phm cho ra khng tinh khit.

2.1.2. Chng ct phn onChng ct phn on c dng c c mt tinh khit cao ca phn ct hay chng ct nhiu cht khc nhau t mt hn hp. Nu nhit si gn nhau c th chng ct di p sut thp hn ci thin bc tch v nh th nhit si s nm xa nhau hn.

Ha cht v dng c:Ha cht: axeton, toluenDng c: nhit k 200oC; ct vigr; bnh cu y trn 250ml; sinh hn thng; sng b; bnh hng.-Cch tin hnh: Cho vo bnh cu y trn 50ml axeton (si 56,4oC), 50ml toluen (si 110,6oC) v 3 vin bt, lp dng c nh hnh v sau:V d: S dng chng ct phn on phn tch hn hp axeton toluen:

un v ct vi tc 20 git/pht, theo di nhit v ly lm 3 on: on 1 si 56 - 70oC, on 2 si 70 - 100oC, on 3 si 100 110,6oC. Thay bnh ct nh hn ri cho phn on 1 vo ct ly axeton tinh khit 56 58oC. Phn cn li cho vo phn on 2. Cho phn on 3 vo v ct ly toluen tinh khit 110,6oC, on si trc cho vo phn on 2. Nh vy phn on 1 v 3 ta s thu c axeton v toluen tinh khit.

2.1.3. Chng ct li cun hi ncBn cht ca phng php li cun hi nc l lm bay hi cc hp cht hu c c nhit si cao, khng tan hoc t tan trong nc bng cch sc hi nc vo hn hp ca cc cht v nc. Kt qu l cht hu c v nc s ngng t sinh hn v ch xung bnh hng. Phng php ct li cun hi nc thng dng tch ring cc cht hu c lng t tan trong nc nhit < 100oC nh chng ct nhiu loi tinh du c gi tr trong y dc v i sng nh tinh du bc h, qu, hi.

2.2. Phng php kt tinh (phng php kt tinh li)

Kt tinh l qu trnh hnh thnh v pht trin ca tinh th t tng nng chy, dung dch hay kh. Phng php kt tinh li l phng php tinh ch quan trng da trn tnh bo ha ca cht rn cn tinh ch khi un nng trong dung mi thch hp, loi b cht ph v cht kt tinh tr li khi lm lnh. Qu trnh kt tinh li gm cc giai on sau: - Ha tan mu cht rn khng tinh khit trong dung mi thch hp - Lc nng dung dch trn loi b cht ph khngtan - Lm lnh dung dch hoc ui bt dung mi to dung dch bo ha v gy mm kt tinh - Lm kh tinh th. Quy trnh ny c th lm li nhiu ln thu c cht tinh khit.

3. Hirocacbon no3.1. nh ngha:Hirocacbon no l nhng Hirocacbon m trong phn t ch c nhng nguyn t cacbon no Csp3 v do ch c nhng lin kt n.

3.2. Phn loi:C 2 loi: Hirocacbon no mch h gi l ankan, cng thc chung CnH2n+2 (n>=1)

Hirocacbon no mch vng gi l xicloankan cng thc chung CnH2n (n>=3) i vi xicloankan n vng.

V d:

V d:

3.3. Cu trc phn t3.3.1. Ankan.Phn t ankan ch c nhng nguyn t Csp3 vi gc ha tr ~109,5o do mch cacbon thng l ziczac v tn ti ch yu dng xen k, v l nhng dng bn.Cc lin kt C-C v C-H trong ankan khng phn cc hoc ch phn cc rt yu. Nng lng ca cc lin kt thay i theo bc ca nguyn t cacbon, song ni chung l ln ( khong 350-400kJ/mol). V vy hu ht cc phn ng ca ankan thng xy ra theo kiu ng li.

