1. Are there any ways to estimate melting points? What do melting points measure? “Melting is a function of the detailed structure of the crystalline state, and that diverse laws of melting must be looked for because of the diversity of the crystal structure” -Alfred Ubbelohde, “Melting and Crystal Structure” 1965.

2. Figure. Melting temperatures of the even n-alkanes versus the number of methylene groups, circles; experimental data

3. Figure. Melting points of the odd alkanes versus the number of methylene groups; circles: experimental data

4. Figure. The correlation between the function 1/[1-T f (n)/T f (  )] and the number of methylene groups, n, for the even n-alkanes.

5. Figure.The correlation between the function 1/[1-T f (n)/T f (  )] and the number of methylene groups for the odd n-alkanes.

6. Figure. Melting temperatures of the odd 1-alkenes, n-alkylbenzenes, n-carboxylic acids, N- (2-hydroxyethyl)alkanamides and 1,  -dicarboxylic acids versus the number of methylene groups, circles, squares triangles and hexagons: experimental data; lines: calculated results.

7. Conclusions drawn from the n-alkane results: The melting point of an alkane is not a group property. 2.The odd and even members of the series should be segregated. 3.The melting point of any long chain approaches the melting point of polyethylene. Since the nature of what is attached to the end of the polyethylene is not crucial to the properties of the polymer produced, we surmised that the mp behavior observed in n-alkanes should apply to any homologous series. 4.The first few members of the series usually deviate from the observed hyperbolic behavior.

8. T fus = T f (  )*[1- 1/(mn + b)]

9. Table. Melting-structure correlations of series related to polyethylene: parents with T f <411.3 K. a Homologous Series Parent Compound T f /K S m b r 2  /K n T Parent A.Hydrocarbons n-alkanes b butane 134.9 e 0.161 1.153 0.989 2.0 53 propane 85.2 o 0.172 0.948 0.994 3.5 24 1-alkenes c 1-pentene 107.9 e 0.170 0.856 0.999 7.2 9 1-butene 87.8 o 0.164 0.925 0.998 2.4 8 2-methylalkanes c 2-methylpentane 119.6 e 0.155 0.951 0.993 5.5 10 2-methylbutane 113.4 o 0.144 1.18 0.998 2.1 9 3-methylalkanes c 3-methylhexane 100.2 e 0.145 0.981 0.984 4.8 6 3-methylheptane 152.7 o 0.129 1.19 0.996 2.4 7 4-methylalkanes c 4-methylheptane 152.2 e 0.125 1.29 0.998 1.5 6 4-methyldecane d 195.7 o 0.128 1.23 0.995 2.1 7 5-methylalkanes e 5-methyldecane d 183.2 e 0.121 1.24 0.995 1.9 7 5-methylnonane 186.7 o 0.113 1.41 0.996 2.0 6

10. 2,3-dimethylalkanes c 2,3-dimethyldecane d 183.7 e 0.155 0.898 0.989 4.0 5 2,3-dimethylheptane 156 o 0.15 0.884 0.991 7.4 6 2,4-dimethylalkanes c 2,4-dimethylundecane d 197.7 e 0.136 1.13 0.992 2.6 5 2,4-dimethyldecane d 183.2 o 0.128 1.16 0.997 2.0 6 2,4,6-trimethylalkanes e 2,4,6-trimethyltridecane d 171.2 e 0.151 0.781 0.962 7.5 4 2,4,6-trimethyldodecane d 161.2 o 0.114 1.04 0.957 7.8 4 n-alkylcyclopentanes f propylcyclopentane 155.8 e 0.155 1.23 0.999 0.6 8 ethylcyclopentane 134.7 o 0.155 1.17 0.999 1.6 8 n-alkylcyclohexanes f propylcyclohexane 178.3 e 0.165 1.45 0.999 0.6 7 ethylcyclohexane 161.4 o 0.164 1.47 0.999 4.1 9 n-alkylbenzenes c propylbenzene 173.6 e 0.166 1.21 0.999 1.4 8 ethylbenzene 178 o 0.164 1.23 0.999 3.4 10 1-alkylnaphthalenes g 1-propylnaphthalene 263.2 e 0.190 1.67 0.997 1.4 4 1-ethylnaphthalene 259.3 o 0.171 1.77 0.998 6.7 6 2-alkylnaphthalenes g 2-propylnaphthalene 270.2 e 0.131 2.29 0.955 3.5 5 2-ethylnaphthalene 265.7 o 0.149 2.15 0.987 6.8 6 Alkynes f 1-pentyne 167.5 e 0.172 1.15 0.999 0.7 9 1-butyne 147.5 o 0.180 0.993 0.999 2.0 9

