C´ng ngh»‡ H³a d§u - Nguy»…n Th»‹ Di»‡u H±ng

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Text of C´ng ngh»‡ H³a d§u - Nguy»…n Th»‹...

  • CHNG I: QU TRNH ALKYL HA

    Qu trnh alkyl ha l qu trnh a cc nhm alkyl vo vo phn t cc cht

    hu c hoc v c. Cc phn ng alkyl ha c gi tr thc t cao trong vic a cc

    nhm alkyl vo hp cht thm, izoparafin, mercaptan, sulfid, amin, cc hp cht

    cha lin kt ete... ngoi ra qu trnh alkyl ha l nhng giai on trung gian trong

    sn xut cc monome, cht ty ra...

    1. C TRNG CA QU TRNH ALKYL HA

    I. Phn loi cc phn ng alkyl ha

    S phn loi hp l nht cc qu trnh alkyl ha l da trn loi lin kt

    c hnh thnh.

    1. Alkyl ha theo nguyn t C: cn gi l qu trnh C - alkyl ha

    C - alkyl ha l th nguyn t H gn vi C bng cc nhm alkyl.

    CnH2n+2 + CmH2m Cn+mH2(n+m)+ 2

    ArH + RCl ArR + HCl

    2. Alkyl ha theo nguyn t O v S: cn gi l qu trnh O - alkyl ha v S -

    alkyl ha

    O - alkyl ha v S - alkyl ha l cc phn ng dn n to thnh lin kt gia

    nhm alkyl v nguyn t O hoc S.

    ArOH + RCl + NaOH ArOR + NaCl + H2O

    NaSH + RCl RSH + NaCl

    3. Alkyl ha theo nguyn t N: cn gi l qu trnh N - alkyl ha

    N - alkyl ha l th cc nguyn t H trong amoniac hoc trong amin bng

    cc nhm alkyl. y chnh l mt trong nhng phng php quan trng nht

    tng hp cc amin.

    ROH + NH3 RNH2 + H2O

    4. Alkyl ha theo cc nguyn t khc:

  • Cc qu trnh Si -, Pb -, Al - alkyl ha... l con ng quan trng tng hp

    cc hp cht c nguyn t hoc c kim.

    2 RCl + Si R2SiCl2 (xc tc l Cu)

    4 C3H7Cl + 4 NaPb Pb(C3H7)4 + 4 NaCl + 3 Pb

    3 C2H4 + Al + 3/2 H2 Al(C2H5)3

    II. Cc tc nhn alkyl ha v xc tc

    Cc tc nhn alkyl ha c th chia lm 3 nhm:

    a) Cc hp cht khng no (olefin v acetylen), trong s ph v cc

    lin kt pi ca cc nguyn t C.

    b) Dn xut Cl vi cc nguyn t Cl linh ng c kh nng th di nh

    hng ca cc tc nhn khc nhau.

    c) Ru, ete, este, oxyt olefin l cc tc nhn m trong qu trnh alkyl

    ha lin kt C - O s b ph v.

    1. Tc nhn l olefin - xc tc v c ch

    Trong cc loi tc nhn th tc nhn olefin c gi thnh kh r, v vy ngi

    ta lun c gng s dng chng trong mi trng hp c th. Cc olefin

    (etylen, propylen, buten v cc olefin cao phn t) ch yu c s dng

    C - alkyl ha cc parafin v cc hp cht thm.

    Xc tc: acid proton (a.Bronsted) hoc acid phi proton (a.Lewis)

    C ch: ch yu xy ra theo c ch ion qua giai on trung gian hnh thnh

    cacbocation. Kh nng phn ng ca cc olefin c nh gi bng mc

    to ra cacbocation:

    RCH = CH2 + H+ RC+H - CH3

    Qu trnh ny chu nh hng ca s tng chiu di mch, phn nhnh

    ca olefin:

    CH2 = CH2 < CH3 - CH = CH2 < CH3 - CH2 - CH = CH2 < (CH3)2C = CH2

  • Tc nhn olefin c mch cng di, cng phn nhnh th kh nng phn

    ng cng ln.

    Ngoi ra trong rt nhiu trng hp, qu trnh alkyl ha bng olefin c th

    xy ra di tc dng ca cc cht khi mo phn ng chui gc, hoc tc

    dng ca nh sng hoc tc dng ca nhit cao. Khi cc phn t trung

    gian l cc gc t do v trong trng hp ny kh nng phn ng ca cc

    olefin c cu to khc nhau cng khng khc nhau nhiu.