V d: Phn t nonan:V d: Phn t propan

3.3.2. Xicloankan.Xiclopropan v xiclobutan l nhng vng km bn. Do gc CCC b p nhiu so vi gc bnh thng (109,5o), lin kt C-C trong phn t xiclopropan c hnh thnh bng cch xen ph mt bn, chnh v vy lin kt ny km bn.Xiclopentan v xiclohexan l nhng vng bn. Vng xiclohexan c dng gh nn cc gc lin kt t din vn c m bo cn cc nguyn t hiro lun lun v tr xen k.

M hnh xiclopentanM hnh xiclopropan

3.4. Tnh cht3.4.1. Tnh cht vt l: i vi ankan: t C1 n C4 l cht kh, t C5 n C19 l cht lng v t C20 tr ln l cht rn. Khi phn t khi ca ankan tng ln th nhit si v nhit nng chy cng tng ln.Cc ankan u nh hn nc. Khi lng ring ca ankan tng theo mch cacbon, ti a l 0.8g/mlCc ankan u khng tan (hoc rt t tan) trong nc. Ngc li chng tan trong cc dung mi hu c, ha tan c cht bo.

-Trong ph hng ngoi ca cc ankan xut hin cc s sng ca dao ng ha tr C H 2960 2850 cm-1. Nhm metyl v metylen c cc dao ng bin dng C H c trng trong vng 1470 1350 cm-1.-Trn ph t ngoi gn ( t 200 nm n 400 nm) khng c cc i hp th ca ankan, v th mt s ankan c dng lm dung mi ha tan cc cht cn ghi ph t ngoi.

-Ph cng hng t proton (1H-NMR) ca ankan c cc tn hiu c trng 0.9 ppm ( nhm CH3); 1,25 ppm (nhm - CH2 - ) v 1.5 2.0 ppm (nhm CH - ), ta c th nhn bit c mt ankan c phn nhnh hay khng.

3.4.2. Tnh cht ha hc1.Phn ng th:Phn ng ch xy ra vi Clo hoc Brm khi chiu sng. It khng phn ng, cn Flo th phn hu ankan thnh C v H2.Khi chiu sng hoc t nng hn hp metan v clo s xy ra phn ng th ln lt cc nguyn t hiro bng clo:

CH4 + Cl2 CH3Cl + HCl metyl clorua (clometan) CH3Cl + Cl2 CH2Cl2 + HCl metylen clorua (iclometan) CH2Cl2 + Cl2 CHCl3 + HCl clorofom (triclometan) CHCl3+Cl2 CCl4 + HCl cacbon tetraclorua(tetraclometan)

C ch phn ng halogen ha ankan Phn ng clo ha v brom ha ankan xy ra theo c ch gc - dy chuyn. Bc khi mo: Bc pht trin dy chuyn: Bc t dy chuyn:

Ch thch:(1): Phn t clo hp th nh sng b phn ct ng li thnh2nguyn t clo. (2): Nguyn t clo l mt gc t do hot ng, n ngt ly nguyn tHtCH4to raHClv gc t do.CH3. (3): Gc.CH3khng bn, n tch ly nguyn tCltCl2 tr thnhCH3Clbn hn. Nguyn tCl.mi sinh ra phn ng(3)li tc dng viCH4lm cho phn ng(2)v(3)lp i lp li ti hng chc ngn ln nh mt dy chuyn. (4)(5)(6): Cc gc t do kt hp vi nhau thnh cc phn t bn hn

Phn ng ca xicloankan vi halogenXiclobutan+ HNO3450oCNO2+ H2OXiclohexanNitroxiclohexan+ Cl2nh sngCl+ HClCloxiclobutanXiclohexan, xiclobutan tc dng vi Halogen cho sn phm th, tng t ankan.

