TAP CHi HOA HQC
DOI: 1015625/0866-7144.2014-0067
T. 52(6) 748-754 T H A N G 12 NAM 2014
NGHIEN CO'U LI THUYET CO CHt P H A N U'NG GIU'A G 6 C P R O P A R G Y L Vai PHAN TU' NITa OXIT BANG PHU'ONG PHAP PHI^M HAM MAT DO
Pham Van Tien'*, Le Kim Long^ Nguyen Thi Minh H u | ' ' Vien Ky thugt Hoa hgc, Tnrdng Dgi hgc Bdch khoa Hd Ndi
^Tnrdng Bgi hgc Gido due. Bgi hgc Qudc gia Hd Ndi
^Khoa Hod hgc, Tnrdng Bgi hgc Suphgm Ha Ngi DSn Tda soan 15-4-2014; Chip nhan dang 4-12-2014
Abstract
The reaction mechanism of the Propargyl radical and Nitrogen oxide has been studied by the Density Functional Theory (DFT) using the B3LYP fiinctional in conjunction with the 6-311++G(3df,2p) basis set. The potential energy surface (PES) for the C3H3 and NO system was also established. Calculated results indicate that products of this reaction may be (HCCCN+HjO), (CzH2+HCN0), (HCCCNO+H2), (HCN+H2CCO), (HNO+HiCCC), (HiCCCN+OH), (H2CCH+CNO), (H+HCCCHNO), (CN+H2CCOH), (C2H+H2CNO), (CH3+CCNO), (CH3+OCCN), (H2C+HCCNO), (H2CC0+HNC) and (CjH^+CNOH). However, the formation of (HCN+H2CCO) is the most favorable.
Keywords. Reaction mechanism, propargyl radical, nitrogen oxide, density functional theory.
1. MO DAU
Hoa hgc lugng tu" la mdt nganh khoa hgc irng dyng CO hgc lugng tir d6 giai quyet mdt sd vin d6 ciia Hoa hgc. Cy the nd cho phep tien hanh cac nghien ciiu ly thuyit vh cau tnic phan tii, tinh chit va kha nang phan img, giiip tien doan ve cac dudng phan ling cd the xay ra va hudng hinh thanh san pham uu tien [1]. Trong nhimg nam gan day, vdi su phat frien cua khoa hgc may tinh, cd thk tinh toan mgt each nhanh chdng nhirng phep tinh phirc tap, giiip cho vice phat trien cac phuong phap va cac phan mem hda hgc lugng tii. Viec tinh toan hda hgc lugng tir khdng nhifrig cho biet cac thdng tin ve cau tnic, CO ehe phan iing, nhiet ddng hgc...ma cdn cac thdng tin \h phd hdng ngoai, tii ngoai, phd UV-VIS (phd electron) ...[14]. Nhieu phan iing don gian cd the xac dinh dugc cac thdng sd bang thuc nghiem, tuy nhien cd nhieu phan img xay ra kha phuc tap, khd cd the xac dinh dugc cac thdng sd hay co clie phan ling bang thuc nghiem. Nhd vay cac phuong phap hoa hgc lugng tir trd thanh cdng cu die luc trong viec nghien ciiu, khao sat cac ciu tnic phan tu, CO ch6 ciia nhirng phan iing khac nhau. DiSu dd cho thay su can thiet ciia viec nghien ciru li thuy6t kk hgp vdi viec su dung cac phan mem tinh toan hda hgc lugng tu hien dai [14].
Hien nay vdi su phat triln nhanh chdng cua nganh cdng nghiep, chit lugng cude sdng ciia con
ngudi dugc nang cao rd r^t. Con ngudi ngay cang quan tam tdi nhirng tac nhan gay d nhilm m6i frudng, anh hudng tdi siic khde, dgc bi^t la qua trinh ddt chay nguyen hda thach. Ngudi ta phat hi^n trong qua trinh ddt chay nay hinh thanh cac hidrocacbon thom da vdng va mudi thi cd sy xuat hi^n ciia gdc propargyl (C3H3) [5]. Su hinh thanh gdc C3H3 nhu mgt san pham trung gian kem ben nhung l?i cd vai trd quan trgng, quyat djnh co chg phan img va san pham tao thanh. C3H3 la mgt gdc ty do cdn mgt electron ddc than nen cd kha nang phan iing cao, no cd the phan iing vdi nhiSu gdc ty do, nhidu phan tu trong mdi trudng khi quyen nhu: 0(^P), H2, O2, N2, CH4, NH3, H2O, C2H6, NO,, ...[5].
Thuc te thi hien nay gdc propargyl da va dang nhan dugc su quan tam Idn ciia cac nha hda hgc.