11. B. Cycloalkanes m b r 2  /K n T Cycloalkanes h 0.1881.180.8562146

12. Figure. Melting temperatures of the cycloalkanes versus the number of methylene groups. Both even and odd members are included.

13. C.Functionalized Alkanes Homologous Series Parent Compound T f /K S m b r 2  /K n T 1-alkanols i propanol147.2e0.2390.9680.9981.918 ethanol143.2o0.2440.9530.9994.015 2-alkanols j 2-nonanol d 184.7e0.2570.870.9923.1 6 2-butanol158.5o0.2441.220.9991.1 9 1-alkanethiols c 1-ethanethiol125.9o0.1531.120.9982.6 8 methyl alkanoates k methyl hexanoate202.2e0.1791.300.9952.617 methyl propanoate185.2o0.1671.260.9914.111 alkyl ethanoates c propyl ethanoate178.2e0.1611.220.9993.1 8 ethyl ethanoate189.6o0.1551.280.9997.2 9 ethyl alkanoates i ethyl butanoate172.4e0.1661.280.9991.418

14. n -alkanal c butanal176.8e 0.159 1.77 0.982 7.4 7 propanal193.2o 0.183 1.24 0.945 8.1 8 n-alkanoic acids j butanoic acid268.5e 0.270 1.72 0.998 1.2 18 propanoic acid253.5 o 0.265 1.44 0.999 1.0 15 1-chloroalkanes c 1-chloropropane150.2 e 0.160 1.07 0.997 2.4 8 chloroethane137.2 o 0.166 0.941 0.999 6.5 9 1-fluoroalkanes c 1-fluorotridecane d 276.2 e 0.183 0.839 0.999 0.3 4 1-fluoroethane130o 0.171 0.846 0.999 7.3 9 1-bromoalkanes f 1-bromopropane163.2 e 0.164 1.15 0.999 0.9 9 bromoethane154.6o 0.159 1.04 0.999 4.9 11 1-iodoalkanes f 1-iodopropane171.9 e 0.172 1.21 0.999 2.4 18 iodoethane162.1o 0.168 1.10 0.999 3.0 19 1-cyanoalkanes c 1-cyanopropane161.3 e 0.203 1.03 0.999 1.1 8 cyanoethane180.3o 0.191 1.09 0.998 2.9 9 1,2-dihydroxyalkanes c 1,2-hexanediol318.2o 0.336 2.18 0.995 5.2 7 1-N-methylamino-alkanes c methyl-n-butylamine198.2o 0.164 1.55 0.994 2.2 8

15. 1-N,N-dimethyl-aminoalkanes c dimethyl-n-ethylamine133.2o 0.165 0.774 0.999 0.3 7 2-alkanones c 2-pentanone195.2e 0.220 1.51 0.999 0.7 7 2-butanone 186.2o 0.220 1.51 0.999 1.9 8 alkyl phenyl ketones k acetophenone293.2o 0.213 2.44 0.995 0.8 5 F-[CF 2 ] 12 -[CH 2 ] n -H h F-[CF2] 12 -[CH 2 ] 2 -H344.2e 0.172 5.93 0.920 1.5 9 N-methyl alkanamides l N-methylbutanamide268e 0.461 1.37 0.999 0.8 7 N-methylpropanamide230.2o 0.435 1.13 0.999 0.6 7 2-hydroxyethyl- alkanamides l N-(2-hydroxyethyl)hexanamide 319.2e 0.435 2.93 0.967 2.1 6 N-(2-hydroxyethyl)pentanamide d 305.2o 0.639 1.71 0.993 1.4 5 p-chlorophenacyl alkanoates l p-chlorophenacyl butanoate 328.2e 0.288 3.27 0.953 6.0 6 p-chlorophenacyl propionate371.4o 0.231 4.05 0.809 8.8 7 N-octadecyl alkanamides m N-octadecyl butanamide349.7e 0.257 5.49 0.981 1.3 7

