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Alkaline hydrolysis rates coefficients for the series of methyl 3-(7-substituted-1-naphthyl) propynoate was calculated in 70%v/v dimethylsulphoxide-water at various temperatures (25,30,40, and 50̊ C). The pKa values of 3-(7-substituted-1-naphthyl) propynoic acid and (E)- 3-(7-substituted-1-naphthyl) propenoic acid calculated in 80%w/w 2-methoxyethanol-water at room temperature (25.0̊ C). logk2 of esterification rate coefficients for 3-(7-substituted-1-naphthyl) propynioc acid and (E)-3(7-substituted-1-naphthyl) propenioc acid with DDM have been measured at 30.0̊ C. Reversed substituent dipolar effects were found in the ionization reaction. In the esterification reaction with DDM the result show similar but reduced substituted effects. Rate retardations was found in the alkaline hydrolysis. It could be result from steric effect or reversal of substituent dipolar effect with a combination of steric effect.

N-heterocyclic carbenes (NHCs), and macrocyclic NHCs in particular, have been applied successfully to the stabilization of high oxidation states on transition metal complexes. This access to high oxidation states has enabled their application in oxidative catalysis including aziridination and epoxidation. However, the number of macrocyclic tetra-NHC ligands is still limited, especially those featuring anionic charge, which is beneficial in this regard. In this manuscript, we report a facile and high yielding synthesis for only the second example of such a dianionic, macrocyclic tetra-NHC ligand. This 16-atom macrocycle has the ring size and charge of a porphyrin but with the increased electron donation of NHCs. Its Fe(II) and Fe(III) complexes are reported, and their reactivities for ligand addition and oxidation were tested. Multiple oxidation catalysis reactions were tested with both the Fe(II) and Fe(III) complexes with reagents such as trimethylamine-N-oxide, oxygen (from air), diazodiphenylmethane, a...

The kinetics of the reaction of benzoic, 2-methylbenzoic, phenylacetic, cyclohex-1-enecarboxylic, 2-methylcyclohex-1-enecarboxylic, and cyclohex-1-eneacetic acids with diazodiphenylmethane was studied at 30, 33, 37, 40, and 45°C in a set of 12 protic and aprotic solvents. The reactions were found to follow the second-order kinetics. The activation energy as well as the activation parameters, such as the standard entropy, the standard enthalpy, and the standard Gibbs energy of the activation, was calculated from the second-order rate constants. The solvent and structural effects on the activation energy and the standard Gibbs energy of activation, for each examined compound, were analyzed. The results of Kamlet–Taft multiple correlation analysis show that the specific solvent–solute interactions play a dominant role in the governing of the reaction. The signs of the equation coefficients support the proposed reaction mechanism.

Protic and aprotic solvent effects on the reactivity of picolinic, nicotinic and isonicotinic acid, as well as of some substituted nicotinic acids with diazodiphenylmethane (DDM) were investigated. In order to explain the kinetic results through solvent effects, the second-order rate constants for the reaction of the examined acids with DDM were correlated using the Kamlet-Taft solvatochromic equation. The correlations of the kinetic data were carried out by means of the multiple linear regression analysis and the solvent effects on the reaction rates were analyzed in terms of the contributions of the initial and the transition state. The signs of the equation coefficients support the already known reaction mechanism. The solvatation models for all the investigated acids are suggested and related to their specific structure.

The rate constants for the reactions of diazodiphenylmethane (DDM) with 2-substituted nicotinic acids in nine aprotic solvents at 30?C were determined. The obtained second order rate constants in aprotic solvents were correlated using the Kamlet?Taft solvatochromic equation in the complete form: log k = log k0 + s?* + a??+ b?. The correlations of the kinetic data were realized by means of multiple linear regression analysis. The obtained results were analyzed in terms of the initial and the transition state of the reaction and compared with previously determined kinetic data for nicotinic acid. The signs of the equation coefficients (s, a and b) are in agreement with the reaction mechanism and the influence of the solvent on the reaction rate is discussed based on the correlation results. The mode of the transmission of the substituent effect is discussed in light of the contribution of solute?solvent interaction to the reactivity of the acid. The substituent effect was additionally analyzed by the Hammett equation, log k = p??+ log k0.

