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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.

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 three isomeric pyridine mono-carbo- cylic 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 by means of multiple re- gression analysis. The sign of the equation coefficients were in agreement with the postulated reaction mechanism. The mode of the influences of the solvent is discus- sed on the basis of the correlation coefficients, taking into account the specific struc- tures of the pyridine mono-carboxylic acid N-oxides.

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.

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 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-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.

Heating of a mixture of N,N′-(thiocarbonyl)diimidazole (= 1,1′-(carbonothioyl)bis[1H-imidazole]; 1) and 2,5-dihydro-1,3,4-thiadiazole 2a or 2b gave the 1,3-dithiolanes 4a and 4b, respectively, via a regiospecific 1,3-dipolar cycloaddition of the corresponding ‘thiocarbonyl methanides’ 3a,b onto the CS group of 1 (Schemes 1 and 2). The adamantane derivative 4b was not stable in the presence of 1H-imidazole and during chromatographic workup. The isolated 1,3-dithiole 5 is the product of a base-catalyzed elimination of 1H-imidazole from the initial cycloadduct 4b. The formation of the S,N-acetal 6 can be rationalized by a protonation of the ‘thiocarbonyl ylide’ 3b followed by a nucleophilic addition of 1H-imidazole. With the diazo compounds 8a–e (Scheme 3) 1 underwent a regiospecific 1,3-dipolar cycloaddition to give the corresponding 2,5-dihydro-1,3,4-thiadiazole derivatives 9, which spontaneously eliminated 1H-imidazole to yield (1H-imidazol-1-yl)-1,3,4-thiadiazoles 10. The structures of 10a and 10d were established by X-ray crystallography. In the case of diazodiphenylmethane (8f), the initial cycloadduct 9f decomposed via a ‘twofold extrusion’ of N2 and S to give 1,1′-(2,2-diphenylethenylidene)bis[1H-imidazole] (11; Scheme 3).

In connection with a study of the transmission of polar effects through ring double bonds, double bonds in open chain systems and delocalized double bonds, the reactivity of 2-(4-phenylsubstituted)-α,β-unsaturated carboxylic acids with diazodiphenylmethane in ethanol was investigated. The rate data for 2-(4-phenylsubstituted)-cyclohex-1-ene carboxylic acids, 2-(4-phenylsubstituted)-benzene carboxylic acids, cis-3-and 4-substituted and trans-3- and 4-substituted cinnamic acids were correlated with a simple Hammett equation by means of the σp and σm constants and with an extended Hammett equation to detect the presence or absence of steric effects as well as the composition of the electrical effect. The transmission of polar effects through the different double bonds was discussed in terms of the polar susceptibility constant δ and steric interaction of the phenyl and carboxylic group.

Rate constants for the reaction of six possible diazine monocarboxylates with diazodiphenylmethane (DDM) in ethanol, and also for the hydrolysis of the corresponding methyl carboxylate esters, have been determined at four selected temperatures. Correlations with sums of the Hammett σ constants for ring nitrogens treated as substituents, which are fairly satisfactory for the reaction with DDM at 30 °C (ρDDM= 0.64, log k0=–1.54, r= 0.92, s= 0.12) and for ester hydrolysis (ρEH= 2.28, log k0=–3.36, r= 0.94, s= 0.36) are, however, excellent for the intercorrelation of the two reaction series (ρDDM/ρEH= 0.34, r= 0.99, s= 0.12). The reactivity of ortho- and para-diazine dicarboxylates in the reaction with DDM, in ethanol and dimethylformamide, has been investigated and compared with the corresponding reactions of ortho- and para-benzene- and pyridine-dicarboxylates.