16. n-alkanamides n butanamide389.2e 0.226 9.93 0.706 3.5 12 propanamide356.2o 0.238 8.61 0.732 5.0 7 alkyl 4-nitrobenzoates o propyl 4-nitrobenzoate 308.2e 0.162 2.22 0.995 3.0 7 ethyl 4-nitrobenzoate 330.2o 0.213 1.94 0.984 6.9 9 n-alkyl 3,5-dinitrobenzoates o ethyl 3,5-dinitrobenzoate 367.2o 0.035 5.13 0.566 2.7 8 1,  dihydroxyalkanes c 1,2-dihydroxyethane260.2e 0.421 1.87 0.988 1.9 8 1,3-dihydroxypropane246.2o 0.476 0.25 0.993 8.1 6 N-(  -naphthyl)alkanamides m N-(  -naphthyl) hexanamide 380.2e 0.400 9.07 0.970 1.2 6 N-(  -naphthyl) pentanamide 385.2o 0.356 9.28 0.998 3.2 3 1,  -alkanedioic acids k 1,5-undecanedioic acid d 378o 0.730 9.30 0.925 1.9 8

17. D.Symmetrically Substituted Derivatives q sym dialkyl ether c,p diethyl ether 157.2 e0.1350.9320.9991.74 sym n-alkanoic acid anhydrides p,q butanoic anhydride 198.2 e0.3191.050.9991.4 10 propanoic anhydride 228.2 o0.2212.250.98023.85 sym di-n-alkyl sulfides r diethyl sulfide 171.2 o0.2921.010.9981.46 sym N,N-dialkylamines c diethylamine 181 e0.2981.140.91310.28 dipropylamine 210.2 o0.3201.080.9990.98 sym-tri-n-alkylamines c triethylamine 158.5 o0.2490.6550.9981.67

18. sym-1,2,3-glycerol tri-alkanoate s  form 304.8e0.2961.50 0.999 0.5 7  form 261.7 0.272 0.598 0.999 1.1 7  ' form 290.0 0.263 1.310.9990.8 7

19. Figure. Experimental melting points of the three polymorphic forms of symmetric glycerol trialkanoates ranging from decanoate to eicosanoate. Molecular packing in each series series is very similar.

20. If homologous series related to polethylene converge to the mp of polyethylene, what about other series converging to other polymers?

21. Figure.Experimental melting points as a function of the number of repeat units, circles: perfluoro-n-alkanes; squares: H[OCH 2 CH 2 ] n OH; triangles: C 2 H 5 CO-[NH(CH 2 ) 5 CO] n -NHC 3 H 7.

22. Figure. A plot of 1/(1 – mp(n)/mp  ) versus the number of CF 2 groups. The melting point of Teflon is 605 K.

23. Table.Melting-structure correlations of series related to other polymers Parent Compound T f /K S m b r 2  /K n T n-perfluoroalkanes Teflon (T f 605 K) perfluorobutane 164 e 0.159 0.768 0.999  1.3 6 perfluoropropane 125.5 o0.1400.8550.920  14.34 PolyethersPolyoxyethylene (T f 342 K) H[OCH 2 CH 2 ] 2 OH 267.2 e0.4073.360.884  4.78 H[OCH 2 CH 2 ]OH 260.6 o0.5542.340.953  5.28 PolyamidesNylon-6 (T f 533 K) H[NH(CH 2 ) 5 CO] 2 OH 471.2 e0.08910.00.650  0.85 HNH(CH 2 ) 5 COOH 479.2 o 0.046 9.90.599  1.6 10