The rate constants for the reaction of 2-substituted cyclohex-1-eneacetic and 2-substituted phenylacetic acids with diazodiphenylmethane were determined in various aprotic solvents at 30°C. To explain the kinetic results through solvent effects, the second-order rate constants of the examined acids were correlated using the Kamlet–Taft solvatochromic equation. The correlations of the kinetic data were carried out by means of multiple linear regression analysis, and the solvent effects on the reaction rates were analyzed in terms of initial and transition state contributions. The opposite signs of the electrophilic and the nucleophilic parameters are in agreement with the well-known mechanism of the reaction of carboxylic acids with diazodiphenylmethane. The quantitative relationship between the molecular structure and the chemical reactivity is discussed, as well as the effect of the molecular geometry on the reactivity of the examined compounds. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 41: 613–622, 2009

Diazodiphenylmethane (DDM) undergoes cycloadditions to 1-substituted buta-1,3-dienes exclusively at the C(3)C(4) bond. At room temperature, the N2 loss from the initially formed 4,5-dihydro-3H-pyrazoles 2 is faster than the cycloaddition and furnishes the vinylcyclopropane derivatives 7 and 9 with structural retention at the C(1)C(2) bond. 2-Substituted butadienes react with DDM at the C(3)C(4) bond to give 12; isoprene, however, affords 3,4/1,2 products in the ratio of 86 : 14. DDM is a nucleophilic 1,3-dipole: 1-Cyanobutadiene reacts 400 times faster than 1-methoxybuta-1,3-diene (DMF, 40°). The log k2 for the additions to six 1-substituted butadienes show a linear correlation with σp (Hammett) and ϱ=+2.9; the log k2 of five 2-substituted butadienes are linearly related to Taft's σI (ϱ=+1.7). The structures of the vinylcyclopropanes 7, 9, and 12 are established by NMR spectra and oxidation. A cyclopropyl carbinyl cation is made responsible for the isomerization of 12, R=Ph, Me, by acetic acid to 4-substituted 1,1-diphenylpenta-1,3-dienes 25 and 29; TsOH at 200° converts 25 further to 9,10-dihydro-9-methyl-10-phenyl-9,10-ethanoanthracene (27). Thermal rearrangement of 7, 9, and 12 at 200–300° produces the 3- or 1-substituted 4,4-diphenylcyclopentenes 30 and 31. These give the same mass spectra as the vinylcyclopropanes, and an open-chain distonic radical cation is suggested as common intermediate. Besides spectroscopic evidence for the cyclopentene structures, hydrogenation and epoxidation are described; NMR data support the trans-attack by perbenzoic acid.

Rate constants for the reaction of diazodiphenylmethane (DDM) with 4-pyrimidinecarboxylic, 6-hydroxy-4-pyrimidinecarboxylic and 5-hydroxyorotic acids were determined in twelve protic solvents at 30 °C using the well known UV-spectrophotometric method. The second order rate contants for the examined acids were correlated using the appropriate solvent parameters by the equation log k = log k0 + af(e) + bs * + cngH were f(e) is the Kirkwood function of relative permittivity [(e-l)/(2e + 1 )], s * is the Taft polar constant for the alkyl group R in the alcohol ROH, and nyH is themumber of hydrogen atoms in the (-position in the alcohol. The results obtained for the investigated acids were compared with the corresponding results for benzoic, 2- and 3-hydroxybenzoic acids and the influence of the structure of the investigated acids on the reactivity in hydroxylic solvents is discussed. It was also possible to evaluate and distinguish the specific and non-specific solvent effects and their influence on the reaction rate. Konstante brzina reakcija diazodifenilmetana (DDM) sa 4-pirimidinkarboksilnom, 6-hidroksi-4-pirimidinkarboksilnom i 5-hidroksiorotinskom kiselinom su određene u dvanaest protičnih rastvarača na 30 °C korišćenjem poznate UV-spektrofotometrijske metode. Konstante brzina reakcija drugog reda su korelisane sa odgovarajućim parametrima rastvarača korišćenjem solvatohromne jednačine u sledećem obliku: k = log k0 + af(e) + bs * + cngH gde je broj f(e) Kirkwood-ova funkcija permittivity [(e-l)/(2e + 1 )] relativne permitivnosti,, s * je Taft-ova konstanta alkil-grupe R alkohola ROH, i nyH je broj (-vodonikovih atoma. Dobijeni rezultati su poređeni sa rezultatima korelacija za benzoevu, kao i 2- i 3-hidroksibenzoevu kiselinu kako bi se diskutovao uticaj strukture ispitivanih kiselina u hidroksilnim rastvaračima na njihovu reaktivnost. Takođe su procenjeni specifični i nespecifični efekti rastvarača i njihov uticaj na brzinu ispitivanih reakcija.