    2. Tc nhn l cc dn xut clo - xc tc v c ch

    Cc dn xut clo c xem l cc tc nhn alkyl ha tng i thng dng

    nht trong cc trng hp O -, S -, N - alkyl ha v tng hp phn ln cc

    hp cht c kim, c nguyn t; ngoi ra cn c s dng trong trng hp

    C - alkyl ha.

    C - alkyl ha : xy ra theo c ch i in t di tc dng cht xc tc l cc

    acid phi proton (FeCl3, AlCl3) qua giai on trung gian hnh thnh

    cacbocation:

    RCl + AlCl3 R+ Cl -AlCl3 R+ + AlCl4-

    Kh nng phn ng ca cc alkyl clorua ph thuc vo phn cc ca lin

    kt C-Cl hoc vo bn cacbocation v s tng khi chiu di v mc

    phn nhnh ca nhm alkyl tng:

    CH3CH2Cl < (CH3)2CHCl < (CH3)CCl3

    O -, S-, N - alkyl ha : xy ra theo c ch i nhn v khng cn xc tc

    RCl + :NH3 RN+H3 + Cl- RNH2 + HCl

    Kh nng phn ng ca cc dn xut clo c sp xp theo dy:

    ArCH2Cl > CH2 = CH - CH2Cl > AlkCl > ArCl

    v AlkCl bc I > AlkCl bc II > AlkCl bc III

    Trong tng hp c kim v c nguyn t : xy ra theo c ch gc t do di

    tc dng ca kim loi

  • 4 NaPb + 4 C2H5Cl 4 Pb + NaCl + 4 C2H5

    4 NaCl + Pb(C2H5)4 + 3 Pb

    3. Tc nhn l cc hp cht c cha O - xc tc v c ch

    Cc tc nhn alkyl ha c cha O nh ru, ete, este, oxyt olefin c th dng

    trong cc qu trnh C -, O -, N - v S - alkyl ha; tuy nhin trn thc t ngi

    ta s dng ch yu l cc oxyt olefin. Qu trnh xy ra theo c ch

    cacbocation di tc dng ca xc tc l acid proton lm t lin kt gia

    nhm alkyl v oxy:

    ROH + H+ R - +OH2 R+ + H2O

    III. c tnh nng lng ca cc phn ng alkyl ha

    Cc c tnh nng lng ph thuc vo tc nhn alkyl ha v dng lin kt b

    ph v trong cht alkyl ha. Mt s thng s nng lng trong qu trnh alkyl ha

    c trnh by bng sau:

    Tc nhn alkyl ha Lin kt b ph v -Ho298 , kJ/mol

    RCH = CH2C - HCar - HO - H

    84 10096 10450 63

    RClCar - HO - HN - H

    34 42 00 25

    ROH O - HN - H0 2121 42

    CH2 - CH2 O O - H 88 104

    CH CH O - H 100 117

  • 2. ALKYL HA THEO NGUYN T CACBON

    Qu trnh C - alkyl ha ch yu xy ra vi cc hp cht thm v parafin vi

    nhiu nghi thc t to ln.

    I. Alkyl ha cc hp cht thm

    1. Ha hc v c s l thuyt

    1.1. Xc tc

    Tu thuc vo tc nhn alkyl ha m c th s dng cc xc tc khc nhau.

    Cc tc nhn alkyl ha hydrocacbon thm s dng ch yu trong cng nghip

    l cc dn xut clo v olefin. Ru t c s dng cho qu trnh alkyl ha

    hydrocacbon thm v c kh nng alkyl ha km hn.

    Khi tc nhn l cc dn xut clo: xc tc hu hiu nht l cc acid phi

    proton, ph bin nht l AlCl3. Hn hp phn ng trong pha lng khi alkyl

    ha vi xc tc AlCl3 bao gm 2 pha: phc xc tc v lp hydrocacbon.

    Khi tc nhn l olefin: thng dng xc tc l AlCl3; ngoi ra c th dng

    a.H2SO4, HF, H3PO4 trn cht mang, aluminosilicat, zeolit... Trong :

    o Khi xc tc l a.H2SO4 hoc HF: + qu trnh pha lng

    + t = 10 40oC

    + p = 0,1 1 MPa

    o Khi xc tc l a.H3PO4 rn: + qu trnh pha kh

    + t =225 275oC

    + p = 2 6 MPa

    o Khi xc tc l aluminosilicat, zeolit: + qu trnh pha lng hoc pha kh

    + t = 200 400oC

    + p = 2 6 MPa

    Nh vy, i vi qu trnh C-alkyl ha th xc tc AlCl3 chim v tr p o

    v c nhiu u th.

