Molar Heat Capacity of 1,2-Cyclohexanediol Isomers From (173 to 428) K

Abstract

Heat capacities of cis-1,2-cyclohexanediol and trans-1,2-cyclohexanediol enantiomers have been determined in the solid state in the temperature range T) (173 to 368) K for the cis-isomer and T) (173 to 373) K in the case of the trans-isomer and in the liquid state at temperatures up to 428 K. Measurements were carried out by differential scanning calorimetry using the enthalpic method. For the cis-isomer, the results show that, before the liquid state is reached, a highly disordered phase is formed. The trans-enantiomers show only a one-step fusion process. The values obtained for the solids are quite well predicted by Goodman's power law group contribution method, except for the lower temperatures. The Rûžička method was tested for the prediction of liquid state heat capacity values giving results (15 to 20) % lower than the experimental values.

Calculation of the Isobaric Heat Capacities of the Liquid and Solid Phase of Organic Compounds at and around 298.15 K Based on Their “True” Molecular Volume

“…Beyond these compilations a large number of recent papers presenting the heat-capacity data of several classes of compounds and of individual molecules of any kind as well as their temperature dependence have been published up to the present. Special mention shall be given to the hydrocarbons [49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65], halogenated hydrocarbons [66,67,68,69,70,71], unsubstituted and substituted alcohols and polyols including sugar derivatives [72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100,101,102,103,104,105,106,107], phenol derivatives [108,109], carboxylic acids […”

“…In Table 19 and Table 20 a number of examples demonstrates the expandability of the present Cp-prediction method to a range of temperatures. For many compounds, nearly perfect linearity of the temperature dependence of the heat capacity in the range between 250 and 350 K has been graphically demonstrated (specifically for hexatriacontane [51], alkylsubstituted adamantanes [53], neopentylbenzene [54], 4,4′-disubstituted biphenyls [59], tetracene and pentacene [62], 2-propenol and cyclohexylalcohols [76], adamantanols [77], monoterpenoids [85], a,ω-alkanediols [88], 1,2-cyclohexanediol [99], ribose and mannose [100], ketohexoses [101], glucose [102], sugar alcohols [103], 3,5-di-t-butylsalicylic acid [111], 2-pyrazinecarboxylic acid [116], vitamin B3 [118], 2,4-dinitrobenzaldehyde [145], various monoterpenes [147,148], 2-pyridinealdoxime [164], chloroanilines and chloronitrobenzenes [166], linear alkyldiamides [170], 2-thiobarbituric acids [175], monuron [179], 1,3,5-trithiane [189], ferrocene derivatives [198,199], cyclic siloxanes [202], adenosine [206], tryptophan [210], carnitine [211], 2-(chloromethylthio)benzothiazole [231], 2-amino-5-nitropyridine [233], 2-aminopyridine [234], 4-dimethylaminopyridine [236], 8-hydroxyquinoline [237], caffeine [238], 4′-bromomethyl-2-cyanobiphenyl [249], myclobutanil [250], fenoxycarb [251], methylprednisolone [254], N -methylnorephedrine [255], N , N -dimethylnorephedrine hydrochloride [256], risperidone […”

Polymorphism of trans-1,4-Cyclohexanediol: Conformational Isomorphism

“…For the cis-1,2, trans-1,3-, and cis-1,4-isomers, one of the OH groups is always in the axial position. [2][3][4] Some work exists on the solid-state characterization of the vicinal cyclohexanediols, [5][6][7][8][9][10][11] and interesting differences were found between the isomers. For the pure enantiomeric forms of trans-1,2-cyclohexanediol, a crystalline structure belonging to the hexagonal system, made up of biequatorial molecules, 6 and a metastable phase were identified.…”