TAP CHI HOA HOC
DOI: 10.15625/0866-7144.2015-0078
T. 53(1)6-12 THANG 2 NAM 2015
NGHIEN CLPU LJ THUYET P H A N U'NG CUA G 6 C P R O P A R G Y L (C3H3) VA NU'O'C B A N G PHU'aNG PHAP PHI^M HAM MAT DO
Tran Hiru HuTig'*, Pham Van Tien^Nguyen Thi Minh Huf' 'BQ mon Hod, Truang Dgi hqc Kiin triic Hd Noi
^Vien Ky thudl Hoa hoc, Tnrang Dgi hoc Bach khoa Hd Noi
^Khoa Hod hgc va Trung tdm Khoa hoc Tinh todn- Tnrdng DHSP Ha Ngi Din Tda soan 22-5-2014; Chip nhin dang 13-2-2015
Abstract
The reaction mechanism of the propargyl radical (C3H3') and water (H2O) has been studied by the Density Functional Theory (DFT) using the B3LYP fimctional and the aug-cc-pvtz basis set. The potential energy surface (PES) for the C3H3 and H2O system was also established. Calculated results indicate that products of this reaction can be (HOCH2CCH -H H), (CH^CCHj + OH), (CH2=CH-CH0 -*- H), (C2H4 -i- HCO), (C2H5 + CO), (CH2-C-CH2 + OH), (C2H2 + CHjOH), (CHCHCHO + H2), (CHCHCHOH + H), (CH3 + CH2CO), (CHj^C-CHOH+H). However, the formation of (CH2=C=CH2 + OH) is the most favorable.
Keywords. Reaction mechanism, propargyl radical, water, density fiinctional theory.
1. MO DAU
Trong he ddt chay hidrocacbon cung nhu nhien lieu hda thach da hinh thanh cac hidrocacbon thorn da vdng va gdc propargyl (C3H3) dugc cho la cd vai trd quan trgng trong qua trinh hinh thanh cac hidrocacbon thorn dd [1]. Hien nay cd mgt so cdng trinh nghien curu thuc nghiem phan iing cua C3H3 vdi C3H3, O, NO2 [1-3]. va mdt sd cdng trinh nghien ciiu ly thuyet co che phan iing cua gdc C3H3 [4, 5]
da dugc cdng bd. Cac ket qua deu chi ra ring gdc C3H3 cd kha nang phan img cao va da dang. Nude la hgp chit phd blln trong khi quyln va dupe hinh thanh trong hiu hit ciia qua trinh ddt chay cac chit hiru CO. Da cd nhieu nghien ciru cua nude vdi cac goc tu do nhu: CCb, CH, C2H, CCI, CjF... [6-9]
nhung chua thiy cdng trinh nao cdng bd kit qua nghien cuii If thuylt ciing nhu thuc nghiem phan ling cua gdc C3H3 vdi H2O. Do vay vi?c nghien ciiu ly thuylt CO chi phan ihig ciia C3H3 vdi H2O khdng nhihig md r^ng hieu biit vl kha nang phan iing goc (C3H3) ma cdn giai thich dugc s\r hinh thanh cac san phim trong qua trinh chuyln hda tir C3H3.
2. PHUONG PHAP TINH
c i u true hinh hpc cua cac chit phan iing, cac chit trung gian, trang thai chuyln tilp va cac san pham diu dugc tdi uu theo phuang phap phiim ham mat dg d mirc B3LYP/aug-cc-pvtz [10]. Trong dd
trang thai chuyen tiep dung dugc xac thuc bing viec phin tieh tan sd dao ddng, tpa dp thuc (IRC) cua phan ling, tan sd dao ddng va tga do thy:c ciia phan ling se cho biit su thay ddi vl ciu true hinh hpc tiit chat dau den chit cudi, tren co sd dd rut ra ket lu?n trang thai chuyln tilp can tim cd chinh xac hay khdng. Ngoai ra dp nhiem spin (s^) cimg dugc xem xet. Nang lugng dilm don cung dugc tinh vdi bp ham CO sd B3LYP/aug-cc-pvtz, day la bp ham co tinh chinh xac dd tin cay cao. Tu cac kit qua nhan dupe se xac djnh ciu tnic, nang lugng, tinh cac thdng sd nhiet dpng d 298 K, ap suit I atm [11] va thiet lap be mat the nang cua he. Cac tinh toan dugc thuc hien tren phin mlm Gaussian 03 [12].
