XXII List of Abbreviations standard chemical potential of solute i kJ.mol-! n,nD refractive index(at sodium D line) (co/c) empirical paramet r of solven nucleophilicity(Winstein and Grun ald) nucleophilicity parameter for (nucleophile+solvent)-systems (Ritchie) frequency Hzs- Hz,s-1 公 wavenumber (=1/4) cm-1 rameter. d on a Diels-Alde (Berson) P pressure Pa(←1N:m-2 bar (=10 Pa) re of solven (Palm and Koppel) polarizability P empirical solvent polarity parameter based on 19F NMR measurements (Taft) PA proton affinity kJ.mol-1 empirical solvent polarity parameter, based on theπ* -πemission of pyrene(Winnik) () ter partition coefficient pH -I9HO+1-lg c(H-O+) or puissance d'hydr 1909) -lg K internal pressure of a solvent MPa(=106 Pa) empirical solvent dipolarity/ polarizability parameter,based on theπ一π*absorption of substituted aromatics(Taft and Kamlet)
m i standard chemical potential of solute i kJ mol1 my i standard chemical potential of solute i at infinite dilution kJ mol1 n; nD refractive index (at sodium D line) (¼ c0=c) N empirical parameter of solvent nucleophilicity (Winstein and Grunwald) Nþ nucleophilicity parameter for (nucleophile þ solvent)-systems (Ritchie) n frequency Hz, s1 n frequency in the gas phase or in an inert reference solvent Hz, s1 n~ wavenumber (¼ 1=l) cm1 W empirical solvent polarity parameter, based on a Diels-Alder reaction (Berson) p pressure Pa (¼ 1N m2), bar (¼ 105 Pa) P measure of solvent polarizability (Palm and Koppel) P empirical solvent polarity parameter, based on 19F NMR measurements (Taft) PA proton a‰nity kJ mol1 Py empirical solvent polarity parameter, based on the p ! p emission of pyrene (Winnik) Po=w 1-octanol/water partition coe‰cient (Hansch and Leo) pH lg[H3Oþ], lg c(H3Oþ) (abbreviation of potentia hydrogenii or puissance d’hydroge`ne (So¨rensen 1909) pK lg K p internal pressure of a solvent MPa (¼ 106 Pa) p empirical solvent dipolarity/ polarizability parameter, based on the p ! p absorption of substituted aromatics (Taft and Kamlet) XXII List of Abbreviations
List of Abbreviations XXIII empirical solvent dipolarity/ polarizability parameter,based on the r一π*absorption of azo merocyanine dyes (Buncel) hydrophobicity parameter of substituent X in HsCo-X (Hansch) radius of sphere representing an ion cm(=10-2m) or a cavity distance between centres of two ions cm(=10-2m) or molecules density (mass divided by volume) gcm-3 P.PA Hammett reaction resp.absorption constants generalized for solvent Ig k2 for the Menschutkin reaction of tri-n-propylamine with iodomethane (Drougard and Decroocq) standard molar entropy change J.K-1 .mol-! 45 standard molar entropy of activation J.K-1.mol-1 solvophobic power of a solvent (Abraham) SA empirical parameter of solvent hydrogen-bond donor acidity (Catalan) SB oerof n-bond acceptor basicity SPP empirical parameter of solvent dipolarity/polarizability,based on the π-π'absorption of substituted7- nitrofluorenes(Catalan) Hammett substituent constant NMR screening constant Celsius temperature thermodynamic temperature melting point C boiling point U internal energy AU molar energy of vapourization kJ.mol-1
p azo empirical solvent dipolarity/ polarizability parameter, based on the p ! p absorption of azo merocyanine dyes (Buncel) px hydrophobicity parameter of substituent X in H5C6-X (Hansch) r radius of sphere representing an ion or a cavity cm (¼ 102 m) r distance between centres of two ions or molecules cm (¼ 102 m) r density (mass divided by volume) g cm3 r; rA Hammett reaction resp. absorption constants S generalized for solvent S empirical solvent polarity parameter, based on the Z-values (Brownstein) S lg k2 for the Menschutkin reaction of tri-n-propylamine with iodomethane (Drougard and Decroocq) DS standard molar entropy change J K1 mol1 DS0 standard molar entropy of activation J K1 mol1 Sp solvophobic power of a solvent (Abraham) SA empirical parameter of solvent hydrogen-bond donor acidity (Catala´n) SB empirical parameter of solvent hydrogen-bond acceptor basicity (Catala´n) SPP empirical parameter of solvent dipolarity/polarizability, based on the p ! p absorption of substituted 7- nitrofluorenes (Catala´n) s Hammett substituent constant s NMR screening constant t Celsius temperature C T thermodynamic temperature K tmp melting point C tbp boiling point C U internal energy kJ DUv molar energy of vapourization kJ mol1 List of Abbreviations XXIII
