IA data based, boiling point estimation for structural isomers using molecular weight, carbon chain and carbon fraction.

1. Which model is a better predictor, using molecular weight (MW) or number of carbon
chain (CC) or carbon fraction (CF) or (CF + MW) model for b/p prediction of structural
isomers with 6, 7, 8 carbons.
Is number carbon chains, molecular weight, carbon fraction a good predictor Independent variable
Dependent
variable
Data Handbook. Click here data
IA secondary data based – Simple regression analysis for boiling point estimation
Research Question
Use 5- 25 carbon chains for regression model
Use regression eqn to estimate the b/p for structural isomers
Find the % error using expt values with predicted values.
Using molecular weight 3rd order as estimator for b/p.
Using carbon chain 3rd order as estimator for b/p.
Using carbon fraction power fit as estimator for b/p.
Using CF and MW model as estimator for b/p
Molecular
formula
Number
carbon
Molecular
weight
Carbon
fraction
Boiling
point
CH4 1 16 0.2 -161.5
C2H6 2 30 0.25 -89.42
C3H8 3 44.1 0.272 -42
C4H10 4 58.12 0.285 -1
C5H12 5 72.15 0.294 36
C6H14 6 86.18 0.3 69
C7H16 7 100.21 0.304 98.4
C8H18 8 114.23 0.307 114.23
C9H20 9 128.2 0.31 128.2
C10H22 10 142.28 0.3125 142.28
Molecular
formula
Number
carbon
Molecular
weight
Carbon
fraction
Boiling
point
CH4 1 16 0.2 -161.5
CH4 = carbon fraction =
1 𝑐𝑎𝑟𝑏𝑜𝑛
1 𝑐𝑎𝑟𝑏𝑜𝑛+4 ℎ𝑦𝑑𝑟𝑜𝑔𝑒𝑛
=
1
5
= 0.2
Boiling point = 49.5(carbon fractions)0.2791 x (molecular weight)0.5039 - 273
This model is based on density function theory and polarized continuum model
done by researcher. Click here to more info

2. Isomerism
Molecules with same molecular formula but diff arrangement of atom
Two types of Isomerism
Positional Chain Isomer Functional Gp Isomer
C – C – C – C – OH
C4H10O1
Structural Isomerism
• Same molecular formula
• Diff structural formula
• Diff arrangement of atom
Diff hydrocarbon chain skeleton
• Same molecular formula
• Same structural formula
• Diff spatial arrangement of atom
Stereoisomerism
Hydrocarbon Chain Isomer
Diff functional gp position Diff functional gp
C – C – C – OH
‫׀‬
CH3
C – C – C –C
‫׀‬
OH
C – C – C – C
‫׀‬
OH
C – C – C – C
‫׀‬
OH
C – C – C – O – C
Optical Isomer
Geometric Isomer
Isomer Physical
property
Chemical
property
Structural isomer
- Hydrocarbon chain
- Functional gp position
- Functional gp
Different
Different
Different
Similar
Similar
Different
Geometrical isomer Different Similar
Optical isomer Similar Similar
Structural formula – arrangement atoms in molecule (2/3D)
H H
‫׀‬ ‫׀‬
H - C – C – H
‫׀‬ ‫׀‬
H H
CH3CH3
ethane
Display full SF Condensed SF Ball/stick model Spacefilling
Click here chemical search.
Data source for b/p
Data PubChem. Click here
Data PubChem. Click here
Data Handbook. Click here data