Tham khao cac cdng trinh da dugc cdng bd thi gdc nay da dugc nghien cihi frong phan img vdi 0 ( P), C3H3 [8]. Tuy vay, chua cd cdng frinh nao cdng bd v6 CO ehe phan iing ciia gdc C3H3 vdi phan tir NO.
De nghien ciru ve phan iing ciia gdc propargyl (C3H3) vdi cac hgp chit tdn tai trong khi quyen, chung tdi tien hanh khao sat co chd phan ling gifla goe propargyl vdi phan tir NO. Trong phan iing nay, he chit phan iing dugc dy doan bi6n doi theo hai nhdm phan iing: Chat phan irng (RA) -^ TS —> san phim (PR); Chit phan irng (RA) - . san phim trung gian (IS) -> san pham (PR). Tren co sd dd, chiing tdi se tien hanh cac tinh toan hda lugng tir d^ khao
TCHH.T. 52(6). 2014
sat va danh gia kha nang phan irng cung nhu du doan cac san phim cd thi thu dugc frong h? phan ling C3H3 + NO.
2. PHUONG P H A P T I N H
Cau tnic hinh hgc ciia cac chat [jhan umg, cac chit frung gian, frang thai chuyin tiip va cac san phim diu dugc tdi uu theo phuong phap phi8m ham mat dg d mire B3LYP/6-311++G(3df,2p) [14].
Trong dd fr^g thai chuyen tiep diing dugc xac thyc bing vi?c phan tich tin so dao ddng, tga dg thuc (IRC) ciia phan irng. Ngoai ra do nhilm spin (S^) cung dugc xem xet. Nang lugng diem dcm va nang lugng dao dgng diem khdng dugc tinh 0 miic
Phgm Vdn Tiin vd cgng s{r
B3LYP/6-311++G(3df,2p) [14]. Tir cac kit qua nhan dugc se xac dinh ciu tnic, nang lugng, cac thdng sd nhi?t dgng va thilt l^p be mat the nang cua h?. Cac tinh toan dugc thuc hi^n fren phan mim Gaussian 03 [15].
3. KET QUA VA T H A O LUAN 3.1. Dir doan kha nang phan ung
D I SO bd dy doan hudng phan iing uu tien frong h? C3H3 va NO, chiing tdi da tinh va phan tich nang lugng ciia cac obitan phan tir (MO), mgt so kit qua dugc dua ra d bang 1.
Bdng I: Gia tri nang lugng ciia HOMO va LUMO d B3LYP/6-311-H-G(3df,2p)
Q H j
NO
E (HOMO) (eV) -0,22287 (HOMOa) -0,28559 (HOMOP) -0,22510 (HOMOa-pi) -0,47272 (HOMOP)
E (LUMO) (eV) -0,00369 (LUMOa) -0,10470 (LUMOP) -0,11511 (LUMOa-sg) -0,10008 (LUMOP)
AE(LUMO-HOMO) (eV) CjHj(a)-NO(a) C3H3(a)-NO(P) C3H3(P)-NO(a) C3H3(P)-NO(P) NO(a) - C3H3(a) NO(a)-C3H3(P) NO(P)-C3H3(a) NO(P)-C3H3(P)
0,22141 0,46903 0,1204 0,36802 0,33798 0,4007 0,12279 0,18551
Ap dyng li thuyet obitan phan tir bien FMO (frontier molecular orbital) [14] va kit qua tinh 0 bang cho thiy, gia fri AE nhd nhit img vdi miic nang lugng LUMOp ciia gdc C3H3 va HOMOa ciia NO.
Do dd, khi phan iing xay ra thi mat dg elecfron se dich chuyen tii NO sang gdc C3H3 de bao hda frang thai hda tri. Ket qua nay hoan toan phii hgp vdi kha
C3H3 HOMO
nang hinh thanh Hen ket xich ma trong sy hinh thanh cac san phim quan trgng nhit ciia phan iing frong h?
nay. Hinh anh cac obitan bien dugc bieu dien 0 hinh 1.
Cac hudng phan iing cd the xay ra cQa he phan irng gi&a C3H3 vdi NO dugc minh hga chi tiet trong SO do hinh 2.
NO
Hinh I: Hinh anh cac HOMO va LUMO cua C3H3 va NO
749
TCHH, T. 52(6), 2014 Nghien cuu li thuyit ca chi...