The rate constants for the reaction of 2-methyl-cyclohex-1-enylcarboxylic, 2-phenylcyclohex-1-enylcarboxylic, and 2-methylbenzoic and 2-phenylbenzoic acids with diazodiphenyl-methane were determined in 14 various solvents at 30 ◦ C. To explain the ki- netic results through solvent effects, the second-order rate constants of the examined acids were correlated using the Kamlet-Taft solvatochromic equation. The correlations of the ki- netic data were carried out by means of multiple linear regression analysis, and the solvent effects on the reaction rates were analyzed in terms of initial and transition state contributions. The quantitative relationship between the molecular structure and the chemical reactivity has been discussed, as well as the effect of geometry on the reactivity of the examined molecules. The geometric data of all the examined compounds corresponding to the energy minima in solvent, simulated as dielectric continuum, obtained using semiempirical MNDO-PM3 energy calculations. C

Acids are the most common industrial catalysts but have the disadvantage of requiring post-reaction neutralization and salt disposal. We show the catalytic use of self-neutralizing acids. Carbon dioxide interacts with water and amines to form carbonic acid and carbamates. A similar interaction occurs with alcohols to form alkylcarbonic acids. All three solvent systems provide in situ acid formation for catalysis which can be easily neutralized by removal of carbon dioxide. However, water has poor organic solubility and amines form salts so only alkylcarbonic acids combine good organic solubility with simple neutralization via depressurization. The use of in situ acid also completely eliminates the solid salt wastes associated with many acid processes. To elucidate how to implement these systems in place of a standard acid system we compare the reaction rates of several alkylcarbonic acids with diazodiphenylmethane (DDM). We report also the effect of CO2 pressure on reaction rate of DDM as well as measure the dielectric constant of these systems. Finally, a Hammett plot is used to identify the dominant step in alkylcarbonic acid catalysis.

The rate constants for the reaction of three isomeric pyridine mono-carbocylic acid N-oxides with diazodiphenylmethane were determined at 30 ºC in thirty two protic and aprotic solvents by the well known UV spectrophotometric method. The rate constants are generally higher than for pyridine mono-carboxylic acids in a similar range of solvents, except for picolinic acid N-oxide, and also higher in protic than in aprotic solvents. The determined rate constants were correlated with solvent parameters using the Kamlet-Taft solvatochromic equation bymeans of multiple regression analysis. The sign of the equation coefficients were in agreement with the postulated reaction mechanism. The mode of the influences of the solvent is discussed on the basis of the correlation coefficients, taking into account the specific structures of the pyridine mono-carboxylic acid N-oxides. Konstante brzina reakcije između diazodifenilmetana i izomernih piridin-N-oksidkarbonskih kiselina određene u trideset dva protična i aprotična rastvarača na 30 ºC, korišćenjem poznate UV spektrofotometrijske metode, analizirane su u funkciji efekata rastvarača. Vrednosti konstanti brzina su generalno veće za piridin-N-oksid- karbonske kiseline u odnosu na piridin-monokarbonske kiseline, izuzev pikolin-N-oksid-kiseline, a takođe vrednosti konstanti brzina su veće u protičnim rastvarač ima u poređenju sa aprotičnim za obe serije kiselina. Određene konstante brzina su korelisane sa parametrima rastvarača korišćenjem Kamlet-Taft solvatohromne jednačine izvedene metodom višestruke regresione analize. Znak koeficijenata u dobijenim korelacijama je u saglasnosti sa pretpostavljenim reakcionim mehanizmom. Uticaj rastvarača na vrednosti reakcionih konstanti je diskutovan na osnovu dobijenih korelacionih rezultata, uzimajući u obzir specifičnu strukturu piridin- N-oksid-monokarbonskih kiselina.