3. Diff functional
gp position
C4H9OH
Structural Isomerism
• Same molecular formula
• Diff structural formula
• Diff arrangement of atom
Diff hydrocarbon
chain skeleton
Diff functional
gp position
Diff functional gp
CH3-CH2-CH2-CH3
‫׀‬
OH
Butan–1-ol
CH3-CH-CH2-OH
‫׀‬
CH3
2-Methylpropan-1-ol
CH3
‫׀‬
CH3-C-OH
‫׀‬
CH3
CH3-CH2-CH-CH3
‫׀‬
OH
2-Methylpropan-2-ol Butan-2-ol
CH3-CH2-CH2-O-CH3
Methoxypropane
CH3-CH2-O-CH2-CH3
Ethoxyethane
7 structural isomers
CH3-CH-O-CH3
‫׀‬
CH3
CH3-CH2-CH2=CH2
C4H8
CH3-CH=CH-CH3
CH3-C=CH2
‫׀‬
CH3
CH2 – CH2
‫׀‬ ‫׀‬
CH2 - CH2
C4H9Br
CH3-CH2-CH2-CH2
‫׀‬
Br
CH3-CH2-CH-CH3
‫׀‬
Br
CH3
‫׀‬
CH3-C-Br
‫׀‬
CH3
CH3- CH-CH2
‫׀‬ ‫׀‬
CH3 Br
C6H14
CH3-CH2-CH2-CH2-CH2-CH3 CH3-CH-CH2-CH2-CH3
‫׀‬
CH3
CH3-CH2-CH-CH2-CH3
‫׀‬
CH3
CH3
‫׀‬
CH3-C-CH2-CH3
‫׀‬
CH3
CH3- CH- CH-CH3
‫׀‬ ‫׀‬
CH3 CH3
Diff hydrocarbon
chain skeleton
Diff functional
gp position
Diff functional
gp
Diff hydrocarbon
chain skeleton
4 structural isomers 4 structural isomers
5 structural isomers
Diff hydrocarbon
chain skeleton

4. Structural Isomerism
• Same molecular formula
• Diff structural formula
• Diff arrangement of atom
C3H6O
H
‫׀‬
CH3-CH2-C=O
O
‖
CH3-C-CH3
OH
‫׀‬
CH3-CH=C-H
OH
‫׀‬
CH2=CH-CH2
CH3-O-CH=CH2
C4H8O
CH3-CH2-CH2-C-H
‖
O
CH3 -CH2 -C-CH3
‖
O
CH3-CH - C-H
‫׀‬ ‖
CH3 O
CH2=CH-CH2-CH2-OH CH3-CH=CH-CH2-OH CH3-CH2-CH=CH-OH
CH3-CH2-O-CH=CH2
CH3-CH=CH-O-CH3
C5H10
CH2=CH-CH2-CH2-CH3
CH3-CH=CH-CH2-CH3
CH2=C-CH2-CH3
‫׀‬
CH3
CH2=CH-CH-CH3
‫׀‬
CH3
CH3-CH=C-CH3
‫׀‬
CH3
CH2-CH-CH2-CH3
CH2
CH3-CH-CH-CH3
CH2
CH3
‫׀‬
CH2– C-CH3
CH2
CH2
CH2 CH2
‫וּ‬
‫׀‬ ‫׀‬
CH2 –CH2
CH2 –CH-CH3
‫׀‬ ‫׀‬
CH2– CH2
Aldehyde Ketone Alkene/Alcohol Alkene/Alcohol Alkene/Ether
5 structural isomers
8 structural isomers
10 structural isomers
Cyclo – ring structure