2. Phn ng tcha) hir ho (tch hir):Ankan mch ngn khi un nng vi xc tc Cr2O3, Cu, Pt th to thnh anken v H2. Th d: Ring CH4 tu theo nhit s cho cc phn ng: Phn ng tch hiro nhng ankan c 5-7 nguyn t cacbon trong mch chnh c th dn ti s ng vng hoc xa hn na l thm ha. Th d:CH2CH2CH2CH2CH3CH3Xt, to -H2Xt, to -3H2

b) Crckinh -Crckinh l qu trnh b gy mch cacbon ca cc ankan mch di thnh anken v ankan mch ngn hn. Crckinh nhit thc hin 600oC, cn crckinh xc tc Al2(SiO3)3 thc hin 450oC 550oC. Qu trnh ny b gy bt k lin kt C - C no v gi l crckinh xc tc.Th d:CH3-CH2-CH3crckinhCH4 + CH2=CH2CH3-CH2-CH2-CH3crckinhCH4 + CH3-CH=CH2CH3CH3 + CH2=CH2

ng dng ca phn ng crckinh ankan: Trong cng nghip du m, qu trnh ny dng bin i cc phn on nng thnh sn phm nh, c nhit si gn bng nhit si ca hirocacbon trong xng. Crckinh xc tc vi s c mt ca hiro th s nhn c sn phm l cc hirocacbon no c mch ngn hn:CH3(CH2)10CH3 Cht xc tcH2, toCH3(CH2)3CH3 + CH3(CH2)5CH3Ankan mch diAnkan mch ngn hn

Cn trong nhng trng hp crckinh m khng c mt hiro, sn phm phn ng l hn hp ca ankan v anken c mch ngn hn:CH3(CH2)10CH3toCht xc tcCH3CH=CHCH2CH3 + CH3(CH2)5CH3Ankan mch diHn hp anken v ankan c mch ngn hn

3. Phn ng oxi ha:a)Phn ng oxi ha hon ton (phn ng chy):

- ankan- xicloankan CnH2n +3n 2O2tonCO2 + nH2OCnH2n+2 +3n + 1 2O2tonCO2 + (n + 1)H2OKhi c tia la t v oxi, ankan v xicloankan chy hon ton sinh ra O2, H2O v ta nhit mnh:

b) Phn ng oxi ha khng hon ton:- Oxi ha metan:CH4O2 khng kh200at, 300oC, CuHCH=O + H2OC + 2H2O (bt than)t thiu khng khCO2 + 2H2 (kh t)500oC, Ni- Oxi ha ankan cao:R-CH2R-CH2R-COONa + R-COONa R-COOH + R-COOHNaOHxt mui mangan (x phng)O2 khng kh

- Oxi ha xiclohexanO2, 40at 150oCOHO2, NOXiclohexanonOZnO, toNilon-6Nilon-6,6

Hot tnh sinh hc ca ankan:Trong vi khun v vi khun c:-Vi khun csn xut mtan trong d dy con b l nguyn nhn to ra mt lng nhmtantrong kh quyn Tri t.-Mt s loivi khunnht nh c th chuyn ha cc ankan: chng a thch cc ankan c mch cacbon chn do chng d b phn hy hn so vi ankan mch cacbon l.Mt khc mt svi khun c nhmtanogen, sn sinh ra mt lng ln mtan bng cch chuyn hacacbon ixthoc xi ha cc hp cht hu c khc. Nng lng c gii phng bng s xi hahir:CO2+ 4H2 CH4+ 2H2O

Cc ankan cng ng vai tr nh trong sinh hc ca ba nhmeukaryotl:nm,thc vtvng vt. Mt s loi men c bit, v dCandida tropicale, cc loi hPichia,Rhodotorula, c th s dng ankan nh l ngun cacbon v/hoc nng lng. Loi nmAmorphotheca resinaea thch cc ankan mch di trongnhin liu hng khng, v c th sinh ra cc vn nghim trng cho my bay trong cc khu vc nhit i.Trong thc vt ngi ta cng tm thy cc ankan rn mch di; chng to ra mt lp sp rn chc-lpcutin(biu b), trn cc khu vc m thc vt b lt trn ra ngoi khng kh. N bo v thc vt chng li s mt nc, ng thi ngn cn s tht thot ca cc khong cht quan trng do b ma. N cng bo v thc vt chng li vi khun, nm v cccn trngc hi. Lp v sng mu trn cc loi qu nh to cng cha cc ankan mch di. Mch cacbon thng thng nm gia 20 v 30 nguyn t cacbon v c thc vt sn xut t ccaxt bo. Thnh phn chnh xc ca lp sp khng ch ph thuc vo loi m cn thay i theo ma v cc yu t mi trng nh iu kin chiu sng, nhit v m.