The rate constants for the reaction of different cycloalkenylcarboxylic, cycloalkenylacetic acids, and phenylacetic acid with diazodiphenylmethane were determined in 12 aprotic solvents at 30°C. In order to explain the kinetic results through solvent effects, the second-order rate constant of the examined acids was correlated using the Kamlet–Taft solvatochromic equation. The correlations of the kinetic data were carried out by means of multiple linear regression analysis, and the solvent effects on the reaction rates were analyzed in terms of initial and transition state contributions. The opposite signs of the electrophilic and the nucleophilic parameters are in agreement with the well-known mechanism of the reaction of carboxylic acids with diazodiphenylmethane. The quantitative relationship between the molecular structure and the chemical reactivity is also discussed. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 361–367, 2005

The rate constants for the reaction of diazodiphenylmethane with 2-(2-substituted cyclohex-1-enyl)acetic acids and 2-(2-substituted phenyl)acetic acids, previously determined in seven hydroxylic solvents, were correlated using the total solvatochromic equation, of the form logk = logk0 + s¶*+ aα + bβ, the two-parameter model, logk=logk0 + s¶*+ aα and a single parameter model logk = logk0 + bβ, where ¶*is a measure of the solvent polarity, α represents the scale of solvent hydrogen bond acceptor basicities and β represents the scale of solvent hydrogen bond donor acidities. The correlations of the kinetic data were carried out by means of multiple linear regression analysis and the solvent effects on the reaction rates were analyzed in terms of initial state and transition state contributions. Konstante brzina za reakciju između diazodifenilmetana i 2-(2-supstituisanih cikloheksen-1-enil)sirćetnih i 2-(2-supstituisanih fenil)sirćetnih kiselina prethodno određene u sedam alkoholnih rastvarača na 30 ºC, korelisane su totalnom solvatohromnom jednačinom oblika: logk = logk0 + s¶*+ aα + bβ kao i dvoparametarskom logk=logk0 + s¶*+ aα i jednoparametarskom logk = logk0 + bβ, gde je ¶*mera polarnosti rastvarača, α predstavlja skalu baznosti rastvarača kao akceptora protona u vodoničnoj vezi, β skalu kiselosti rastvarača kao donora protona u vodoničnoj vezi. Korelacija kinetičkih parametara je izvršena metodom višestruke linearne regresione analize. Suprotni znaci uz elektrofilni i nukleofilni parametar su u skladu sa navedenim reakcionim mehanizmom. Slaganje eksperimentalno određenih konstanti brzina sa izračunatim vrednostima je potvrda ispravnosti primenjenog modela. Rezultati prikazani u ovom radu omogućuju kvantitativno razdvajanje i procenu ukupnih efekata rastvarača na polazno i prelazno stanje u reakciji karbonskih kiselina sa DDM-om u alkoholnim rastvaračima.

Rate konstants for the reaction of eight 5-substituted orotic acids with diazodiphenylmethane (DDM) in dimethylformamide (DMF) were determined at 30 ºC by the known spectrophotometricmethod. The determined rate constants were correlated with the equations: logk2 = ασ1+βσR+h logk2 = ασ1+βσR+ψν+h to detect the presence and investigate the influence of both electrical and steric substituent effects. The obtained results show that the electrical effect (the localized – field and delocalized – resonance) is predominant and that the steric effect, althought present, is releatively small in this reaction. Konstante brzine za reakciju osam 5-spstituisanih orotinskih kiselina sa diazodifenilmetanom (DDM) određene su na 30 ºC u dimetilformamidu (DMF) kao rastvarač u, poznatom spektrofotometrijskim metodom. Konstante brzina ispitivanih reakcija korelisane su sledećim jednačinama: logk2 = ασ1+βσR+h logk2 = ασ1+βσR+ψν+h sa ciljem da se odrede efekti supstituenata. Dobijeni rezultati ukazuju na to da su električni efekti supstituenata (induktivni i rezonantni) preovlađujući, a da su sterni efekti supstituenata, iako su prisutni, u odnosu na njih relativno mali.

The rate constants for the reaction of diazodiphenylmethane with 2-(2-substituted cyclohex-1-enyl)acetic acids and 2-(2-substituted phenyl)acetic acids, previously determined in seven hydroxylic solvents, were correlated using the total solvatochromic equation, of the form logk = logk0 + s?*+ a? + b?, the two-parameter model, logk=logk0 + s?*+ a? and a single parameter model logk = logk0 + b?, where ?*is a measure of the solvent polarity, ? represents the scale of solvent hydrogen bond acceptor basicities and ? represents the scale of solvent hydrogen bond donor acidities. The correlations of the kinetic data were carried out by means of multiple linear regression analysis and the solvent effects on the reaction rates were analyzed in terms of initial state and transition state contributions.