XXIV List of Abbreviations Vm:Vmi molar volume (of i) cm3.mol-1 AV* molar volume of activation cm3.mol-1 ,x(@) mole fraction of i(x=ni/>n) X empirical solvent polarity parameter based on an S2 reaction (Gielen and Nasielski) XgXB empirical solvent polarity parameters, kcalmol- based on the n一 absorption of merocyanine dyes(Brooker) oys.wys solvent-transfer activity coefficient of a solute X from a reference solvent (O)or water (W)to another solvent (S) Grunwald) empirical parameter of solvent ionizing power,based on 2-adamantyl tosylate solvolysis(Schleyer and Bentley) 2 charge number of an ion i positive for cations. negative for anions arC2nmeter kcal.mol-! absorpt substituted Pyridinium iodide(Kosower)
Vm; Vm; i molar volume (of i) cm3 mol1 DV0 molar volume of activation cm3 mol1 xi; xðiÞ mole fraction of i ðxi ¼ ni= PnÞ X empirical solvent polarity parameter, based on an SE2 reaction (Gielen and Nasielski) wR; wB empirical solvent polarity parameters, based on the p ! p absorption of merocyanine dyes (Brooker) kcal mol1 OyS X; WyS X solvent-transfer activity coe‰cient of a solute X from a reference solvent (O) or water (W) to another solvent (S) Y empirical parameter of solvent ionizing power, based on t-butyl chloride solvolysis (Winstein and Grunwald) YOTs empirical parameter of solvent ionizing power, based on 2-adamantyl tosylate solvolysis (Schleyer and Bentley) Y measure of solvent polarization (Palm and Koppel) zi charge number of an ion i positive for cations, negative for anions Z empirical solvent polarity parameter, based on the intermolecular CT absorption of a substituted pyridinium iodide (Kosower) kcal mol1 XXIV List of Abbreviations
"Agite,Auditores ornatissimi,transeamus alacres ad alind negoti um enim sic satis excusserimus ea quatuor Instrumenta artis,et naturae,quae modo relinquimus cideamus quintum genus horum,quod ipsi Chemiae fere proprium censetur,cui certe Chemistae principem locum prae omnibus assignant,in quo se jactant,serioque tri- pncis se,praeombueetu mirificos adscribuAtqueld quidem Menstruum tocaverunt. Hermannus Boerhaave(1668-1738) De menstruis dictis in chemia,in: Elementa Chemiae (1733 [1,21. 1 Introduction The develo nt of our knowledge of solutions reflects to self(31 of all l the extent the develo olvent as far hack a the tir re the solutio and dis solution. The Greek alch mists d all ch nde th In this contex he word was or diss lvent the called“Alkahest'”or“"Men vers as it called by 493-1541 dicates the give A the 15th to 18 centune id f any umerous exper ns,and n nds perforn rom th u tha like dis How words sol and dissolution comprised all operat ng to a iquid produc and it was still a long way to the conceptual distinction between the physical dissolution of a salt or of sugar in water,and the chemical change of a substrate by dissolution. example,of a metal in an acid.Thus,in the so-called chemiatry period (iatrochemistry period).it was believed that the nature of a substance was fundamentally lost upon dis solution Van Helmont (1577-1644)was the first to strongly oppose this contention.He claimed that the dissolved substance had not disappeared but was present in the solu- tion,although in aqueous form,and could be recovered [4].Nevertheless,the dissolution my dear lis let us proceed with fire.water,air,and earth)we must cons r a fifth element which can almost be considered th of which they tium ent(menstruu in a phial t er with the adhe e alkahest the he to as ridiculed by his contemporaries who asked in which vessel he has stored this universal solvent
‘‘Agite, Auditores ornatissimi, transeamus alacres ad aliud negotii! quum enim sic satis excusserimus ea quatuor Instrumenta artis, et naturae, quae modo relinquimus, videamus quintum genus horum, quod ipsi Chemiae fere proprium censetur, cui certe Chemistae principem locum prae omnibus assignant, in quo se jactant, serioque triumphant, cui artis suae, prae aliis omnibus e¤ectus mirificos adscribunt. Atque illud quidem Menstruum vocaverunt.’’*) Hermannus Boerhaave (1668–1738) De menstruis dictis in chemia, in: Elementa Chemiae (1733) [1, 2]. 