Nc to thnh cc git nh trn mng mng cha sp ankan ph bn trn v qu to.

- Cc ankan cng c tm thy trong cc sn phm ca ng vt, mc d chng t quan trng hn so vi cc hydrocacbon khngno. Mt v d l du gan c mp cha khong 14%pristan(2,6,10,14-tetramtylpentadecan, C19H40). S c mt ca chng l quan trng hn trong ccpheromon, loi ha cht lm tn hiu, m gn nh ton b cn trng u cn khi lin lc vi nhau. Vi mt s loi, nh c s dng bi b cnh cngXylotrechus colonus, ch yu lpentacosan(C25H52), 3-mtylpentaicosan (C26H54) v 9-mtylpentaicosan (C26H54), chng c chuyn giao bng s tip xc c th. Vi cc loi khc nhmui x xGlossina morsitans morsitans, pheromon cha 4 ankan l 2-mtylheptadecan (C18H38), 17,21-imtylheptatriacontan (C39H80), 15,19-imtylheptatriacontan (C39H80) v 15,19,23-trimtylheptatriacontan (C40H82), v chng hot ng bng mi vi mt khong cch ln, mt c trng hu ch kim sotsu b.

Mt v d v ankan m c trn ng v thc vt u c vai tr l quan h sinh thi giaong ct(Andrena nigroaenea) vlan hnh nhn (Ophrys sphegodes); trong hoa lan ph thuc vo sth phnca ong. Ngoi ra, ong ct s dng cc pheromon xc nh bn tnh ca mnh; trong trng hp caA. nigroaenea, con ci s dng hn hp catricosan(C23H48),pentacosan(C25H52) vheptacosan (C27H56) vi t l 3:3:1, v con c b hp dn bi mi c trng ny. Cy hoa lan nm c u th ny cc phn trong hoa ca n khng ch tng t nh b ngoi ca ong ct, m n cn sn xut ra mt lng ln c 3 ankan ni trn vi cng mt t l tng t. Kt qu l hng lot ong c b quyn r bay n v c gng giao hp vi bn tnh gi mo ca mnh: mc d n lc ny khng em li thnh cng cho ong, nhng n cho php cy lan chuyn giao phn hoa ca n, c gieo rc sau khi con c nn ch bay sang cc bng hoa khc.

Lan hnh nhn

3.5. iu ch:a)Trong cng nghip:Metan v cc ng ng c ly t kh thin nhin, kh m du (kh ng hnh) t du m v sn phm ch bin du m.

b) Trong phng th nghim:c th iu ch ankan t cc hirocacbon khng no tng ng, t dn xut halogen v t xeton.Ngi ta cn c th iu ch cc ankan thp bng cch nung khan mui ca natri cacboxylic (C2 C4) vi NaOH ( dng vi ti xt). Th d:CH3COONa + NaOH (rn) to CaOCH4 + Na2CO3

3.6. ng dng:a)Nhin liu:-Trong Kh du m ha lnghayKh ha lng (Liquefied Petroleum Gas; vit tt:LPG).y l cch din t chung capropanc cng thc ha hc l C3H8vbutanc cng thc ha hc l C4H10, c hai c tn tr ring bit hoc chung vi nhau nh mt hn hp. LPG c gi l kh du m ha lng v cc cht kh ny c th c ha lng nhit bnh thng bng cch gia tng p sut va phi, hoc p sut bnh thng bng cch s dng k thut lm lnh lm gim nhit . Trong thnh phn ca LPG, thng thng,propanchim 50%,butanchim 50%.

ng dng trong kh ha lng.

