from this figure that (a) the Kruskal Stress is low, and that (b) the scatter-plot is
highly linear.
The 2-dimensional MDS projection of the 6-dimensional eigenvalue descriptors
of the LDM are shown in Fig. 3.7.
Table 3.4 Eigenvalues from PCA of a series of carboxylic acids (non-traditional names are used
to highlight the functional groups attached to the C–COOH skeleton)
Compounds
F1
F2
F3
F4
F5
F6
pK a
Acetic Acid
3.3139 1.8157 0.9681 0.7624 0.5594 0.5410 4.76
Fluoroacetic acid
2.8279 1.7929 1.3095 0.8673 0.5903 0.5444 2.586
Difluoroacetic acid
2.4528 1.6669 1.3705 1.1398 0.8523 0.3994 1.34
Trifluoroacetic acid
2.2115 1.4565 1.1411 1.1403 1.1120 0.7399 0.52
Chloroacetic acid
2.8650 1.8055 1.3091 0.8645 0.5579 0.5375 2.866
Dichloroacetic acid
2.4669 1.6702 1.3612 1.1442 0.8436 0.4083 1.26
Trichloroacetic acid
2.2149 1.4654 1.1462 1.1454 1.0845 0.7442 0.512
Glycine
3.0611 2.6926 1.7311 0.9443 0.7691 0.5314 2.366
N-methylglycine
3.4219 2.4983 2.0691 1.5747 0.8849 0.7399 2.35
N,N-dimethylglycine
3.5031 3.1997 2.3859 1.5197 1.0354 0.8589 2.04
2-hydroxyacetic acid
2.7729 2.2391 1.7063 0.9008 0.7231 0.5576 3.83
2-mercaptoacetic acid
2.7687 2.2753 1.6337 0.8686 0.6791 0.5247 3.55
2-methylacetic acid
3.2949 2.6510 1.6724 0.9231 0.7578 0.5431 4.875
2,2-dimetylacetic acid
3.6229 2.8154 2.0677 1.5495 0.9162 0.7466 4.84
2,2,2-trimethylacetic acid 3.5044 3.4968 2.6103 1.6493 1.1271 0.8440 5.031
2-methoxyacetic acid
3.5054 2.5375 1.6007 1.1461 0.8160 0.6961 3.57
2-cyanoacetic
2.8160 2.2821 1.6958 0.8868 0.7173 0.4891 2.45
2-ethylacetic acid
3.4123 2.6025 2.4643 1.5942 0.9186 0.7470 4.82
2,2-diethyl acetic acid
3.6628 2.9875 2.5368 2.4024 1.9023 1.4590 4.71
2-phenylacetic acid
2.9070 2.3874 2.2992 2.1406 1.6469 1.4845 4.31
Fig. 3.6 Shepard plot of the
transformed six dimensional
data listed in Table 3.4
78
C.F. Matta et al.
highly linear.
The 2-dimensional MDS projection of the 6-dimensional eigenvalue descriptors
of the LDM are shown in Fig. 3.7.
Table 3.4 Eigenvalues from PCA of a series of carboxylic acids (non-traditional names are used
to highlight the functional groups attached to the C–COOH skeleton)
Compounds
F1
F2
F3
F4
F5
F6
pK a
Acetic Acid
3.3139 1.8157 0.9681 0.7624 0.5594 0.5410 4.76
Fluoroacetic acid
2.8279 1.7929 1.3095 0.8673 0.5903 0.5444 2.586
Difluoroacetic acid
2.4528 1.6669 1.3705 1.1398 0.8523 0.3994 1.34
Trifluoroacetic acid
2.2115 1.4565 1.1411 1.1403 1.1120 0.7399 0.52
Chloroacetic acid
2.8650 1.8055 1.3091 0.8645 0.5579 0.5375 2.866
Dichloroacetic acid
2.4669 1.6702 1.3612 1.1442 0.8436 0.4083 1.26
Trichloroacetic acid
2.2149 1.4654 1.1462 1.1454 1.0845 0.7442 0.512
Glycine
3.0611 2.6926 1.7311 0.9443 0.7691 0.5314 2.366
N-methylglycine
3.4219 2.4983 2.0691 1.5747 0.8849 0.7399 2.35
N,N-dimethylglycine
3.5031 3.1997 2.3859 1.5197 1.0354 0.8589 2.04
2-hydroxyacetic acid
2.7729 2.2391 1.7063 0.9008 0.7231 0.5576 3.83
2-mercaptoacetic acid
2.7687 2.2753 1.6337 0.8686 0.6791 0.5247 3.55
2-methylacetic acid
3.2949 2.6510 1.6724 0.9231 0.7578 0.5431 4.875
2,2-dimetylacetic acid
3.6229 2.8154 2.0677 1.5495 0.9162 0.7466 4.84
2,2,2-trimethylacetic acid 3.5044 3.4968 2.6103 1.6493 1.1271 0.8440 5.031
2-methoxyacetic acid
3.5054 2.5375 1.6007 1.1461 0.8160 0.6961 3.57
2-cyanoacetic
2.8160 2.2821 1.6958 0.8868 0.7173 0.4891 2.45
2-ethylacetic acid
3.4123 2.6025 2.4643 1.5942 0.9186 0.7470 4.82
2,2-diethyl acetic acid
3.6628 2.9875 2.5368 2.4024 1.9023 1.4590 4.71
2-phenylacetic acid
2.9070 2.3874 2.2992 2.1406 1.6469 1.4845 4.31
Fig. 3.6 Shepard plot of the
transformed six dimensional
data listed in Table 3.4
78
C.F. Matta et al.