The rate coefficients for the alkaline hydrolysis of a series of 2′- and 4′-substituted 2-methoxy-carbonyldiphenylacetylenes and (Z)-2-methoxycarbonylstilbenes have been determined in 70%(v/v) dimethyl sulphoxide–water at both 30.0 and 50.0 °C and at 24.0, 30.0, 40.0, and 50.0 °C, respectively. The pKa values of (Z)-2′- and -4′-substituted 2-carboxystilbenes have been measured in 80%(w/w) 2-methoxyethanol-water at 25 °C. The rate coefficients for the esterification of the corresponding acids with diazodiphenylmethane have been measured at 30.0 °C. For the diphenyl-acetylene system, normal substituent effects are observed from both the 2′- and 4′-position. A trans-mission coefficient for polar effects of ca. 0.2 has been calculated for both positions. The evidence, including the carbonyl stretching frequencies of the esters, indicates an s-trans conformer for the 2′-substituted 2-methoxycarbonyldiphenylacetylenes. For the (Z)-stilbene system, normal substituent effects are observed from both the 2′- and 4′-position. Transmission coefficients for polar effects, with regard to both the 2′- or 4′-position and the reaction studied, vary between 0.2 and 0.7. This appears to arise from the conformers available to the (Z)-2′- and -4′-substituted 2-carboxystilbenes.

The pKa values of a series of 2′- and 4′-substituted-biphenyl-2-carboxylic acids have been determined in 80%(w/w) 2-methoxyethanol-water at 25 °C. The rate coefficients for the esterification of these acids with diazodiphenylmethane have been measured in 2-methoxyethanol at 30 °C. The transmission of polar effects from the 4′-position is normal and the transmission coefficient is ca. 0.4. However, for the normally electron-withdrawing substituents at the 2′-position, reversed dipolar substituent effects are observed in both reactions. The reactivity studies indicate that the conformation of the 2,2′-disubstituted-biphenyl system appears to be close to that having orthogonal aryl groups.

The pKa values of a series of 2′- and 4′-substituted-biphenyl-2-carboxylic acids have been determined in 80%(w/w) 2-methoxyethanol-water at 25 °C. The rate coefficients for the esterification of these acids with diazodiphenylmethane have been measured in 2-methoxyethanol at 30 °C. The transmission of polar effects from the 4′-position is normal and the transmission coefficient is ca. 0.4. However, for the normally electron-withdrawing substituents at the 2′-position, reversed dipolar substituent effects are observed in both reactions. The reactivity studies indicate that the conformation of the 2,2′-disubstituted-biphenyl system appears to be close to that having orthogonal aryl groups.

The reactivities of a series of 18 (E)-α-4-substituted phenyl-β-(3N and 4N)pyridineacrylic acids, with a wide range of substituent effects, were investigated in their reaction with diazodiphenylmethane, in dimethylformamide at 30°C, by the known spectrophotometric method. The Hammett equation in its original form has been applied to the results, using the sum of substituent constants from the both aromatic nuclei, but the overall correlation was only fair. Better insight into the transmission of substituent effects was obtained using Taft's Dual Substituent Parameter (DSP) method, where it was possible to distinguish the contributions from the inductive and resonance effects of the substituents

The pKa-values of a series of 8-(2-substituted phenyl)-1-naphthoic and 2- and 4-(8-substituted 1-naphthyl)benzoic acids have been determined in 80%(w/w) 2-methoxyethanol-water at 25 °C. The rate coefficients for the esterification of these acids with diazodiphenylmethane have been measured in 2-methoxyethanol at 30 °C. For the reactivity of the 2- and 4-(8-bromo-1 -naphthyl)benzoic acids, reversed dipolar substituent effects were observed in both reactions. The reactivities are quantitatively accounted for by either comparison with the results for the 2- and 4-bromobenzoic acids or Kirkwood–Westheimer calculations. For the reactivity of the 8-(2-substituted phenyl)-1-naphthoic acids, both normal and reversed dipolar substituent effects were observed in the ionisation reaction; whereas, for the esterfication reaction, only normal effects were shown.

The pKa values of 3-(1-naphthyl)propiolic acid, together with the 8-bromo- and 8-chloro-substituted derivative, and of (E)-3-(1-naphthyl)acrylic acid, together with the 8-bromo- and 8-chloro-substituted derivatives, have been determined in 80%(w/w) 2-methoxyethanol–water at 25 °C. The rate coefficients for the esterification of these acids with diazodiphenylmethane have been measured in 2-methoxyethanol at 30 °C. The rate coefficients for the alkaline hydrolysis of the corresponding methyl propiolates have been determined in 70%(v/v) dioxane–water at both 30.0 and 50.1 °C. In the ionisation and esterification reactions, reversed dipolar substituent effects were observed. The ΔpKa values are quantitatively accounted for either by comparison with the results for simple model compounds or by Kirkwood–Westheimer calculations. The retardations observed for the effect of 8-halo substituents in the alkaline hydrolysis reaction are in agreement with a reversed dipolar effect and no steric ‘bulk’ effects are observed.