  • AlCl3 trng thi rn hu nh khng tan trong hydrocacbon v xc tc rt

    yu cho phn ng. Tuy nhin theo mc hnh thnh HCl, AlCl3 bt u chuyn

    qua trng thi lng c mu sm. Cht lng ny mc d khng tan trong

    hydrocacbon nhng c hot tnh rt ln v do tc phn ng s tng ln. Trng

    thi hot ng ca AlCl3 c th chun b bng cch sc kh HCl qua h huyn ph

    ca AlCl3 trong hydrocacbon, khi s hnh thnh phc ca AlCl3 v HCl vi 1 n

    6 phn t hydrocacbon thm, trong mt phn t ny nm trng thi cu trc

    c bit mang in tch dng (phc ) cn cc phn t cn li hnh thnh lp

    solvat:

    Nhm t c vn tc alkyl ha cao ngay t thi im bt u phn ng,

    phc ny thng c chun b trc ri sau a vo h phn ng.

    1.2. C ch phn ng

    1.2.1. Khi tc nhn l dn xut Clo RCl: xc tc AlCl3 s hot ha Cl to ra

    phc phn cc mnh (phc ) v hnh thnh cacbocation

    RCl + AlCl3 R+ Cl -AlCl3 R+ + AlCl4-

    1.2.2. Khi tc nhn l olefin: xc tc AlCl3 s kt hp vi cht ng xc tc l

    HCl to ra cacbocation

    RCH = CH2 + HCl + AlCl3 RC+H - CH3 + AlCl4-

    Trong trng hp ny cu to ca nhm alkyl trong sn phm c xc nh

    theo nguyn tc v s to thnh cacbocation bn vng nht giai on trung gian

    (bc III > bc II > bc I).

    1.3. Cc phn ng ph

    Cc phn ng ph c th xy ra trong qu trnh alkyl ha hydrocacbon thm:

    RR+ H

    R+ R+ + H+

    . (n-1) ArHHH Al

    2Cl

    7 -

  • Alkyl ha ni tip

    Nha ha

    Phn hy cc nhm alkyl

    Polyme ha olefin

    Phn ng alkyl ha ni tip:

    Khi alkyl ha cc hp cht thm vi s c mt ca xc tc bt k s xy ra

    s th ni tip cc nguyn t H v to thnh hn hp sn phm vi mc alkyl

    ha khc nhau.

    V d khi etyl ha C6H6 s xy ra n khi to thnh hexa etylbenzen:

    Mi phn ng trong dy ny u l cc phn ng bt thun nghch. Tuy

    nhin khi dng xc tc Aluminosilicat hoc Zeolit iu kin tng i khc

    nghit hoc khi dng xc tc AlCl3 th s xy ra phn ng thun nghch vi s dch

    chuyn v tr ca cc nhm alkyl:

    Kh nng dch chuyn v tr ca cc nhm alkyl c sp xp theo dy:

    (CH3)3C- > (CH3)2CH- > CH3 - CH2- >> CH3-

    Cc kh nng hnh thnh sn phm ni tip:

    C6H

    6C

    6H

    5 - C

    2H

    5

    + C2H

    4+ C

    2H

    4 C6H

    4- (C

    2H

    5)

    2

    + C2H

    4 C6H

    3- (C

    2H

    5)

    3 v.v.

    C6H

    4R

    2 + C

    6H

    62 C

    6H

    5R

    C6H

    3R

    3 + C

    6H

    6 C

    6H

    5R + C

    6H

    4R

    2

    + R+

    + R+

    RR

    + R+

    RR R

    R+ R+

    RR

    RRR R

    R

    RR

  • Phn ng nha ha

    Nguyn nhn l do cc vng thm ngng t nhit cao to thnh cc sn

    phm nh diarylalkan, triarylalkan, diarylolefin ... Nhit cng tng phn ng

    nha ha hnh thnh hp cht a vng s cng tng.

    Phn ng phn hy cc nhm alkyl

    Nguyn nhn l do khi iu kin phn ng khc nghit s thc y s phn

    hu cc nhm alkyl v to ra cc sn phm ph c mch alkyl ngn.

    V d: + Khi C3H6 phn ng vi C6H6 c hnh thnh sn phm C6H5-C2H5

    + Khi C2H4 phn ng vi C6H6 c hnh thnh sn phm C6H5-CH3.

    Mch alkyl cng di cng d b phn hy. S phn hu c kh nng xy ra

    giai on tch cacbocation.

    Phn ng polyme ha olefin

    Nguyn nhn l do s kt hp ni tip ca cacbocation vi olefin (trng hp

    cation)

    Polyme sinh ra c khi lng phn t khng ln v c th hn ch bng lng

    d hydrocacb