The paper reports the tin(II) chloride catalyzed reactions of diazodiphenylmethane with the cis- and trans-1,2-cyclohexanediols and R,S-1,2-propanediol in 1,2-dimethoxyethane and the identification of the monodiphenylmethyl ethers formed. The catalyst is shown to work for both the cis- and trans-cyclohexanediols, but the catalyst is unstable at high reagent concentrations, especially in the case of the trans-isomer. Conditions where catalyst destruction is negligible show that the rate of the reaction with the trans-isomer is larger than with the cis-isomer. The reactions with 1,2-propanediol show small difference between the selectivity for the primary and secondary hydroxyl groups. This is in contrast with the tin(II) chloride catalyzed reactions of diazomethane and diazophenylmethane in methanol with carbohydrates, glycerol and ribonucleosides, where the primary hydroxyl group does not react.

The rate constants of 2-substituted nicotinic acids in reaction with diazodiphenylmethane (DDM) in eight alcohols at 30 ºC have been determined. In order to explain the obtained results through solvent effects, the second order reaction rate constants (k) of the examined acids were correlated using the appropriate solvent parameters by the equation: logk=logk0 af(ε) + bσ* + cnγH where f(ε) is the measure of solvent ability as a dielectric to stabilize the separation of opposite charges in the activated complex, σ* is the measure of solvent ability to stabilize proton in the initial state and nγH represents the ability of protic solvents to form hydrogen bond with the negative end of the ion-pair intermediate. These constants were correlated also by using solvatochromic equation of the form logk=logk0 + s¶* + aα + bβ where ¶* is the measure of the solvent polarity, α represents the scale of the solvent hydrogen bond donor acidities (HBD) and β represents the scale of the solvent hydrogen bond acceptor basicities (HBA). The correlations of the kinetic data were carried out by means of multiple linear regression analysis. The results obtained for 2-substituted nicotinic acids were compared with the results for ortho-substituted benzoic acid under the same experimental conditions. U ovom radu određene su konstante brzine reakcije esterifikacije 2-supstituisanih nikotinskih kiselina sa supstituentima H, Cl, OH,SCH3 iCH3 u osam alkoholnih rastvarača korišćenjem poznate UV-spektrofotometrijske metode. Dobijeni rezultati konstanti brzina reakcije 2-supstituisanih nikotinskih kiselina kaoiliteraturnih podataka za orto-supstiuisane benzoeve kiseline korelisani su korišćenjem jednačine oblika: logk=logk0 + af(ε) bσ* + cnγH gde f(ε) definiše meru stabilizacije razdvojenih naelektrisanja u prelaznom stanju dielektričnim svojstvima rastvarača, σ* definiše meru stabilizacije karboksilatnog protona rastvaračem polaznog stanja i nγH definiše meru mogućnosti građenja vodonične veze rastvarača sa negativnim krajem jonskog para. Dobijeni rezultati su takođe korelisani korišćenjem solvatohromne jednačine oblika: logk=logk0 + s¶* + aα + bβ gde ¶* predstavlja meru polarnosti rastvarača, α definiše kiselost rastvarača kao donora protona u interakciji građenja vodonične veze (HBD), i β definiše baznost rastvarača kao akceptora protona u interakciji građenja vodonične veze (HBA). Diskutovani su dobijeni rezultati za koeficijente višestruke regresione analize obe jednačine koji su dali zadovoljavajuće zavisnosti korelacija konstanti brzina sa parametrima rastvarača. Dobijeni rezultati su pokazali da su uticaji rastvarača više izraženi kod orto-supstituisanih benzoevih kiselina, nego kod 2-supstituisanih nikotinskih kiselina. Izuzetak je ortho-hidroksi-benzoeva kiselina na koju, zbog izuzetno izraženih vodoničnih veza, rastvarači manje utiču.

