2D 02	  Theoretical	  Study	  of	  Glucose	  Hydrolysis	  Mechanisms	  	  using	  RISM-­‐SCF-­‐SEDD	  	  (Nagoya	  Univ,	  Institute	  of	  Transformative	  Bio-­‐Molecules)	  ○Arifin,	  D.	  Yokogawa,	  and	  S.	  Irle	  [Introduction]	   	   	   	   	   The	   aim	   of	   this	   study	   is	   to	   investigate	   the	   important	   factors	   of	   glucose	  hydrolysis	   into	   5-­‐hydroxymethylfurfural	   (HMF),	   in	   order	   to	   increase	   and	   develop	   the	  production	   ways	   and	   utilizations	   of	   this	   reaction.	   Many	   computational	   and	   experimental	  studies	   have	   been	   conducted	   to	   learn	   about	   this	   reaction,	   but	   we	   still	   lack	   a	   detailed	  understanding	  about	  how	  the	  chemical	  reactions	  proceed.	  	  	  Previously	   proposed	   mechanisms	  for	   conversion	   of	   glucose	   into	  HMF,	   as	   giving	   in	   Scheme	   1,	  suggest	   that	   glucose	   needs	   to	   be	  first	   transformed	   into	   fructose	   (B)	  whereas	  fructose	  directly	  converts	  into	   HMF	   (A)	   [1].	   These	  mechanisms	   were	   suggested	   on	  the	   basis	   of	   reactions	   in	  alkylimidazolium	   chloride	   ionic	   Scheme	  1.	  Previously	  proposed	  mechanisms	  via	  open	  ring	  [1]	  liquids,	   such	   as	   [BMIM]Cl	   and	  [EMIM]Cl.	   	   Before	   modeling	   the	  reactions	  in	  ionic	  liquids,	  however,	  we	  decided	  to	  first	  investigate	  the	  reaction	  mechanisms	  in	  acidic	  aqueous	  environments.	  
Besides	  the	  open	  ring	  mechanism,	  cyclic	  or	  closed	  ring	  mechanisms	  have	  been	  proposed	  by	  experimental	   and	   theoretical	   works	   [2]	   as	   the	   reaction	   pathways	   of	   glucose	   isomerization	  into	   fructose.	   In	   the	   present	   work,	   we	   consider	   both	   cyclic	   (Scheme	   2)	   and	   open	   ring	  mechanism	  and	  further	  dehydration	  of	  fructose	  into	  HMF.	  	  	  	  

OHOHO

OHHO

OHHO- H 2O

OOHydrate- HOshiftHO

OH2HO

OH7+ H 2O- H 3O+- H 3O+	  + H 2OHOHOO	  	  H6+ H 2O	  OHHOOH2OHβ-glucose (1)HH- H 2O HOOHOH	  HO+ H 3O+O+ H 2OHOOHOHO1312

OHHHO

HO10

8 OHOH+ H 2O - H 3O+HO- H 2OHOOH2 OH
HO- 2 H 2O- H 3O+HO+ H 3O+OHOOOOH OHHHO	  HO

OHβ-fructose (9)HMFScheme	  2.	  Proposed	  cyclic	  m echanisms	  	  [Computational	   Details]	  	  	  	  	  	  To	  tackle	  the	  complexities	  of	  the	  reaction	  paths,	  originating	  from	  the	   solvent	   effect,	   we	   applied	   RISM-­‐SCF-­‐SEDD	   [3]	   as	   the	   solvation	   theory	   in	   combination	  with	   DFT	   and	   coupled-­‐cluster	   electronic	   structure	   methods.	   RISM-­‐SCF-­‐SEDD	   method	   is	   a	  combination	  between	  statistical	  mechanics	  for	  molecular	  liquid	  and	  molecular	  orbital	  (MO)	  theory.	  All	  of	  the	  geometries	  were	  optimized	  with	  RISM-­‐SCF-­‐SEDD-­‐B3LYP/6-­‐31+G(d)	  level	  of	  theory.	   The	   energies	   were	   evaluated	   at	   RISM-­‐SCF-­‐SEDD-­‐CCSD(T)/aug-­‐cc-­‐pVDZ.	   All	  calculations	  were	  performed	  by	  a	  modified	  version	  of	  the	  GAMESS	  program	  package.	  
[Results	  and	  Discussions]	  	  	  	  	  Figure	  1	   shows	   the	   free	   energy	   surface	   of	  the	   glucose	   isomerization	   into	  fructose,	   via	   cyclic	   mechanism,	   at	  room	   condition	   (1	   atm,	   298.15	   K)	  and	   experimental	   condition	   (10	  MPa,	  473.15	  K).	  The	  free	  energy	  of	  activation	   (TS2-­‐3)	   for	   this	  mechanism	   are	   25.87	   kcal	   mol-­‐1	  and	   22.70	   kcal	   mol-­‐1,	   respectively	  for	   room	   and	   experimental	  condition.	  	  Free	   energy	   diagram	   for	   fructose	   Figure	  1.	  Free	  energy	  surface	  of	  glucose	  isomerization	  transformation	  into	  HMF	  is	  shown	  in	  Figure	  2.	  There	  are	  at	  least	  two	  possible	  reaction	  pathways	  involving	  different	  transition	  states.	  	  The	  free	  energy	  of	  those	  transition	  states	  were	  very	  close	  each	  other.	  	  	  	  	  	  	  	  	  	  	  Figure	  2.	  Free	  energy	  surface	  of	  fructose	  hydrolysis	  into	  HMF	  More	  details	  will	  be	  given	  in	  the	  oral	  presentation.	  
[References]	  [1]	  Binder,	  J.	  B.,	  Raines,	  R.	  T.	  J.	  Am.	  Chem.	  Soc.,	  131,	  1979,	  2009.	  
[2]	  Qian,	  X.,	  Wei,	  X.	  	  J.	  Phys.	  Chem.	  B,	  116,	  10898,	  2012.	  
[3]	  Yokogawa,	  D.,	  Sato,	  H.,	  Sakaki,	  S.	  J.	  Chem.	  Phys.,	  126,	  244504,	  2007.