5. C5H11Br
Structural Isomerism
• Same molecular formula
• Diff structural formula
• Diff arrangement of atom
CH3-CH2-CH2-CH2-CH2-Br CH3-CH2-CH2-CH-CH3
‫׀‬
Br
CH3-CH2-CH-CH2-CH3
‫׀‬
Br
CH3-CH-CH2-CH2-Br
‫׀‬
CH3
CH3-CH2-CH-CH2-Br
‫׀‬
CH3
CH3
‫׀‬
CH3–CH–CH-CH3
‫׀‬
Br
CH3
‫׀‬
CH3-CH2- C-CH3
‫׀‬
Br
CH3
‫׀‬
CH3-C-CH2-Br
‫׀‬
CH3
CH3- CH- CH-Br
‫׀‬ ‫׀‬
CH3 CH3
CH3 CH3
‫׀‬ ‫׀‬
CH3- C - CH2
‫׀‬
Br
CH3
‫׀‬
CH3-CH2- C-Br
‫׀‬
CH3
C3H6O2
CH3-CH2-C-OH
‖
O
CH3 - C- O-CH3
‖
O
H- C-O-CH2-CH3
‖
O
CH2- CH = CH
‫׀‬ ‫׀‬
OH OH
CH=C-CH3
Ι Ι
OH OH
HO-C=CH-CH3
‫׀‬
OH
HO-CH-CH=CH2
‫׀‬
OH
OH
‫׀‬
CH3-CH–C-H
‖
O
CH2- C = CH2
‫׀‬ ‫׀‬
OH OH
OH
‫׀‬
CH2-CH2-CH
‖
O
CH3-O-CH2-CH
‖
O
CH2 = C-O-CH3
‫׀‬
OH
CH2= CH-O-CH2
‫׀‬
OH
CH=CH-O-CH3
‫׀‬
OH
2-bromo-3-methylbutane 2-bromo-2-methylbutane
8 structural isomers
Alcohol / Alkene
Carboxylic acid Ester Aldehyde / Alcohol
Alcohol / Alkene / Ether
14 structural isomers

6. MW 3rd order as predictor for b/p CC 3rd order as predictor for b/p
CF power fit as predictor for b/p
Research Question
Use 5- 25 carbon chains for regression model
Use regression to estimate the b/p for structural isomers
Using MW 3rd order as estimator for b/p.
Using CC 3rd order as estimator for b/p.
Using CF power fit as estimator for b/p.
Using CF and MW model as estimator for b/p
y = 6E-06x3 - 0.0064x2 + 3.0855x - 153.76
R² = 0.9998
0
100
200
300
400
500
0 50 100 150 200 250 300 350 400
b/p
molecular weight
molecular weight vs b/p
3rd order fit
b/p = 0.000006x3 – 0.0064x2 + 3.0855x – 153.76
y = 0.0171x3 - 1.2705x2 + 43.433x - 155.23
R² = 0.9992
0
100
200
300
400
500
0 5 10 15 20 25 30
b/p
number of carbon chains
number of carbon chains vs b/p
3rd order fit
b/p = 0.0171x3 – 1.2705x2 + 43.433x – 155.23
y = 5E+13x22.772
R² = 0.9932
0
200
400
600
0.29 0.295 0.3 0.305 0.31 0.315 0.32 0.325 0.33
b/p
carbon fraction
carbon fraction vs b/p
power fit
b/p = 5 x 1013 x22.772
Boiling point = 49.5(carbon fractions)0.2791 x (molecular weight)0.5039 - 273
This model is based on density function theory and polarized continuum
model done by researcher. Click here to more info
CF and MW model as predictor for b/p

7. Predict b/p carbon 6 –CC -6
3rd order fit, y = 0.0171x3 – 1.2705x2 + 43.433x – 155.23
b/p=0.0171(6)3 – 1.2705(6)2 + 43.433(6) – 155.23 = 63
Predict b/p carbon 6 – carbon fraction CF – 0.3
power fit, y = 5 x 1013 x22.772
b/p= 5 x 1013 (0.3)22.772 = 66
Predict b/p carbon 6 – MW 86.18
3rd order fit, y = 0.000006x3 – 0.0064x2 + 3.0855x – 153.76
0.000006(86.18)3 – 0.0064(86.18)2 + 3.0855(86.18) – 153.76 = 68
Predict b/p carbon 6 – carbon fraction – 0.3, MW – 86.18
b/p = 49.5(carbon fractions)0.2791 x (molecular weight)0.5039 – 273
b/p = 49.5(0.3)0.2791 x (86.18)0.5039 – 273 = 61
Research Question
Use regression to predict b/p for structural isomers, 6 carbons
Using MW 3rd order as predictor for b/p.
Using CC 3rd order as predictor for b/p.
Using CF power fit as predictor for b/p.
Using CF and MW model as predictor for b/p
Structural Isomers
6 carbons
b/p
predict
using MW
(% error)
predict
using CC
(% error)
predict
using CF
(% error)
predict using
MW + CF
(% error)
hexane 69
2-methylpentane 60
3 -methylpentane 63
2,2 -dimethylbutane 50
2,3 -dimethylbutane 58
Min b/p 50
Max b/p 69
Mean b/p 60 68 (13%) 63 (5%) 66 (10%) 61 (1.6%)
% error =
(𝑬𝒙𝒑𝒕 𝒗𝒂𝒍𝒖𝒆 −𝑷𝒓𝒆𝒅𝒊𝒄𝒕𝒆𝒅 𝒗𝒂𝒍𝒖𝒆)
𝑬𝒙𝒑𝒕 𝒗𝒂𝒍𝒖𝒆
x 100%
% error =
(𝟔𝟎 −𝟔𝟖)
𝟔𝟎
x 100% = 13%

