Intramolecular Hydrogen bonding for Lattice fluid EOS J.H.Lee and C.S.Lee Chemical and Biological engineering in Korea Univ.
Scope Intramolecular Hydrogen bonding Models for intramolecular HB Proposed Model and model parameter Results Conclusion
Intramolecular Hydrogen Bond Intramolecular hydrogen bond A hydrogen bond formed between two functional groups of the same molecule Intramolecuar HB plays an important role in Protein folding
Intramolecular HB - Polymer Cloud-point pressure is decreased owing to intramolecular HB at polar solvents (Gregg et al, 994) Blank PIB Cloud point pressure Medium Monohydroxy PIB Large Dihydroxy PIB Small
Previous Work Ghonasgi(994) For intermolecular association, Wertheim s thoery For intramolecular association, Ghonasgi(994) s theory was used. X X A o ( X X o + ρx A ) X X 3 2 A intra o + ( ρ intra A inter inter AB ρ ρx intra X o int er o inter o + )( X + X A intra o ) 2 intra X o 2ρ inter X A 2 ρ ( inter ) 2 0
Previous Work Lattice HB Developed by Brinkley(998) and Missopolinou (999) Ω HB Ω intra Ω inter doner acceptor HB
Brinkley (998) Analysis of Intra- and Intermolecular HB of Glycolether using FTIR experiments. Inter : - Intramolecular Inter : -2 H-bond OH-OH H-bond OH-Ether One way of forming intramolecular HB for molecule ( Q intra )
Problem Brinkley s theory No consideration about distributing Intramolecular HB molecules among total molecules P P Q inter intra inter cm ρ N c B T ( N ( N B M B)!(3N B)! )!(3N B M )! M! B : Intramolecular HB pair M : Intermolecular HB pair c B : probability for ring formation Q HB QintraQinterPintra Pinter B M F exp( kt B )exp( F kt M )
Missopolinou (999) First formalisms for equation-of-state H-bond OH-OH H-bond OH-Ether Donor population Acceptor population Acceptor 2 population : - OH 2 : -O- Q HB B 2 2 ( N!) (2 N B)! cm ρ M ( ) ( cb ) BN!! N! N!( N N )!(2 N B N )! N 2 0 2 T B
Problem Missopolinou s model If sequence of numbering is reversed, partition function is different. Acceptor 2 population Donor population Acceptor population Q HB B! N! N 2 B 2 (2N )! N!( N B)!! N!( N N )!(2N 0 c ( )! NT M ρ B N 2 ) M ( c B ) B
This Work Correct formalism of Q intra and Q inter General intramolecular HB model for any molecules Assumption Number of distributing intermolecular molecules N B A2 Qintra () c exp( B ) ( N B)! B! kt CH 3 O CH 2 HO CH 2 CH 3 O CH 2 CH 2 OH HO CH 2 CH 2 O CH 3 A intra A ij (inter)
This Work 2-methoxy ethanol N B A2 Qintra () c exp( B ) ( N B)! B! kt Q inter ( N B)! N rh ( ) N! N!( N B N N )!( N N )! N! N 2 2 ( xn B)! r A A N N ( xn B N )! N! N kt kt Ethylene-glycol H N2 ( ) exp( ) 2 2 2 2 r r N HO CH 2 N B intra Qintra () c exp( B ) ( N B)! B! kt Q A (2 N B)! (2 N B)! r A N H N ( ) exp( ) inter N!(2 N B N)!(2 N B N) Nr kt HO CH 2
Result FTIR regression Hydrogen bonding parameter from 35 o C and 45 o C experiment data Pure parameter fitting VLE calculation Comparison with Intra HB and without Intra HB
FTIR regression 0.030 Mole Fraction Bonded 0.025 0.020 0.05 0.00 Intramolecular H-bonding Intermolecular H-bonding Model Col vs Col 5 0.005 0.000 0.00 0.0 0.02 0.03 0.04 0.05 0.06 2-Methoxyethanol Mole Fraction in n-hexane Fig.. Hydrogen bonding in 2-methoxy ethanol + hexane system at 35 o C