- • HjC=C-CH-NO * — • H C = C H - C H N O — 2 i - . - C j H j + H C N 0 PRj
- H,OC-C-NH0 H2CM>C + HNp PR, H;C-CH-C-NO " " » H,C-CC-NO 1 >- CHj + CCNO PR,,
- 1 ^ - * - HCCCNCKH; PR, H^CCH + CNO PR,
I ° ' . HC=CH-C-NOH '^—^ C;H; + HNOH PR,, -H2C=C=C=N0H .>H;CCCN + 01) PR*
HjCCH + CNO PR, HjC-CH-CNO -
' HCCCN+ H2O PR,
H,C=C-CN- - H2CCQH + CH PR5
H,C + HCCNO PR,,
HCC-CH2-NO -
^ 2 - ^ HC=CH-CHNO
*^ HCCCHNO + H PRg
»• CjH + H,CNO PR 10
- HCN + H2CCO PR,^
--- H-,C-C-CN - 1 "
hi o
- * - CH3 + OCCN PR|2
- * - H2CCO + CNH PR|4
- HCC-CH=NOH-
I4 - HCCCN + H2O PR,
Hmh 2: So dd chi tiet co ehe phan ung gifla C3H3 vdi NO
3.2. Cau true hinh hgc va be m | t the nang Cau true hinh hgc da toi uu hda cita he chat phan ling, hgp chit trung gian (IS) va t r ^ g thai chuyin tiep (TS) dugc bleu dien dhinh 3.
Be mat the nang bieu dien nang lugng tuong ddi ciia cac chat phan irng (RA), tr^ng thai chuyin tilp (TS), cac chat frung gian (IS) va cac san pham (PR) dugc dua ra d hinh 4.
Tfl be mat the nang ta nhan thay: hai san pham frung gian ISl va IS3, cd nang lugng tuong ddi la -28,24 kcal/mol va -18,52 kcal/mol, deu dl dang dugc hinh thanh do C3H3 va NO la hai chat diu cd 1 electron dgc than nen cd nang lugng boat hoa cao.
San pham de hinh thanh nhat, san pham P6 (H2CCCN + OH), dugc tao ra thdng qua con dudng di qua frang thai chuyin tiep TSl cd nang lugng tuong ddi tuong iing la 24,77 kcal/mol. Tuy nang lugng nay cao hgn so vdi h? chit phan iing, nhung so vdi cac san pham phan img khac, thi P6 la san pham thu^n Igi nhit ve mat nang lugng.
San phim P5 (HNO + HjCCC) khd hinh thanh nhit vi cd nang lugng la 148,5 kcal/mol, cao hon rit nhilu so vdi hg chit RA. San phim nay dugc hinh thanh thdng qua cac san phim trung gian ISl, IS6,
IS7, ISID va cac trang thai chuyen ti6p TS5, TSll va TSl2 cd nang lugng tuong doi iin lugt bing 21,69 kcal/mol, 17,08 kcal/mol ya 42,17 kcal/mol.
Trong dd, TSI2 cd nang lugng rit cao, nen tir IS 10 rat khd vugt qua hang rao nang lugng nay de tao ra san phamPS.
San pham PI (HCCCN+H2O) cd thi dugc t?o thanh tii 2 dudng khac nhau, dudng thii nhit di qua cac frang thai chuyen tiep TS2 va TS7 cd nang lugng tuong irng la 34,24 kcal/mol va 19,37 kcal/mol; dudng thir hai di qua cac trang thai chuyen tiep TSl va TS6 cd nang lugng tuong img la 24,77 kcal/mol va 30,86 kcal/mol. Nhu vay, san pham PI di theo dudng thii nhit thuan Igi hon ve mat nang lugng so vdi dudng thii hai.
Tir ISl qua t r ^ g thai chuyin tiep TS5 (21,69 kcal/mol) va frang thai trung gian IS6 (1,37 kcal/mol) cd thi tao ra san phim P7 (H2CCH + CNO). Tuy nhien, tir ISl cung cd the di qua tr?ng thai chuyin tiep TS24 (24,87 kcal/mol) va frang thai trung gian IS8 (1,03 kcal/mol) dl t?o thanh san phim P7. Nhu v^iy, frong hai con dudng tao thanh san pham P7, con dudng thii nhat t h u ^ Igl hon vl m^t nang lugng.
Ca hai san phim P4 (HCN -H HjCCO) va PI2
TCHH.T 52(6), 2014 Phgm Vdn Tien vd cgng su
Vr 123C
117.7-^^21.13
•fl.062
122.46 l - 2 6 7 i ( 0 ^ ' r ' ^ ) 115.97 1 = ' « ' ® 1.686'
TS3
TS5 1.2801.371 '";¥X 126,93
i.2!«^SriJl6rrni5»^
174 82
^ . ^
7S7
_^ 1.2«.«,U9. „ „
^
11.539 1 . 1 ' ' 155.S3
TSIS
^ 1 0 6 6
163.50^ V ^
Hinh 3
751
TCHH, T. 52(6), 2014 Nghien cm li thuyet ca chi...