3. KET QUA VA T H A O LUAN
3.1. DUT doan kha nang phan irng
De so bd du doan hudng phan iing uu tien trong he C3H3 va H2O (can cii vao gia tri nang lugng tuong ddi AE), chiing tdi da tinh va phan tich nang Iugng cua cac obitan phan tu (MO), mgt sd kit qua dugc dua ra d bang 1.
Ap dung li thuylt obitan phan tii bien FMC (frontier molecular orbital) va kit qua tinh d bang cho thay, gia trj AE nhd nhat img vdi mirc nang lugng LUMOa cua H2O va HOMOa cua gdc C3H3 [14]. Do dd, khi phan iing xay ra thi miit dp electron
TCHH,T. 53(1),2015 Tran Hm Hung va C0ng su sg dich chuyen tir goc C3H3 sang phan tii H2O. Hinh anh cac obitan bien duac bieu dien a hinh I.
Bang 1: Gia tri nang lugng cCia HOMO va LUMO a B3LYP/aug-cc-pvtz E (HOIVIO) (hatree) E (LUMO) (hatree) AE(LUMO-HOMO) (hatree) C3H3 -0,22261 (HOMOa)
-0,28553 (HOMOP) H2O -0,32412 (HOMOo)
-0,00742 (LUMOa) -0,10445 (LUMOP) -0,02506(LUMOa)
C3H3(a) - H20(a) 0,31670 CjH3(P)-H20{a) 0,21967 H20(a) - C3H3(a) 0,19755 H;0(a) - C3Hj(P) 0,26047
HOMO
J
C3H3
\i
LUMO
h
HOMO
• ^^••1
ij
H ; 0 Lrxiu
W^ ti
\A
- —
^^n fc
Hinh T. Anh cac HOMO va LUMO cua C3H3 va HjO
Cac hudng phan umg cd the xay ra cua he phan img giira C3H3 vdi H2O dugc minh hga trong so dd hinh 2.
TS2/6 TS6/P3
P3 ( CjH4 + HCO )
* PI ( C2H5 + CO )
•P9 (HOCHjCCH + H)
* P10 (CHCHCHO + H J )
* P 1 1 (CHCHCHOH + H)
* P 5 (C2H2 + CHjOH) Hinh 2: So dd ca chi phan iing giira C3H3 vdi H2O
TCHH T 53(1) 2015 Nghien ciru lythuyiiphdn img cua goc...
3.2. Cau true hinh hQC
c i u true hinh hgc da tdi uu hda cua he chit phan img, hgp chit trung gian (IS) va trang thai chuyln tilp (TS) dugc bieu dien d hinh 3.
TSO/1 TSl/2
^„
6M..
TS2/P4
•2 342
1.337/J^1468i.2ia
^ 1 .
123-81
aj34,
121 19
(6, k. (b 4/
1.123 1.691. ^' 123 39 - ^ 7 14i57s
g
TS10/P8 TS8/P9
Hinh 3: Cau triic chit trung gian, tr?ng thai chuyen tiep ciia he phan ling C3H3 + H2O m dai hen ket (A), goc lien ket (°), dau c h t o thay cho dju phay chi phin thap phan]
TCHH, T. 53(1), 2015 (Tiip theo hmh 3)
Trdn Him Himg va cgng sif
TS8/PS
TSO/7 TS0/P7
1.241" "ft f.l.^^S 1275' COI
I
^ , 1 .wioa
loeT^r^
1 . 0 6 2 ^ 07.44 2.551
10.965 0.961
^ 1.416 ©jlf'
Hinh 3: Cau trie chat trung gian, trang thai chuyen tiep cua h$ phan img C3H3 + H2O [DQ dai lien ket (A), gdc lien kit (°), dau chim thay cho diu phay chi phin th$p phan]
TCHH, T. 53(1), 2015 (Tiep theo hinh 3}
Nghien ciru ly thuyet phdn img ciia gdc...