8. Structural Isomers
7 carbons
b/p
predict
using MW
(% error)
predict
using CC
(% error)
predict
using CF
(% error)
predict using
MW + CF
(% error)
heptane 98
2-methylhexane 90
3 -methylhexane 92
3 -ethylpentane 94
2,2 -dimethylpentane 79
2,3 -dimethylpentane 90
2,4 -dimethylpentane 80
3,3 -dimethylpentane 86
2,2,3 - trimethylbutane 81
Min b/p 80
Max b/p 98
Mean b/p 88 97 (10%) 92 (5%) 89 (1%) 89( 1%)
Predict b/p carbon 7 –CC -7
3rd order fit, y = 0.0171x3 – 1.2705x2 + 43.433x – 155.23
b/p=0.0171(7)3 – 1.2705(7)2 + 43.433(7) – 155.23 = 92
Predict b/p carbon 7 – carbon fraction CF – 0.304
power fit, y = 5 x 1013 x22.772
b/p= 5 x 1013 (0.304)22.772 = 89
Predict b/p carbon 7 – MW 100.2
3rd order fit, y = 0.000006x3 – 0.0064x2 + 3.0855x – 153.76
0.000006(100.2)3 – 0.0064(100.2)2 + 3.0855(100.2) – 153.76 = 97
Predict b/p carbon 7 – carbon fraction – 0.304, MW – 100.2
b/p = 49.5(carbon fractions)0.2791 x (molecular weight)0.5039 – 273
b/p = 49.5(0.304)0.2791 x (100.2)0.5039 – 273 = 89
Research Question
Use regression to predict b/p for structural isomers, 7 carbons
Using MW 3rd order as predictor for b/p.
Using CC 3rd order as predictor for b/p.
Using CF power fit as predictor for b/p.
Using CF and MW model as predictor for b/p
% error =
(𝑬𝒙𝒑𝒕 𝒗𝒂𝒍𝒖𝒆 −𝑷𝒓𝒆𝒅𝒊𝒄𝒕𝒆𝒅 𝒗𝒂𝒍𝒖𝒆)
𝑬𝒙𝒑𝒕 𝒗𝒂𝒍𝒖𝒆
x 100%
% error =
(𝟖𝟖 −𝟗𝟕)
𝟖𝟖
x 100% = 10%