The molecular geometries and the frontier orbital energies of three diazo compounds [diazodiphenylmethane (2), the α-silyl-α-diazoketone 3 and the isomeric 2-siloxy-1-diazoalkene 4], 10 heterophospholes with a PC bond and two heterophospholes with a PN bond were obtained from DFT calculations at the B3LYP/6–311+G** level. The 1,3-dipolar cycloaddition reactivity of diazo compounds 2–4 toward the heterophospholes is discussed on the basis of FMO theory. It is concluded that in most cases, the dominant frontier orbital interaction is between the HOMO(diazo) and the LUMO(heterophosphole), and that the reactivity should decrease in the order­2 >4 >3. The 1,2-thiaphosphole 9 and 1,3-azaphosphole 10 have HOMOs of high energy and, therefore, the HOMO(heterophosphole)–LUMO(diazo) interaction is also important. Among the different types of heterophos-pholes considered here, the 2-acyl-1,2,3-diazaphosphole 5, 3H-1,2,3,4-triazaphosphole 8, 1,2-thiaphosphole 9 and 1,3,4-thiazaphosphole 14 are predicted to have the highest dipolarophilic reactivities. These conclusions are in qualitative agreement with available experimental results. Copyright © 2003 John Wiley & Sons, Ltd.

Novel reactions of various cis-(LC)Mn(CO)4 complexes (LC = a three-electron chelating ligand) with diazodiphenylmethane and 9-diazofluorene allowed the synthesis of a new type of oligomeric polynuc...

A kinetic study of the tin(II) chloride catalyzed reaction of diazodiphenylmethane with ethylene glycol in dimethoxyethane is reported. The preparation and characterization of ethylene glycol monodiphenylmethyl ether, the main product from this reaction, is also reported as well as the preparation of the two diphenylmethyl monoethers of methyl 4,6-O-benzylidene-alpha-D-glucopyranoside. An unexpected relationship between the concentration of ethylene glycol and the pseudo first-order rate constant, k', was observed in these reactions. For low concentrations of ethylene glycol (below 0.06 M), k' increases with increasing concentration of the diol. This trend is reversed for high concentrations of ethylene glycol (from about 0.06 to about 0.2 M). The apparent rate constant was also inversely related to the initial concentration of diazodiphenylmethane for the concentrations investigated. These results make the previously proposed involvement of a 1,3,2-dioxastannolane intermediate very unlikely [Petursson, S.; Webber, J.M. Carbohydr. Res. 1982, 103, 41-52]. The results suggest that more likely intermediates for these reactions involve tin(II) chloride complexes in a dynamic equilibrium with the diol.

Rate constants for the reaction of diazodiphenylmethane with cyclohex-1-enylcarboxylic acid and 2-methylcyclohex-1-enylcarboxylic acid were determined in nine aprotic solvents, as well as in seven protic solvents, at 30 ºC using the appropriate UV-spectroscopic method. In protic solvents the unsubsituted acid displayed higher reaction rates than the methyl-substituted one. The results in aprotic solvents showed quite the opposite, and the reaction rates were considerably lower. In order to explain the obtained results through solvent effects, reaction rate constants (k) of the examined acids were correlated using the total solvatochromic equation of the form: log k = log k0 + sπ* + aα + bβ, where π* is the measure of the solvent polarity, α represents the scale of the solvent hydrogen bond donor acidities (HBD) and β represents the scale of the solvent hydrogen bond acceptor basicities (HBA). The correlation of the kinetic data were carried out by means of multiple linear regression analysis and the opposite effects of aprotic solvents, as well as the difference in the influence of protic and aprotic solvents on the reaction of the two examined acids with DDM were discussed. The results presented in this paper for cyclohex-1-enylcarboxylic and 2-methylcyclohex-1-enylcarboxylic acids were compared with the kinetic data for benzoic acid obtained in the same chemical reaction, under the same experimental conditions. . Konstante brzine za reakciju između diazodifenilmetana (DDM) i cikloheks-1-enilkarbonske, kao i 2-methilcikloheks-1-enilkarbonske kiseline su određene u devet aprotičnih i sedam protičnih rastvarača, odgovarajućom UV-spektrofotometrijskom metodom. U protičnim rastvaračima nesupstituisana kiselina je pokazala veće reakcione brzine od supstituisane. Rezultati u aprotičnim rastvaračima su pokazali upravo suprotno i brzine su znatno manje. Da bi se dobijeni rezultati objasnili kroz efekte rastvarača, konstante brzine reakcije (k) su korelisane totalnom solvatohromnom jednačinom oblika: log k = log k0 + sπ* + aα + bβ, gde je π* mera polarnosti rastvarača, α predstavlja skalu baznosti rastvarača kao akceptora protona u vodoničnoj vezi, a β predstavlja skalu kiselosti rastvarača kao donora protona u vodoničnoj vezi. Korelacija kinetičkih podataka je izvršena metodom multiple linearne regresije i razmatrani su suprotni efekti aprotičnih rastvarača, kao i razlika u uticaju protičnih i aprotičnih rastvarača na reakciju dve ispitivane kiseline i DDM-a. Rezultati prikazani u ovom radu za cikloheks-1-enilkarbonsku i 2-methil-cikloheks-1-enilkarbonsku kiselinu su upoređeni sa kinetičkim podacima za benzoevu kiselinu, dobijenim u istoj hemijskoj reakciji pod istim eksperimentalnim uslovima. .