- S dng lm nhin liu trong cc ng c t trong. T pentan tioctanth ankan l cc cht lng d bay hi, do chng d ha hi khi i vo trong khoang t m khng to ra cc git nh c th lm h hi tnh ng nht ca s chy. Cc ankan mch nhnh c a chung hn, do chng c s bt chy mun hn so vi cc ankan mch thng tng ng (s bt chy sm l nguyn nhn sinh ra cc ting n lc xc trong ng c v d lm h hi ng c). Bn cnh vic s dng nh l ngun nhin liu th cc ankan ny cn ldung mitt cho cc cht khng phn cc.

ng dng lm nhin liu cho cc loi ng c t trong

- Cc ankan tnonanti hexadecan(ankan vi mch cha 16 nguyn t cacbon) l cc cht lng c nht cao, t ph hp cho mc ch s dng nh lxng. Ngc li, chng to ra thnh phn ch yu ca du izen v nhin liu hng khng. Cc nhin liu izen c nh gi theo ch s cetan (cetan l tn gi c ca hexadecan). Tuy nhin, im nng chy cao ca cc ankan ny c th sinh ra cc vn nhit thp v ti cc vng gn cc Tri t, khi nhin liu tr nn c qunh hn v s truyn dn ca chng khng c m bo chun xc.

Dng lm nhin liu cho ng c t, xe my.

Dng lm nhin liu cho my bay

Dng lm nhin liu cho my pht in

-Cc ankan t hexadecan tr ln to ra thnh phn quan trng nht ca cc loi cht t trong cc l t v du bi trn. chc nng sau th chng lm vic nh l cc cht chng g do bn cht khng a nc ca chng lm cho nc khng th tip xc vi b mt kim loi. Nhiu ankan rn c s dng nh l parafin, v d trong cc loi nn. Khng nn nhm lnparafinvi sp thc s (v d sp ong) ch yu l hn hp ca cceste.

ng dng ankan trong Du chng g st v bi trn RP7

ng dng ankan trong Du m bi trn ng c

ng dng ankan trong vic sn xut cc loi nn

-Cc ankan vi di mch cacbon khong t 35 tr ln c tm thy trong bitum, c s dng ch yu trong nha ng ri ng.

b) Nguyn liu cng nghip ha hc:T metan sn xut ra axetilen, mui than v hiro, ru etylic, phenol, cumen, axeton

+ Cng nghip ha hc cn metan lm nguyn liu c bn cho tng hp hu c. Nhit phn metan trong nhng iu kin khc nhau c th sinh ra axetilen hoc mui than cng vi hiro:2CH41400 1500oCHCCH + 3H2CH41000oC, xtC + H2

+ T metan sn xut ru eylic:2CH4HgSO41500oCLm lnh nhanhC2H2 + 3H2C2H2 + H2O80oCCH3CHOCH3CHO + H2NitoC2H5OH

+ T metan sn xut phenol:2CH41500oCLm lnh nhanhC2H2 + 3H23C2H2600oC+ Cl2FeClCl+ NaOH360oC300atmOH+ NaCl

+ T metan sn xut cumen v axeton:2CH41500oCLm lnh nhanhC2H2 + 3H23C2H2600oC+ CH2=CH-CH3H+CH3-CH-CH3(cumen)CH3-CH-CH3+ O2xtOH+ CH3 CO CH3

Mt s ng dng trong i sng ca axeton

T butan sn xut axit axetic2C4H10 + 5O24CH3COOH +2H2O to, xt

- T cc ankan C25 C30 sn xut x phng2CH3(CH2)14CH2CH2(CH2)14CH3O2, to, xt2CH3(CH2)14COOH2CH3(CH2)14COOH + Na2CO32CH3[CH2]14COONa + H2O + CO2

HTChc bui tho lun thnh cng tt p!

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