9. Predict b/p carbon 8 – carbon fraction CF – 0.307
power fit, y = 5 x 1013 x22.772
b/p= 5 x 1013 (0.307)22.772 = 105
Predict b/p carbon 8 – MW 114.2
3rd order fit, y = 0.000006x3 – 0.0064x2 + 3.0855x – 153.76
0.000006(114.2)3 – 0.0064(114.2)2 + 3.0855(114.2) – 153.76 = 124
Predict b/p carbon 8 –CC -8
3rd order fit, y = 0.0171x3 – 1.2705x2 + 43.433x – 155.23
b/p=0.0171(8)3 – 1.2705(8)2 + 43.433(8) – 155.23 =120
Predict b/p carbon 8 – carbon fraction – 0.307, MW – 114.2
b/p = 49.5(carbon fractions)0.2791 x (molecular weight)0.5039 – 273
b/p = 49.5(0.307)0.2791 x (114.2)0.5039 – 273 = 114
Structural Isomers
8 carbons
b/p
predict using
MW
(% error)
predict using
CC
(% error)
predict using
CF
(% error)
predict using
MW + CF
(% error)
2 - methylheptane 117.8
3-methylheptane 119
4 -methylheptane 117.86
3 - ethylhexane 118.68
2,2-dimethylhexane 106.99
2,3 -dimetylhexane 115.76
2,4 -dimetylhexane 109.58
2,5 -dimetylhexane 109.26
3,3 -dimetylhexane 112.12
3,4 -dimetylhexane 117.88
2 -methyl-3-
ethylpentane
115.8
3 -methyl-3-
ethylpentane
118.41
2,2,3 -
trimethylpentane
109.99
2,2,4 -
trimethylpentane
99.39
2,3,3 -
trimethylpentane
114.92
2,3,4 -
trimethylpentane
113.62
2,2,3,3 -
tetramethylbutane
106.62
Min b/p 99.39
Max b/p 119.07
Mean b/p 113.16 124 (9.5%) 120 (6%) 105 (7%) 114 (0.7%)
Research Question
Use regression to predict b/p for structural isomers, 8 carbons
Using MW 3rd order as predictor for b/p.
Using CC 3rd order as predictor for b/p.
Using CF power fit as predictor for b/p.
Using CF and MW model as predictor for b/p
% error =
(𝑬𝒙𝒑𝒕 𝒗𝒂𝒍𝒖𝒆 −𝑷𝒓𝒆𝒅𝒊𝒄𝒕𝒆𝒅 𝒗𝒂𝒍𝒖𝒆)
𝑬𝒙𝒑𝒕 𝒗𝒂𝒍𝒖𝒆
x 100%
% error =
(𝟏𝟏𝟑.𝟏𝟔 −𝟏𝟐𝟒)
𝟏𝟏𝟑.𝟏𝟔
x 100% = 9.5%

10. Structural Isomers
7 carbons
b/p
predict
using MW
(% error)
predict
using CC
(% error)
predict
using CF
(% error)
predict using
MW + CF
(% error)
Min b/p 80
Max b/p 98
Mean b/p 88 97 (10%) 92 (5%) 89 (1%) 89( 1%)
Structural Isomers
8 carbons
b/p
predict
using MW
(% error)
predict
using CC
(% error)
predict
using CF
(% error)
predict using
MW + CF
(% error)
Min b/p 99.39
Max b/p 119.07
Mean b/p 113.16 124 (9.5%) 120 (6%) 105 (7%) 114 (0.7%)
Research Question
Use regression to predict b/p for structural isomers, 6,7,8 carbons
Using MW 3rd order as predictor for b/p.
Using CC 3rd order as predictor for b/p.
Using CF power fit as predictor for b/p.
Using CF and MW model as predictor for b/p
Structural Isomers
6 carbons
b/p
predict
using MW
(% error)
predict
using CC
(% error)
predict
using CF
(% error)
predict using
MW + CF
(% error)
Min b/p 50
Max b/p 69
Mean b/p 60 68 (13%) 63 (5%) 66 (10%) 61 (1.6%)
Structural Isomers
6,7,8 carbons
Mean
b/p
predict
using MW
(% error)
predict
using CC
(% error)
predict
using CF
(% error)
predict using
MW + CF
(% error)
6 carbon isomers 60 68 (13%) 63 (5%) 66 (10%) 61 (1.6%)
7 carbon isomers 88 97 (10%) 92 (5%) 89 (1%) 89 (1%)
8 carbon isomers 113.16 124 (9.5%) 120 (6%) 105 (7%) 114 (0.7%)
% error, smallest for MW + CF model.
% error decrease as number of structural isomer increase
% error changes from 1.6% to 1% to 0.7% as structural
isomers for carbon increase from 6 to 7 to 8.