Mechanism of BZ reaction
¡Ò÷ӤÇÒÁà¢éÒã¨
dynamical system ¢Í§»¯Ô¡ÔÃÔÂÒ
BZ ¨Óà»ç¹µéͧà¢éÒ㨷ÕèÁҢͧÊÁ¡Ò÷Õè¡Ó˹´
reaction kinetic ¢Í§»¯Ô¡ÔÃÔÂÒÍѹ¡Ó˹´â´Â
mechanism ¢Í§ overall BZ reaction «Öè§à»ç¹¾×é¹°Ò¹·ÕèÊÓ¤Ñ
â´Â mechanism ¢Í§»¯Ô¡ÔÃÔÂÒ
BZ ¹Õé¾Ñ²¹Òâ´Â
Field-Koros-Noyes(FKN) ·ÕèÁËÒÇÔ·ÂÒÅÑÂ
Oregon àÃÒ¨Ö§àÃÕ¡
mechanism ¢Í§ BZ ¹ÕéÇèÒ
Oregonator model ËÃ×Í FKN model â´Â¨Ð¹ÔÂÁ
Oregonator ÁÒ¡¡ÇèÒ à¾ÃÒÐÁÕÃٻẺ·ÕèàËÁÒÐÊÁ¡ÇèÒ
â´Âã¹»¯Ô¡ÔÃÔÂÒÃÇÁ¨Ð¾ºÇèÒÁÕ
species µèÒ§æ ¹éÍÂÁÒ¡
áµè㹤ÇÒÁà»ç¹¨ÃÔ§áÅéÇÁÕ
species áÅÐ intermediate ÁÒ¡ÁÒÂËÅÒµÑÇ
ËÒ¡µéͧ¡ÒÃÈÖ¡ÉÒÅÐàÍÕ´àªÔÍèÒ¹ä´é·Õè
J. Am. Chem. Soc., 94, 1972, 8649 ¨ÐäÁè¼Ô´ËÇѧ
áµèã¹ homepage ¹Õé¨Ð͸ԺÒÂã¹ÀÒ¾ÃÇÁ·Õè¨ÐàËç¹ÀÒ¾ä´éªÑ´´éÇÂ
FKN model áÅШÐáÊ´§
mathematical derived ´éÇ Oregonator ·ÕèÊдǡ㹷ҧ¤³ÔµÈÒʵÃìÁÒ¡¡ÇèÒ
¨Ò¡ FKN model ·ÕèµÑ´àÍÒ»¯Ô¡ÔÃÔÂÒÂèÍ·ÕèäÁèÁռŵèÍ»¯Ô¡ÔÃÔÂÒÃÇÁÍÍ¡ä»
àËÅ×Íáµè»¯Ô¡ÔÃÔÂÒ·ÕèÊÓ¤Ñà·èÒ¹Ñé¹â´Âáºè§à»ç¹
Process µèÒ§ æ 3 ¢Ñé¹´éÇ¡ѹ
¤×Í Process A ·ÕèÁÕ¡ÒáӨѴ
[Br-] ÍÍ¡, Process B ·ÕèÁÕ
Autocatalysis ¢Í§ HBrO2 à¡Ô´¢Öé¹
áÅÐã¹ Process C ·ÕèÁÕ¡ÒÃÊÃéÒ§
[Br-] ¡ÅѺÁÒÍÕ¡¤ÃÑé§
ä´é´Ñ§¹Õé
¢Ñé¹ÊÓ¤Ñã¹
Process A
(FKN3) BrO3-
+ Br- + 2H+ --> HBrO2 + HOBr
â´ÂÁÕ rate = k3[BrO3-][Br-][H+]2
(FKN2) HBrO2 + Br-
+ H+ --> HOBr
â´ÂÁÕ rate = k2[HBrO2][Br-][H+]
Process A :
BrO3- + 2Br- + 3H+ -->
3HOBr
¨Ò¡»¯Ô¡ÔÃÔÂÒ¢éÒ§º¹ã¹
process A ¾ºÇèÒ bromide ion ¨Ð¶Ù¡¡Ó¨Ñ´ÍÂèÒ§ÃÇ´àÃçÇä»à»ç¹
HOBr «Ö觨ÐÁÕ¼Åâ´ÂµÃ§µèÍ
process C àÁ×èÍ bromide ion Ŵŧ¶Ö§¨Ø´Ë¹Öè§áÅéÇ»¯Ô¡ÔÃÔÂÒ¨Ð
shift ä»ÂѧÍÕ¡ species
¹Ñ蹤×Í HBrO2 ·Õè¨Ðà»ÅÕè¹ä»à»ç¹
HOBr ´éÇ FKN2 «Ö觨ش¹Õè¨Ðà»ç¹¨Ø´àÃÔèÁ
Process B ·Õèà»ç¹
Process B
(FKN5) BrO3-
+ HBrO2 + H+ <--> 2BrO2í
+ H2 â´ÂÁÕ rate = k5[BrO3-][HBrO2
][H+] - k5[HBrO2í]
(FKN6) BrO2í
+ Mred + H+ --> HBrO2 + Mox
â´ÂÁÕ rate = k6[BrO2í
][Mred][H+]
Process B : BrO3-
+ HBrO2 + 2Mred + 3H+
--> 2HBrO2 + 2Mox + H2O