Rate constants have been determined for the reactions of diazodiphenylmethane with a number of 6-substituted nicotinic acids and p-substituted benzoic acids in twelve alcohols. Acomparative study was used to evaluate and compare the Hammett r values and solvent effects. Multiple correlations of the log k values for the reactions of 6-substituted nicotinic acids and p-substituted benzoic acids in 12 alcohols with groups of suitable solvent parameters are very successful. The transmission of electronic effects through the pyridine ring system in compared with that in benzene.

Rate constants have been determined for the reactions of diazodiphenylmethane (DDM) with 3- and 4-pyridineacetic acid, 3- and 4-pyridineacetic acid N-oxide and some meta- and para-substituted phenylacetic acids in twelve alcohols. The determined rate constants, together with literature data, were used for calculation of Hammett ? values in a series of alcohols. Secondary ? constants have been calculated for substituents in meta and para-position of phenylacetic acids not given in literature, and also ? constants for 3N, 3N-O, 4N and 4N-O in pyridineacetic acids, in alcohols used. The transmission of electronic effects through the phenylacetic acid system and pyridineacetic system is compared with that in benzene and pyridine. The multiple correlation of log k values for reaction of above acids in 12 alcohols with group of suitable solvent parameters was very successful.

Acid-catalyzed decomposition of diazodiphenylmethane (DDM) has been studied in DMSO containing varying amounts of water. The reaction was found to be first-order in DDM and first-order in acid. The Brønsted plot for a series of carboxylic acids is curved with the H+ point falling below the curve defined by the carboxylic acids. In near-anhydrous DMSO, kinetic hydrogen isotope effects (KIEs) are 1.7 and 1.6 for acetic acid and chloroacetic acid, respectively. The chloroacetic acid KIE increases with increasing water concentration, rising to 2.9 at 3.6 M water. As a function of [H2O], kHA for chloroacetic acid shows a sharply defined minimum occurring at 1 M water. This behavior and the water effect on KIE suggest that the carboxylic acid-catalyzed reactions in near-anhydrous DMSO do not use the ASE-2 mechanism attributed to the reaction of DDM in hydroxylic solvents. A mechanism, leading to an azoalkane, is suggested. Either directly or indirectly, this may lead to diphenylcarbene, which would account for the observed products: benzophenone, benzhydrol, and benzhydryl esters. For the H+ catalyzed decomposition of DDM in near-anhydrous DMSO, benzophenone is not found among the products, and we suggest that this reaction does not undergo a change in mechanism and continues to use the ASE-2 mechanism.Key words: decomposition mechanism, kinetics, solvent effect, reaction with carboxylic acids.

The rate coefficients for the esterification of a series of oxocarboxylic acids with diazodiphenylmethane have been determined in ethanol or 2-methoxyethanol at 30.0 °C. These and the rates of reaction with model compounds have been used to estimate the equilibrium constants for ring-chain tautomerism for the oxocarboxylic acids.

