Calorimetric and volumetric studies of dilute aqueous solutions of cyclic ether derivatives

185

CARMEL JOLICOEUR and GHYSLAIN LACROIX. Can. J. Chem. 54, 624 (1976). The density and specific heat of dilute aqueous solutions of various alcollols and polyols have been measured at 25 "C. Such measurements have been carried out for the following solutes : methanol, ethanol, 11-propanol, 11-butanol, isobutanol, s-butanol, rert-butyl alcohol, 11-pentanol. 3-pentanol, r~eo-pentanol, ethyleneglycol, 1,4-butanediol, 1,6-hexanediol, dimethyl-2,2-propanediol, l,l,l-tris(hydroxymethyl)ethane, and pentaerythritol.The limiting apparent molal volume +, O and heat capacities 4, O derived from these data exhibit some variations among the properties of isomers (e.g. branched vs. normal alkyl groups). but these variations cannot be conclusively attributed to specific effects in the hydration of the alkyl groups. On the other hand, the data allows one to derive group contributions to +, O and +,O, namely A+O(CH?) for the methylene group, A+O(OH) for the O H functional group and 14O(H) for the C-H of a terminal methyl group.The concentration dependence of +, and +, brings out some interesting new features. With most of the alcohols, +, decreases with concentration, in a way related to the degree of hydrophobicity of the alcohol. Solute-solute interactions contribute to reduce +, of the hydrophilic solutes, but the opposite effect is observed with the most hydrophobic alcohols.

Section: Discussionsupporting

confidence: 81%

Section: Discussionmentioning

confidence: 99%

Thermodynamic properties of aqueous organic solutes in relation to their structure. Part III. Apparent molal volumes and heat capacities of low molecular weight alcohols and polyols at 25 °C

Jolicoeur¹,

Lacroix²

1976

185

“…In fact, we find that for molecules containing three or more alkyl carbon atoms for each hydrophilic group (hydroxyl, ether, amine, amide, or urea) [2] with A = 0.53 A works reasonably well. This is illustrated for eight apolar molecules in (14), tetrahydropyran (12,18,24), dioxane (18,24), npropylamine (16), n-butylamine (16), t-butylamine (12), n-pentylamine (16), n-hexylamine (16), n-heptylamine (16), diethylamine (16), di-n-propylamine (16), diethylmethylamine (16), piperidine (1 6), heptamethyleneimine (1 6), N-methylpyrrolidine (16), N-methylpiperidine (16), isopropyl urea (21), n-butylurea (21), 1,l-diethylurea (21), 1,3-diethylurea (21), and tetramethylurea (21,23).…”

Section: Shrinkage Of the Solvent Cavity When It Containsmentioning

confidence: 99%

Relation between van der Waals and Partial Molal Volumes of Organic Molecules in Water

Edward¹,

Farrell²

1975

. Can. J. Chem. 53,2965Chem. 53, (1975. The partial molal volumes ii of nonpolar organic molecules (i.e. those having more than three aliphatic carbon atoms per polar hydroxyl, ether, amine, amide, or urea group) in water at 25 "Care given by their van der Waals volumes v, plus the additional empty volume provided by an enclosing shell 0.53 A thick. An equation relates fi to v,. More polar compounds (i.e. those having fewer than two or three aliphatic carbon atoms per polar group) have ii smaller than calculated by the equation; the shrinkage in fi from that computed is linearly related to th'e fraction of the total surface area of the molecule occupied by the polar group. JOHN T. EDWARD et PATRICK G. FARRELL. Can. J. Chem. 53,2965Chem. 53, (1975. Les volumes molaires partiels ii de compos6s organiques non-polaires (i.e. ceux contenant plus que trois atomes de carbone aliphatique pour chaque groupement hydroxyle, ether, amine, amide ou urk) dans l'eau a 25 "C sont Cgaux a leurs volumes van der Waals v, avec l'increment du volume vide donne par une enveloppe d'une epaisseur de 0.53 A. La relation entre fi et v, est contenue dans une equation. Les composes plus polaires (ayant moins d'atomes de carbone aliphatique) ont ii plus petit; la diminution fractionnelle en fiest li& ala proportion de la surface molkulaire occupke par le groupement polaire.

“…Some attempts to relate the properties of aqueous solutes with their intrinsic structural features can be found, namely for acids (14), alcohols and sugars (15)(16)(17)(18), and various other solutes (19)(20)(21). These investigations were concerned primarily with different arrangements of hydrophilic groups on solute molecules rather than with the structural features of their hydrophobic groups.…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic Properties of Aqueous Organic Solutes in Relation to Their Structure. Part I. Free Energy of Transfer from H₂O to D₂O for a Series of Isomeric Ketones

Jolicoeur¹,

Lacroix²

1973

The solubilities of 18 decanones have been measured in H 2 0 and D 2 0 at 25°C from their U.V. absorption spectra. The data were used to calculate AG,O, the standard free energy of transfer of these solutes from H 2 0 to D,O. AG,O was found negative for the saturated ketones, but positive for most of the unsaturated and polycyclic isomers. A rough correlation was observed between AG,O and the degree of branching in the hydrocarbon chains of the ketones: AG,O increases with the degree of branching. From the temperature dependence of AG,D obtained at 10, 25, and 40 "C, heats of transfer AH? were determined for typical ketones, namely 2-decanone and adamantanone. AH? was found as -2.1 kcal mol-' for 2-decanone and -0 + 0.5 kcal mol-' for adamantanone.The results are discussed in terms of two main contributions: (I) an isotope effect in the free energy of cavity formation and (2) L'interpretation des resultats est donnee selon deux contributions principales aux fonctions de transfert: (1) difference dans I'tnergitique de la formation d'une cavite dans les deux solvants et (2) difference dans les effets que les solutes exercent sur la structure des solvants. La premiere contribution est evaluee a I'aide de la theorie "scaled-particle", et la specificit6 observee dans le AGP des differents solutes est attribuee i la partie structurale de la fonction de transfert.