Hinh 3: Cau true chat trung gian, tran^ thai chuyen tiep cua he phan ling C3H3 + NO [Bp dai lien ket (A), goe lien ket (°), dau chSm thay cho dSu phay chi phjn thap phan]
TCH( '.52(6), 2014
CH3 + OCCN) diu dugc hinh thanh tii san pihim trung gian IS9. Nlu xet vl nang lugng tuong ddi thi
Nghien ciru li thuyit ca chi...
san pham P12 thuan Igi hon, tuy nhien, san pham P4 lai ben hon.
HC-<Mjls-CiH'l7.(13
H j c ^ . c i J 5 S ) > - ^ ' ,
' ^ C H ^ C H O F U ,11
^ CjH*BjCSO PIO 92
^ H ^ H C C C T O I O P i
— KjCCOt-HNCPH .2
^ t ^ ' - t n c c o H p»
^ H ^ C O ( > O H P4
i " C^Hj-HCNO Pi
—HCCCNCKH] Pj
™ C H j . O C C N P12
I S » H 3 0 C ( O H > C N « I , 1 ) • H l C - C C O K K H t O . D E i l ISlTHjCCffi)CNf0.1)
FTmh 4: B I mat thi nang cua he phan iing gifla C3H3 vdi NO
Cac thdng so nhiet dgng hgc ciia cac dudng phan umg dugc tinh bing phuong phap phiem ham m^t dg va gia frj cua chiing dugc frinh bay d bang 2.
Bdng 2: Gia tri nang lugng cac thdng sd nhi?t ddng hgc cua he C3H3 vol NO
Duong phan ung Pi (HCCCN + H2O) P2 (CiHz + HCNO) P3 (HCCCNO + H2) P< (HCN + H2CCO) Pi (HNO + H2CCC) P» (H2CCCN + OH)
PT ( H J C C H + CNO)
P. ( H + HCCCHNO) P9 (CN + H2CCOH) Pio(C2H-l-H2CNO) P„ (CH, + CCNO) P„ (CH, + OCCN) P,3 (H2C + HCCNO) P,j (H2C + HCCNO) P„ ( C H , + CNOH)
AG", kJ/mcl -57,38
-6,55 -3,28 -72,11 129,19 0,43 95,98 38,10 27,56 59,54 62,30 -19,61,4
72,44 28,51 72,80
AS°,J/mol.K -4,27 -3,74 -17,69 -2,12
1,22 0,76 5,70 -8,66 0,97 -7,52 4,80 4,62 2,87 3,13 0,61
AH°, kJ/mol -58,65
-7,67 -8,55 -72,74 128,83 0,65 97,68 35,52 27,84 57,30 63,73 -18,23 73,29 29,44 72,98
AH°, kJ/mol (Thuc nghi$m) [16]
-60,5 ± 2 -8,6±1 -70,52 ±2
-20,97±2
T C H H , T. 52(6), 2 0 1 4
K i t qua tinh d b a n g 2 c h o t h i y v l m | t nhiet dgng hgc thi cac phan img d tren deu cd kha n a n g xay ra. Thir t u uu tien n h u sau: P4 > P I > P12 > P2
> P 3 > P 6 > P 9 > P 1 4 > P 8 > P 1 0 > P 1 1 > P15 >
P13 > P 7 > P 5 . Q u a so sanh chiing tdi t h i y k i t q u a tinh toan AH^^g ciia 4 d u d n g phan umg Pi, P2, P4 v a Pi2 kha sat t h y c nghi?m. Tir do cd t h i k i t lu§n nhung k i t q u a tinh toan t h e o ly thuyet thu d u g c la dang tin cay.
4. K E T L U A N
Ap dyng p h u o n g p h a p phiem ham m a t d^ c h u n g tdi da tdi uu hda d u g c cac cau friic hinh hgc ciia chat phan ling, h g p chat trung gian, trang thai chuyen tiep va san pham cua h? phan iing g i u a C3H3 vdi N O . Da thilt lap dugc b l mat the nang va giai thich c o ehe phan img ciia h$ va tfl dd cho thay frong sd 15 nhdm san pham tfl PI den P15, cd 5 nhdm san pham tfl PI den P4 va P12 cd the de dang d u g c t^o thanh. Ve mat nhi?t dgng hgc, frong 15 nhdm san pham ciia h? phan irng, san pham P6 d l hinh thanh nhat va san pham P15 khd hinh thanh nhat. Ket qua nghien c u u nay cd t h i lam tai lieu tham khao cho cac n h a h d a hgc t h u c nghifm ho§c lam d i u vao cho c a c tinh toan li t h u y l t ve sau.
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Lien h?: P h a m V a n Tien Vi?n Ky thuat H d a hgc T r u d n g Dgi hgc Bach k h o a H a N g i Sd 1, Dgi Cd Viet, Hai B a T r u n g , H a N g i E-mail: t i e n . p h a m v a n @ h u s t . e d u . v n .