The rate constants for the esterification of some 3-, 4-, and 5-substituted thiophene-2-carboxylic acids with diazodiphenylmethane in methanol at 25° have been measured. The reactivity of some para- and ortho-substituted benzoic acids has also been determined. Logarithmic kinetic constants for ortho-, meta-, and para-like substituted thiophene-2-carboxylic acids furnish an excellent linear free energy relationship when plotted versus Δpka (β 0.89, r 0.989, C.L. > 99.9%, n 18, i 0.04), thus confirming the peculiar behaviour of five-membered ring derivatives. The correlation with σH values offers an additional proof of the hyper-ortho character of the 2,3-relation in thiophene derivatives. para- and ortho-Substituted benzoic acids show the usual behaviour of six-membered ring derivatives.

Diazodiphenylmethane and a number of its substituted analogues have been decomposed thermally in esters of α-fluorophenylacetic acid as solvent, and the 1H and 19F CIDNP effects recorded. The pattern of the principal polarisation in the case of the methyl ester is consistent with benzylic C–H insertion by triplet diphenylmethylene. A minor 19F polarisation showing no corresponding depolarised product is attributed to a metastable product formed by bonding of PhĊFCO2Me at the para-position of the diarylmethyl radical.CIDNP has been observed during benzylic insertion into diastereoisomeric esters formed by esterification of racemic and resolved α-fluorophenylacetic acid with chiral alcohols (1 methylheptanol, bornan-2-endo-ol, p-menthan-3-ol). In the case of single diastereoisomers, the polarised 19F signals of the insertion product indicate that geminate radical pair recombination occurs with complete loss of stereochemistry at the reaction centre. However, depolarised n.m.r. spectra indicate a 55 :45 preference for retention of configuration. The species responsible for insertion with retention but without the generation of polarisation is considered to be singlet diphenylmethylene.

Rate constants for the reactions of diazodiphenylmethane (DDM) with a series of substituted 2-carboxypyridine N-oxides (3-, 4-, 5-, and 6-CO2Me, 4-NO2, 4-Cl, 4-Br, 6-Me, H, 4-OMe, 4-NH2) have been determined in absolute ethanol over the range 20–50 °C. The existence of a strong intramolecular hydrogen bond has previously been established for this particular arrangement of the N-oxide and carboxy group, and it was previously believed that this type of interaction did not conform to the Hammett relationship. It was shown, however, that log(rate constants) for the reactions of 4-substituted derivatives are well correlated with ordinary σ values of substituents with ρ 1.340, and with a sliding scale of σ values with ρ 0.677. A satisfactory correlation was obtained between log(rate constants) for the reaction of a number of the above acids with DDM and the pKa values of the conjugate acids of correspondingly substituted pyridine N-oxides. On the basis of the results, it was concluded that an equilibrium between the hydrogen-bonded and the free acid precedes proton transfer in the rate-determining step in the reaction with DDM.

The ultraviolet absorption spectra of a number of cis and trans-3- and 4-substituted cinnamic acids have been determined. Examination of the obtained spectra shows that there is a fair linear relation between the positions of the absorption bands for the electronic transitions of the carbonyl group and the Hammett substituent constants. The plot of the λ max values of the cinnamic acids versus the rate constants for he corresponding acids with diazodiphenylmethane in ethanol gave a fair correlations. This relationship was discussed in view of the proportionality of the energy of activation for the reaction of these acids with DDM in ethanol and the energy for the electronic transitions in the carbonyl group under the influence of UV radiation.

The reactivity of a series of substituted pyridine- and N-oxylpyridine-carboxylic acids with diazodiphenylmethane has been investigated and the empirical Hammett treatment applied to a study of substituent effects. In general, satisfactory additivity of substituent effects was obtained, and it was possible to correlate with the same regression line the rate constants for both investigated series. The calculated reaction constant (ρ 0·818) differs from that for substituted benzoic acids, reflecting the same attenuating effect observed in the hydrolysis of substituted pyridine carboxylates. A satisfactory correlation for the ρDDM–ρhydr relationship was obtained with literature data for the hydrolysis of corresponding substituted methyl pyridinecarboxylates.