24. What if the melting temperature of the parent is greater than 411 K?

25. Figure 6.Experimental melting or smetic/nematic  isotropic transition temperatures for the odd series of 4-alkoxy-3-fluorobenzoic acids, trans-4’-n-alkoxy-3-chlorocinnamic acids, 6-alkoxy-2-naphthoic acids, and the even series of 8-alkyltheophyllines; symbols: experimental data; lines: calculated results.

26. Figure. Melting temperatures of the dialkylarsinic acids (odd series)

27. Figure. A plot of [1/(1- T  /T(n)] vs n for the dialkylarsinic acids. A value of 380 K was used for T .

28. Ascending hyperbola T fus = T f (  )*[1- 1/(mn + b)] Descending hyperbola T fus = T f (  )/[1- 1/(mn + b)]

29. Some of the compounds that show descending behavior relative to the parent show liquid crystalline behavior. For these compounds, which temperature correlates with the melting temperature of members of the series that do not form liquid crystals?

30. nematic Liquid Crystals

31. Figure. Circles: melting temperatures or temperatures at which the trans-4-n-alkoxy-3- chlorocinnamic acids becomes isotropic; squares are melting temperatures for compounds forming liquid crystals; triangles: smectic to nematic transitions

32. Figure. A plot of 1/[1-T(  )/T(n)] versus the number of methylene groups for trans-4-n-alkoxy-3- chlorocinnamic acids. The solid circles represent melting temperatures, the solid squares represent nematic to isotropic transitions, the circles represent smectic to nematic transitions and the squares represent from nematic to isotropic transitions. The temperatures at which the liquids become isotropic appear to correlate best. A value of 380 K was used for T(  ).

33. Why do the first few members of the series usually deviate from the observed hyperbolic behavior?

34. Why do homologous series exhibit melting points that behave in a hyperbolic fashion?

35. Figure. Total phase change enthalpies of the n-alkanes.

36. Figure. Total phase change entropies of the n-alkanes

37. Figure. Total phase change enthalpies of the dialkyl arsenic acids as a function of the size of the alkyl group.

38. Figure. Total phase change entropies of the dialkyl arsenic acids as a function of the size of the alkyl group.

39. Fusion Enthalpies N- Alkanes  tpce H(T f )/J. mol -1 = (3725  38)n - (1838  7500); (37 data points) r 2 = 0.9964 Di-n-alkylarsinic acids  tpce H(T f )/J. mol -1 = 2 (3348  66) n + (9512  2800); (17 data points) r 2 = 0.9941

40. Total Phase Change Entropies (Fusion Entropies)  tpce S(T f ) = (A s )n + (B s ) J. mol -1. K -1 N-Alkanes  tpce S(T f ) = (9.3)n + (35.2) J. mol -1. K -1 ; Di-n-alkylarsinic Acids  tpce S(T f ) = 2(9.3)n + (11.2) J. mol -1. K -1 ;

41.  G =  H - T f  S ; at T f, :  G = 0 T f =  tpce H/  tpce S = (A H n + B H )/(A S n + B S ); N-Alkanes T f =  tpce H(T f ) = (3725)n - (1838)  tpce S(T f ) (9.3)n + (35.2) Di-n-alkylarsinic Acids T f =  tpce H(T f ) = 2 (3348)n+ (9512)  tpce S(T f ) 2(9.3)n + (11.2)

42. Figure. The melting point behavior of the even n-alkanes and the dialkylarsinic acids of formula [CH 3 (CH 2 ) n ] 2 AsOH when calculated as a ratio of the total phase change enthalpy to the total phase change entropy. Both were estimated by group additivity.

43. Figure. The distribution of errors based on the use of three experimental data points to estimate the melting behavior of each series for 995 compounds.