1 Introduction The development of our knowledge of solutions reflects to some extent the development of chemistry itself [3]. Of all known substances, water was the first to be considered as a solvent. As far back as the time of the Greek philosophers there was speculation about the nature of solution and dissolution. The Greek alchemists considered all chemically active liquids under the name ‘‘Divine water’’. In this context the word ‘‘water’’ was used to designate everything liquid or dissolved. The alchemist’s search for a universal solvent, the so-called ‘‘Alkahest’’ or ‘‘Menstruum universale’’, as it was called by Paracelsus (1493–1541), indicates the importance given to solvents and the process of dissolution. Although the eager search of the chemists of the 15th to 18th centuries did not in fact lead to the discovery of any ‘‘Alkahest’’, the numerous experiments performed led to the uncovering of new solvents, new reactions, and new compounds**). From these experiences arose the earliest chemical rule that ‘‘like dissolves like’’ (similia similibus solvuntur). However, at that time, the words solution and dissolution comprised all operations leading to a liquid product and it was still a long way to the conceptual distinction between the physical dissolution of a salt or of sugar in water, and the chemical change of a substrate by dissolution, for example, of a metal in an acid. Thus, in the so-called chemiatry period (iatrochemistry period), it was believed that the nature of a substance was fundamentally lost upon dissolution. Van Helmont (1577–1644) was the first to strongly oppose this contention. He claimed that the dissolved substance had not disappeared, but was present in the solution, although in aqueous form, and could be recovered [4]. Nevertheless, the dissolution * ‘‘Well then, my dear listeners, let us proceed with fervor to another problem! Having su‰ciently analyzed in this manner the four resources of science and nature, which we are about to leave (i.e. fire, water, air, and earth) we must consider a fifth element which can almost be considered the most essential part of chemistry itself, which chemists boastfully, no doubt with reason, prefer above all others, and because of which they triumphantly celebrate, and to which they attribute above all others the marvellous e¤ects of their science. And this they call the solvent (menstruum).’’ ** Even if the once famous scholar J. B. Van Helmont (1577–1644) claimed to have prepared this ‘‘Alkahest’’ in a phial, together with the adherents of the alkahest theory he was ridiculed by his contemporaries who asked in which vessel he has stored this universal solvent. Solvents and Solvent Effects in Organic Chemistry, Third Edition. Christian Reichardt Copyright 8 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim ISBN: 3-527-30618-8
2 1 Introduction of a substance in a solvent remained a rather mvsterious process The famous Russian polymath Lomonosov (1711-1765)wrote in 1747:"Talking about the process of disso lution,it is generally said that all solvents penetrate into the pores of the body to be dissolved and gradually remove its particles.However,concerning the question of what forces cause this process of removal.there does not exist any somehow reasonable explanation unles one arbitrarily attributes to the solvents sharp wedges,hooks or. who knows,any other kind of tools"[271. The further development of modern solution theory is connected with three per earcher Raoult(1830-1901)[281.the Dutch physical chemist van't HofT(1852-1911)[51.and the Swedish scientist Arrhenius (1859-1927)[61.Rac effects of dissolved nonionic substances on the freezing dthen thth outeolye i the Th ion that the propo on ie nal to the mole raction of solve in the salutio is today kn as Raoult's lay 28 The dificulty in of in sical erties solutions led in to nius omplete the ph prop ete ele which empo Arrhen s de 、theo the resu oy me asurements troc ductivity an ns appl g gases lacing pres ure by extensively by 01 measur t phy mical met d i he egra three basi developments established Ithe four ations of pnzes in chemistry were awarde (in 1901)an us(in 1903)for their work electro- lytic dis tion,respectively The further development of solution chem try is connected with the pioneer work of Ostwald (1853-1932),Nernst (1864-1941),Lewis (1875- 1946.Debye(188 1966),E.Huckel (1896-1980),and Bjerrum (1879-1958).More detailed reviews on the development of modern solution chemistry can be found in references 29.30 The influence of solvents on the rates of chemical reactions [7,8]was first noted by Berthelot and Pean de Saint-Gilles in 1862 in connection with their studies on the esterification of acetic acid with ethanol:"...I'etherification est entravee et ralentie par I'emploi des dissolvants