FTIR regression Mole Fraction Bonded 0.030 0.035 0.030 0.025 0.025 0.020 0.020 0.05 0.05 0.00 0.00 Intramolecular H-bonding Intermolecular Intramolecular H-bonding H-bonding Model Intermolecular H-bonding Model Col vs Col 5 0.005 0.005 0.000 0.00 0.0 0.02 0.03 0.04 0.05 0.06 2-Methoxyethanol Mole Fraction in n-hexane Fig. 2. Hydrogen bonding in 2-methoxy ethanol + hexane system at 45 o C
Model characteristics 0 N inter /N intra 0. 0.0 0.00 Gas phase Liquid phase 0.000 300 350 400 450 500 Temp(K) Fig. 3. Inter- and intramolecular hydrogen bond in 2-methoxy ethanol
Pure parameter fitting Regressed intramolecular parameter U HB S HB c Alcohol -4332-2.98 - Ether -2384-2.98-2-methoxyethanol - - 0.005 Pure parameter for 2-methoxy ethanol Inter only r A 7.000 r B 0.0038 r C -0.0024 e A 93.5 e B 0.75 e C 0.62 DP(% ) 4.04 D (%) 0.054 Intra + Inter 7.578 0.05-0.003 23.0-0.090-0.299.8 0.48 00 DP(%) N N i P P 00 ρ calc N calc i i Dρ(%) exp exp i N i ρi
Comparion : VLE calculation 0.6 0.40 0.35 0.5 0.30 0.4 P (bar) 0.25 0.20 0.5 Carmona et al(200) Inter Intra + Inter Col 5 vs Col 4 Col 8 vs Col 7 P (bar) 0.3 0.2 Carmona (200) Inter Intra + Inter Col 5 vs Col 4 Col 8 vs Col 7 0.0 0.05 0. 0.0 0.2 0.4 0.6 0.8.0 Mole fraction of n-hexane 0.0 0.2 0.4 0.6 0.8.0 Mole fraction of n-hexane Fig. 4. n-hexane + 2-methoxy ethanol at 40 o C and 50 o C
Comparion : VLE calculation 0.20 P (bar) 0.5 Carmona (200) Inter Intra + Inter Col 5 vs Col 4 Col 8 vs Col 7 0.0 0.05 0.0 0.2 0.4 0.6 0.8.0 Mole fraction of n-heptane Fig. 5. n-heptane + 2-methoxy ethanol at 50 o C
Comparion : VLE calculation 0.8 0.6 0.25 0.4 0.20 0.2 P (bar) 0.0 0.08 0.06 Carmona (200) Inter Intra + Inter Col 5 vs Col 4 Col 8 vs Col 7 P (bar) 0.5 0.0 Carmona (200) Inter Intra + Inter Col 5 vs Col 4 Col 8 vs Col 7 0.04 0.05 0.02 0.0 0.2 0.4 0.6 0.8.0 0.0 0.2 0.4 0.6 0.8.0 Mole fraction of Cyclohexane (a) Mole fraction of Cyclohexane (b) Fig. 6. n-cyclohexane + 2-methoxy ethanol at (a) 30 (b) 40 and (c) 50 o C
Comparion : VLE calculation 0.40 0.35 0.30 P (bar) 0.25 0.20 0.5 Carmona (200) Inter Intra + Inter Col 5 vs Col 4 Col 8 vs Col 7 0.0 0.05 0.0 0.2 0.4 0.6 0.8.0 Mole fraction of Cyclohexane (c)
Comparison DP(%) 2.62 4.8 323.5 3.69 5.77 33.5 4.96 6.20 303.5 Cyclohexane 2-methoxyethanol 8.09 5.40 323.5 n-heptane 2-methoxyethanol 5.2 6.0 323.5 5.08 7.23 33.5 n-hexane 2-methoxyethanol Intra and Intermolecular Intermolecular only Temp (K) System N i i calc i P P N DP exp 00 (%)
Conclusion Intramolecular hydrogen bonding based Lattice fluid statistics was proposed which considers the number of distributing molecules with intermolecular bonds Regressed Hydrogen bonding parameter and flexibility parameter showed consistent behavior of FTIR experiment data qualitatively and possibility for application to the equation of state. The models was found applicable to the calculation of VLE of alkane-2-methoxy ethanol in comparison with the model with only intermolecular HB