Hmh 3: Cau diic chat trung gian, trang thai chuyln tiep ciia he phan ling C,H3 + H2O [Dp dai lien ket (A), goc lien kSt (°), dau chim thay cho diu phay chi phin dijp phan]
3.3. Be mat the nang va cac thdng 56 nhiet d9Dg Tren bS mjt the nang cua he C3H3 va H2O (hinh 4), he chit tham gia phan ung ban diu dugc ki hi?u la RA, cac san phim ki hieu la P„ cac h(?p chit trung gian du(rc ki hieu la IS,, cac ttang thai chuyjn tijp dugc ki hieu la i/j. TCr kit qua tinh nang lugng dao dpng diem khong va nang lupng diim don xac djnh dugc cac muc nang lugng tugn^ quan ciia cac ciu tnic so vgi nang lugng ciia h$ chit ban diu tham gia phan ung C3H3 -f H2O (RA) dugc c)uy u6c bing 0.
Tir be mat the nang ta nhan thay, hai con duong qua TS0/P6 va TS0/P7 dugc hinh thanh do goc C3H3 tach lay hidro ciia phan tu nugc hinh thanh san pham P6 (CH2=C=CH2 -f OH) co nang luong tuong doi la 25,0 kcal/mol va P7 (CH<:-CH3 + OH) co nangjugng tugng doi la 28,9 kcal/mol thi san phim P6 de dugc hinh dianh hon do co nang lugng tugng
doi thap hgn va di qua phurc chit trung gian ban diu COI CO nang lugng rit thip la -0,8 Kcal/mol.
San phim P8 (CH2=C=CH0H-1-H) va P9(HOCH2CCH + H) dugc hinh thanh do g6c C3H3 lay OH Clia phan tu nugc qua TS0/P8 co hang rao nang lugng tugng d6i la 52,8 kcal/mol va 56,8 kcal/mol. Trong hai san phim nay thi san phim P8 de dugc hinh thanh hon do TS0/P8 co nang lugng tuong d6i thip hon TS0/P9 va san phim P8 co nSng lugng tugng ddi la 38,5 kcal/mol thip hon san phim P9 CO nang lugng tuong d6i la 43,7 kcal/mol.
Co che cOng H-OH vao vao cacbon Cl va C3 Clia goc C3H3_ qua cac TSO/8 (-l-65,l kcal/mol) tao thanh hgp chit trung gian IS8 (-1-8,5 kcal/mol), r6i qua cac TS8/P9; TS8/P10, TS8/P5 va TS8/P11 thi con dugng qua TS8/P5 c6 nang lugng tugng doi thap nhat nen v i mat dpng hgc thi thii tu san phim u u t i e n l a P 5 > P 9 > P 1 0 > p n .
TCHH, T. 53(1), 2015
Trong cac con ducmg cgng H-OH vao cacbon C2 va Cl cua g6c CjH3 qua TSO/4 (-f51,4 kcal/mol);
vao cacbon C2 va C3 ciia goc C3H3 qua TS0/l(-l-52,5 kcal/mol); vao cacbon Cl va C2 ciia goc C3H3 qua TS0/7(-t-54,6 kcal/mol); thi con dugng qua TS0/4-. IS4 -> TS4/5 -> 1S5 - • TS5/P2 tao ra san phim P2 (CHj + CH2CO) la d l hinh thanh nhit vi mat dpng hpc do TSO/4 co nang lugng tucmg dii
Trdn Hihi Himg va cong su thip nhit. Con duong qua TSO/1 va TSO/7 hinh thanh nen cac san phim P l (C2H5 + CO) (-20,2 kcal/mol); P3(C2H, -I- HCO) (-3,73 kal/mol); va P4 (CH2=CHCH0 -I- H) (13,8 kcal/mol) thi t h i tu uu t i e n P 3 > P l > P 4 .
Cac thong s6 nhiet dpng hpc ciia cac^ duong phan ling dugc tinh bang phuang phap phiem ham mat dp va gia tri ciia chiing dugc trinh bay a bang 2.
E(kcaI/mol)
51,4
• 0/4 ' ;
, 54,6 .'O/T.