neutres etrangers a la reaction"[9)*.After thorough studies on the reaction of trialkvlamines with haloalkanes.Menschutkin in 1890 concluded that a reaction cannot be separated from the medium in which it is performed [10.In a letter to Prof.Louis Henry he wrote in 1890:"Or,I'experience montre que ces dissolvants exercent sur la vitesse de combinaison une influence considerable.Si nous representons par 1 la constante de vitesse de la reaction precitee dans I'hexane CH4,cette constante oour la meme combinaison dans CH3-CO-C6Hs,toutes choses egales d'ailleurs sera 847.7.La difference est enorme,mais,dans ce cas,elle n'atteint pas encore le maxi- to the the tion is disturbed and decelerated on addition of neutral solvents not belonging
of a substance in a solvent remained a rather mysterious process. The famous Russian polymath Lomonosov (1711–1765) wrote in 1747: ‘‘Talking about the process of dissolution, it is generally said that all solvents penetrate into the pores of the body to be dissolved and gradually remove its particles. However, concerning the question of what forces cause this process of removal, there does not exist any somehow reasonable explanation, unless one arbitrarily attributes to the solvents sharp wedges, hooks or, who knows, any other kind of tools’’ [27]. The further development of modern solution theory is connected with three persons, namely the French researcher Raoult (1830–1901) [28], the Dutch physical chemist van’t Ho¤ (1852–1911) [5], and the Swedish scientist Arrhenius (1859–1927) [6]. Raoult systematically studied the e¤ects of dissolved nonionic substances on the freezing and boiling point of liquids and noticed in 1886 that changing the solute/solvent ratio produces precise proportional changes in the physical properties of solutions. The observation that the vapour pressure of solvent above a solution is proportional to the mole fraction of solvent in the solution is today known as Raoult’s law [28]. The di‰culty in explaining the e¤ects of inorganic solutes on the physical properties of solutions led in 1884 to Arrhenius’ theory of incomplete and complete dissociation of ionic solutes (electrolytes, ionophores) into cations and anions in solution, which was only very reluctantly accepted by his contemporaries. Arrhenius derived his dissociation theory from comparison of the results obtained by measurements of electroconductivity and osmotic pressure of dilute electrolyte solutions [6]. The application of laws holding for gases to solutions by replacing pressure by osmotic pressure was extensively studied by van’t Ho¤, who made osmotic pressure measurements another important physicochemical method in studies of solutions [5]. The integration of these three basic developments established the foundations of modern solution theory and the first Nobel prizes in chemistry were awarded to van’t Ho¤ (in 1901) and Arrhenius (in 1903) for their work on osmotic pressure and electrolytic dissociation, respectively. The further development of solution chemistry is connected with the pioneering work of Ostwald (1853–1932), Nernst (1864–1941), Lewis (1875–1946), Debye (1884– 1966), E. Hu¨ckel (1896–1980), and Bjerrum (1879–1958). More detailed reviews on the development of modern solution chemistry can be found in references [29, 30]. The influence of solvents on the rates of chemical reactions [7, 8] was first noted by Berthelot and Pe´an de Saint-Gilles in 1862 in connection with their studies on the esterification of acetic acid with ethanol: ‘‘. . . l’e´the´rification est entrave´e et ralentie par l’emploi des dissolvants neutres e´trangers a` la re´action’’ [9]*). After thorough studies on the reaction of trialkylamines with haloalkanes, Menschutkin in 1890 concluded that a reaction cannot be separated from the medium in which it is performed [10]. In a letter to Prof. Louis Henry he wrote in 1890: ‘‘Or, l’expe´rience montre que ces dissolvants exercent sur la vitesse de combinaison une influence conside´rable. Si nous repre´sentons par 1 la constante de vitesse de la re´action pre´cite´e dans l’hexane C6H14, cette constante pour la meˆme combinaison dans CH3 aaCOaaC6H5, toutes choses e´gales d’ailleurs sera 847.7. La di¤e´rence est e´norme, mais, dans ce cas, elle n’atteint pas encore le maxi- * ‘‘. . . the esterification is disturbed and decelerated on addition of neutral solvents not belonging to the reaction’’ [9]. 2 1 Introduction