â´ÂàÁ×è;ԨÒóһ¯Ô¡ÔÃÔÂÒ
FKN-5(»¯Ô¡ÔÃÔÂÒÂé͹¡ÅѺ¢Í§
FKN5) áÅéÇá·º¨ÐäÁèà¡Ô´¢Öé¹
·ÓãËéä´é BrO2í
à¡Ô´¢Öé¹à»ç¹
balance ÃÐËÇèÒ§ FKN5 áÅÐ
FKN6 àÁ×è;ԨÒóÒ
Process B ÃÇÁ ¨Ðà»ç¹¡ÒÃà¾ÔèÁ»ÃÔÁÒ³µÑÇàͧ¢Í§HBrO2
·ÕèàÃÕ¡ÇèÒ
Autocatalysis ¢Í§ HBrO2 «Öè§¡ÒÃà¡Ô´
HBrO2 ¢Ö鹡Ѻ FKN5 «Öè§à»ç¹¼ÅãËéÁÕ
[HBrO2] à¾ÔèÁ¢Öé¹
áµèÍÂèÒ§äáç´Õ¡ÒÃà¾ÔèÁ¢Í§
HBrO2 ¶Ù¡¤Çº¤ØÁâ´Â
self-disproportionation reaction ¢Í§ HBrO2 ¹Ñè¹àͧ
(FKN4) 2HBrO2 --> BrO3-
+ HOBr + H+
â´ÂÁÕ rate = k4[HBrO2]2
«Öè§¡ÒÃà»ÅÕè¹
Process ¨Ò¡ A ä» B à¡Ô´¢Öé¹àÁ×èÍ
rate ã¹ FKN5 à¡×ͺà·èҡѹ¡Ñº
FKN2 áÅéÇËÒ [Br-] ·ÕèàÃÔèÁà¡Ô´
Autocatalysis ã¹ process B ´Ñ§¹Ñé¹
HBrO2 áÊ´§µÑÇà»ç¹
inhibitor ¢Í§ Br- ¹Ñè¹àͧ
áÅÐã¹ FKN4 ·Õè·ÓãËé
[Br-] Ŵŧä»ÍÕ¡àÁ×èÍà¡Ô´
autocatalysis à¾ÃÒÐÁÕ¡ÒÃÊѧà¤ÃÒÐËì
BrO3- ¢Öé¹ áÅÐàÁ×èÍ
[Br-] ŴŧÁÒ¨¹¶Ö§
critical bromide ion concentration «Öè§à·èҡѺ
k2[HBrO2][Br-][H+]
= k5[BrO3-][HBrO2
][H+]
[Br-]cr = (k5/k2)[BrO3-]
= 1.4 x 10-5[BrO3-]
àÁ×èͶ֧ [Br-]cr
áÅéǨÐÁÕ¡ÒüèÒ¹¢Ñ鹵͹
Process B ä» C·ÕèÁÕ¡ÒÃà¡Ô´
autocatalytic acceleratory oxidation of metal ion catalyst ä´éá¡è
Process C : 2Mox
+ MA + BrMA --> fBr- + 2Mred + other product
·ÕèÁÕ rate = kc[Org][Mox]
àÁ×è;ԨÒóÒ
Process C BrMA( Bromomalonic acid ) ¹Ñé¹à¡Ô´¨Ò¡
HOBr ·Õèà¾ÔèÁ¢Ö鹨ҡ
process A áÅÐ Mox ·Õèä´é¨Ò¡
process B
â´Â·Ñé§
MA (malonic acid) áÅÐ BrMA (bromomalonic acid) ÅéǹáÅéÇáµè¨Ð·Ó»¯Ô¡ÔÃÔÂҡѺ
Mox ·Ñ駤Ùè áÅéÇä´é
Bromide ion ¡ÅѺ¤×¹
áµè¤èÒ
stoichiometric factor f ¢Í§ bromide ion
à»ç¹ parameter ·Õè adjust
¤èÒä´é ¶éÒ Mox
·Ó»¯Ô¡ÔÃÔÂÒ੾ÒСѺ
BrMA áÅéÇ f = 2, ËÒ¡
f > 2/3 áÅéÇ net concentration
¢Í§ Br- ¨Ðà¾ÔèÁ¢Öé¹·Ø¡Ãͺ¢Í§¡ÒÃ
oscillate ¹Í¡¨Ò¡¹Õé
f ÂѧÁÕ¤èÒä´éËÅÒ¤èÒµÒÁ
MA , BrMA, HOBr áÅÐÍÕ¡ËÅÒÂ
æ intermediate species áµèÍÂèÒ§äáçµÒÁ
rate ¢Í§ process C ¡ç¢Ö鹡Ѻ¤ÇÒÁà¢éÁ¢é¹¢Í§
Org species ¡çä´é «Öè§»ÃÐÁÒ³ä´éà·èҡѺ¤ÇÒÁà¢éÁ¢é¹àÃÔèÁµé¹¢Í§
MA ¹Ñè¹àͧ