Volumetric properties of methyl,tert-butyl, and alkoxy derivatives of tetraphenylporphyrin in benzene solution

Densities, apparent molar volumes, and partial molar volumes of benzene solutions ofmeso-tetradimethylphenyl porphyrin derivatives H₂T(i,j-CH₃)PP (where i,j = 2,3-; 2,4-; 3,4-; 2,5-; 3,5-);meso-tetra-4-alkoxyphenyl porphyrin derivatives H₂T(4-OC_nH_2n+1)PP (wheren = 2–4,6–8,10,12,16);meso-tetra-3-butoxyphenyl porphyrin H₂T(3-OC₄H₉)PP;meso-tetra-4-tert-butylphenyl porphyrin H₂T(4tBu)PP;meso-tetra-3,5-ditert-butylphenyl porphyrin H₂T(3,5-tBu)PP at 25°C and tetraphenylporphyrin, H₂TPP,H₂T(4-OC₁₀H₂₁)PP;H₂T(4-OC₁₂H₂₅)PP and H₂T(4tBu)PP at 20°C; 30°C; 40°C; 50°C were determined. The solubilities of the compounds in benzene at 25°C were measured. The solvent excluded volumes for different conformational states and the topology of dimethyl derivatives of tetraphenylporphyrin were calculated and compared with partial molar volume data. The correlation between the partial molar volumes and van der Waals volumes for the derivatives H₂TPP,n-alkanes,n-alkanols, fatty acids, cyclic compounds, and crown ethers using the equation of Terasawa was elaborated. The average increment of the methylene group for alkoxy-substituted H₂TPP was calculated as δV ₂ ^o (CH₂) = 16.6±0.4cm³-mol^-1. The volumetric expansion coefficients of benzene solutions of H₂TPP; H₂T(4-OC₁₀,H₂₁)PP; H₂T(4-OC₁₂H₂₅)PP and H₂T(4-tBu)PP were determined and discussed. The importance of packing efficiencies around the solute molecules were examined.