,' . 29.7 '
;8'i?;'-'
'"•fv'r/2--i"
'i'^:'«,8/
.','ISrf '
••Bfi
'••^f-'x'
91,4
•'SBTti--.
; 85.5
56,8
' om"
IS4 CH2C(OH)Cif2 IS3
CHjCOCH, 1S7 CH2CHCHOH
/ ,---/':J^-, /A"- ....i'.'{'.'l!fe.V':';:::::: -'*•--
' ' , ' ' / y 36,8 5,.X .'MV ''^\!
sio'-' ; /'• .'' / a . ..'•""rv-.,-'- / • , / ™ " -
; , • ' , ' ' ', / - • • ; , - «
;.•/ ' 3 ? ' ; •.iin'-- 1S6 '. ; I;/ CHjCHiCHO '.,ai
IS2 IS3 CHjCHCHO CHjCHjCO
:--Si?p!>
->-is.SP8
- . . ^ 1 P7
-ii%6 - • a ? P 5
= •-—i P4
- - - • a P2 -. -20,2
•^ Pl
Hinh 4: Be mat the nang cua h? phan ung giira C3H3 vdi H2O
Bdng 2: Gia trj nang lugng cac thdng sd nhiet ddng hgc cua he C3H3 vdi H2O d 298 K, latm Dugng phan irng
Pl(C2H5-fCO) P2(CH3 -I- CH2CO) P3 (C2H4 + HCO) P4 (CH2=CHCHO + H) P5(C2H2 + CH2OH) P6 (CH2=C=CH! -^ OH) P7 (CH3CCH3 + OH) P8 (CH2=C=CH0H+H) P9 (HOCH2CCH -1- H) PIO (CHCHCHO+ H2) P l l (CHCHCHOH+ H)
AG°(kJ/mol) -87,86 -24,35 -18,42 -f71,48 -1-106,34 -1-114,47 -1-123,62 -1-173,41 -H95,21 -1-346,49 -f358,62
AS°(J/mol.K) -l-6,04 +3,69 +0,81 -55,09 -1,53 15,85 -13,82 -46,30 -47,90 -26,53 -51,71
AH°(kJ/mol) -86,05 -23,58 -18,17 +55,04 +105,88 +109,74 +119,49 +159,60 +180,92 +338,57 +343,19
AH"(kJ/mol) (Thuc nghiem) [13]
-88,6± 2
+112±2 +122±4 +127 ± 3
TCHH, T. 53(0,2015
Ket qua tinh d bang 2 cho thay ve m|t nhiet dpng hgc thi cac phan ung hinh thanh san pham theo thu tu uu tien: Pl > P2 > P3 > P4 > P5 > P6 > P7 >
P8 > P9> PIO > Pl 1. Qua so sanh chiing tdi thiy kit qua ti'nh toan AHjgg cua 4 dudng phan ung Pl, P5, P6 va P7 kha sat thuc nghiem. Tir do cd the ket luan nhiJng ket qua tinh toan theo ly thuyet sii dyng phuong phap B3LYP vdi bd ham aug-cc-pvtz la dang tin cay.
4. KET LUAN
Da toi uu hda dugc cac cac cau tnic hinh hgc ciia chit phan ung, hgp chat trung gian, tr^ng thai chuyen tiep va cac chat san phim cua he phan irng C3H3 vdi H2O bang phuong phap phiem ham mat do B3LYP vdi bp ham aug-cc-pvtz. Da thiit lap dugc be mat the nang, giai thich co che phan ung ciia he va tinh toan dugc cac thdng sd nhi?t dgng cua 11 san phim. Tu dd cho thiy 11 san phim diu cd the dugc t^o thanh trong dd san phim P6 (CH2=C=CH2 + OH) di qua phiic chit trung gian COI la de dugc tao thanh nhit vl mat nang lugng.
TAI LIEU THAM KHAO
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Nghien ciru ly thuyet phdn ung cua gdc....
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Pople. Gaussian, Inc, Pittsburgh PA, (2003).
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Lien A?: Tran Hiru Hung
Bg mdn Hoa, Jrudng D?i hgc Kiln tnic Ha Ngi Km 10, Nguyin Trai, Thanh Xuan, Ha Ngi E-mail: [email protected].
