PMID- 17014147
OWN - NLM
STAT- PubMed-not-MEDLINE
DCOM- 20070906
LR  - 20061003
IS  - 0743-7463 (Print)
IS  - 0743-7463 (Linking)
VI  - 22
IP  - 21
DP  - 2006 Oct 10
TI  - Degradation of the pesticide fenitrothion as mediated by cationic surfactants and 
      alpha-nucleophilic reagents.
PG  - 9009-17
AB  - The reaction of fenitrothion with a series of alpha-nucleophile oximates having 
      pK(a) values in the range of 7.7-11.8 was studied both in the absence and 
      presence of cetyltrimethylammonium (CTA(+)) surfactants. Reaction with 
      CTA-oximates was found to proceed through two pathways: S(N)2(P) and S(N)2(C); an 
      S(N)Ar pathway was not observed. Accordingly, the observed rate constants were 
      dissected into the two corresponding S(N)2(P) and S(N)2(C) pathways. Use of the 
      pseudophase ion exchange (PPIE) model for micellar catalysis in the CTA(+) system 
      allowed evaluation of micellar second-order rate constant (k(2m)) parameters and 
      binding constants, (K(S)). K(S) values for CTA-oximates were found to vary with 
      the counterion, and the rate enhancement depended on a combination of K(S) and 
      k(2m) values. k(2m)/k(2w) values ranged from 0.0025 to 0.64, suggesting that a 
      concentration effect is mainly responsible for the rate enhancement. In the 
      absence of surfactant, an alpha-effect (i.e., k(alpha)/k(normal)) varying from 8 
      to 450 was observed for the oximate reaction, decreasing with increasing pK(a). 
      It is proposed that differential solvation (transition-state imbalance) is a 
      cause of the alpha-effect in this system.
FAU - Han, Xiumei
AU  - Han X
AD  - Department of Chemistry, Queen's University, Kingston, ON, Canada K7L 3N6.
FAU - Balakrishnan, Vimal K
AU  - Balakrishnan VK
FAU - VanLoon, Gary W
AU  - VanLoon GW
FAU - Buncel, Erwin
AU  - Buncel E
LA  - eng
PT  - Journal Article
PL  - United States
TA  - Langmuir
JT  - Langmuir : the ACS journal of surfaces and colloids
JID - 9882736
EDAT- 2006/10/04 09:00
MHDA- 2006/10/04 09:01
CRDT- 2006/10/04 09:00
PHST- 2006/10/04 09:00 [pubmed]
PHST- 2006/10/04 09:01 [medline]
PHST- 2006/10/04 09:00 [entrez]
AID - 10.1021/la060641t [doi]
PST - ppublish
SO  - Langmuir. 2006 Oct 10;22(21):9009-17. doi: 10.1021/la060641t.