The rate constants for the reactions of diazodiphenylmethane (DDM) with 2-substituted nicotinic acids in nine aprotic solvents at 30°C were determined. The obtained second order rate constants in aprotic solvents were correlated using the Kamlet-Taft solvatochromic equation in the complete form: log k = log k0 + sπ*+ a( + bβ. The correlations of the kinetic data were realized by means of multiple linear regression analysis. The obtained results were analyzed in terms of the initial and the transition state of the reaction and compared with previously determined kinetic data for nicotinic acid. The signs of the equation coefficients (s, a and b) are in agreement with the reaction mechanism and the influence of the solvent on the reaction rate is discussed based on the correlation results. The mode of the transmission of the substituent effect is discussed in light of the contribution of solute-solvent interaction to the reactivity of the acid. The substituent effect was additionally analyzed by the Hammett equation, log k = pσ + log k0. Konstante brzine za reakciju diazodifenilmetana (DDM) sa 2-susptituisanim nikotinskim kiselinama u devet aprotičnih rastvarača su određene na 30 °S. Dobijene konstante brzine za reakciju drugog reda su korelisane Kamlet-Taftovom totalnom solvatohromnom jednačinom u obliku: log k = log k0 + sπ*+ a( + bβ. Korelacija kinetičkih podataka izvršena je višestrukom linearnom regresionom analizom. Dobijeni rezultati su analizirani u odnosu na osnovno i prelazno stanje i upoređeni sa ranije određenim vrednostima za nesupstituisanu kiselinu. Znaci ispred koeficijenata u jednačini su u skladu sa pretpostavljenim mehanizmom reakcije. Diskutovan je prenos efekata supstituenata na reakcioni centar uzimajući u obzir doprinos efekata rastvarača na reaktivnost ispitivanih jedinjenja. Efekat supstituenata je dodatno analiziran Hametovom jednačinom: log k = pσ + log k0.

The effects of protic and aprotic solvents on the reactivity of picolinic, nicotinic and isonicotinic acid, as well as of some substituted nicotinic acids, with diazodiphenylmethane (DDM) were investigated. In order to explain the kinetic results through solvent effects, the second-order rate constants for the reaction of the examined acids with DDM were correlated using the Camlet-Taft Solvatochromic Equation. The correlations of the kinetic data were realized by means of multiple linear regression analysis and the solvent effects on the reaction rates were analyzed in terms of the contributions of the initial and the transition state. The signs of the coefficients of the Equation support the already known reaction mechanism. Solvation models for all the investigated acids are suggested and related to their specific structure. U ovom radu analiziran je uticaj protičnih i aprotičnih rastvarača na reaktivnost pikolinske, nikotinske i izonikotinske kiseline, kao i nekoliko supstituisanih nikotinskih kiselina sa diazodifenilmetanom (DDM). Da bi se dobijeni kinetički podaci mogli objasniti pomoću efekata rastvarača, konstante drugog reda za reakciju ispitivanih kiselina i DDM-a su korelisane Kamlet-Taftovom totalnom solvatohromnom jednačinom. Korelacija kinetičkih podataka urađena je višestrukom linearnom regresionom analizom i efekat rastvarača je posmatran sa strane osnovnog stanja, odnosno reaktanata, i prelaznog stanja u reakciji. Aritmetički znaci ispred koeficijenata u jednačini su u skladu sa poznatim mehanizmom ispitivane reakcije. Solvatacioni modeli za sve ispitivane kiseline su predloženi i povezani sa specifičnostima njihovih struktura.

The reactivities of 2-substituted cyclohex-1-enylacetic acids with diazodiphenylmethane in eleven alcohols has been investigated. The solvent effect is interpreted in terms of the influence of the relative permittivity on the rate constants. The multiple linear correlation of log k with the Kirkwood function of relative permittivity, Taft σ* value for the alkyl group of the alcohol and the number of γ-hydrogen atoms in the alcohol nγH was highly successful (R= 0.9927). The log k values for the various acids were correlated by using the appropriate form of the extended Hammett equation involving inductive, resonance and steric parameters.The reaction of cyclohex-1-enylacetic acid with diazodiphenylmethane in eleven alcohols shows a good linear free energy relationship with the corresponding reaction of phenylacetic acid (R= 0.9793). The results obtained for 2-substituted cyclohex-1-enylacetic acids were compared with the results for ortho-substituted phenylacetic acids under the same experimental conditions.

The reactivities of 2-substituted cyclohex-1-enecarboxylic acids with diazodiphenylmethane in several alcohols were investigated. The rate data for these acids were correlated with a simple Hammett equation by means of the σp constants. The transmission of polar effects through the double bond, in terms of polar susceptibility constant ρ, has been discussed. For the reactions of a given acid in the various alcohols, the log k and ρ values were correlated through multiple regression on appropriate solvent parameters. The results obtained for 2-substituted cyclohex-1-enecarboxylic acids were compared with the results for ortho-substituted benzoic acids under the same experimental conditions.