The rate coefficients for the reaction with diazodiphenylmethane in methanol, ethanol, isopropyl alcohol, t-butyl alcohol, 2-methoxyethanol, 2-n-butoxyethanol, and ethyl acetate at 30° and the pKa values in 80% 2-n-butoxyethanol–water of a series of 9-substituted 10-anthroic and 8-substituted 1-naphthoic acids have been determined. The effect of substitution has been analyzed by linear free energy relations. The variation in the susceptibilities of the systems to polar substituent effects with the medium are examined. The occurrence of reversed dipolar substituent effects in the reactions of the 1,8-naphthoic acids is detected. The implications of the results for the inductive and field effect models for the transmission of polar effects are discussed.

The rate coefficients for the reaction with diazodiphenylmethane in ethanol at 30° and the acid-catalyzed esterification with methanol at 60° of a number of arylaliphatic carboxylic acids and their pKa values in 80% 2-methoxyethanol–water have been measured. Rate coefficients have also been measured for the alkaline hydrolysis in 70% dioxan–water of their 2-diethylaminoethyl esters at 45°. The pKa values and diazodiphenylmethane esterification rate coefficients were also measured for a series of 2-substituted fluorene-9-carboxylic acids. The latter results have been correlated by Hammett equations and the transmission of polar effects in fluorene is discussed. Polar and steric substituent constants are evaluated for the arylaliphatic systems. These values are used to successfully correlate the hydrolysis and ionization reactions using the Taft–Ingold equation.

The rate coefficients for the reaction with diazodiphenylmethane in ethanol, t-butyl alcohol, and ethyl acetate at 30° and the pKa values in water at 25° of fourteen 3-substituted acrylic acids have been determined. The effect of substitution is assessed by use of linear free energy relations. A definite incremental acid-strengthening effect solely due to cis-substitution is confirmed. This is not a "bulk" steric effect and is due solely to the orientation of substitution. The polar effect of a substituent is found to be approximately the same from the cis- or trans-position. An attempt is made to test the suggested mechanisms for the transmission of the polar effect. In the reactions studied the transmission of the polar effect in 3-substituted acrylic acid and ortho-substituted benzoic acids is approximately twice that of the meta- or para-substituted benzoic acids. This appears to be reasonably accommodated by a significant field effect.

The empirical Hammett treatment has been applied to the investigation of structure–reactivity relationships for pyridine and pyridine N-oxide carboxylic acids in the reaction with diazodiphenylmethane. The values obtained for the pyridine aza-group (σ2 0·878, σ3 0·740, σ41·105) are in good agreement with the literature values for the alkaline hydrolysis of the corresponding esters. For the N-oxide group, the σ values for the 3- and 4-positions (σ3 1·312, σ41·140) indicate that the overall effect is electron withdrawing. The negative value for the 2-position (σ2–0·395) can be explained on the basis of intramolecular hydrogen bonding. It is also shown that the Hammett relationship holds for pyridinecarboxylic acids with a fixed ortho-substituent as well.

Rate constants for the reactions of 15 substituted carboxypyridines and four substituted 2-carboxy-pyridine N-oxides with diazodiphenylmethane (DDM) in dimethylformamide (DMF) were determined at 30 °C, by the known spectrophotometric method. For comparison, rate constants for the reaction of 12 substituted benzoic acids were determined under the same conditions. Kinetic and thermodynamic parameters obtained, together with products analyses, essentially verify the previously proposed reaction mechanism in this solvent. The empirical Hammett treatment has been applied to the results, and it was shown that a scattered overall plot (ρ= 1.019, logko=–2.98, r= 0.91, s= 0.22, n= 31) was obtained with additive σ constants from the corresponding σ values for the pyridine aza-group and N-oxide group and Hammett σ constants for substituents. Fairly good separate correlations were obtained from the data for substituted benzoic acids (ρ= 1.213, logko=–2.91, r= 0.985, s= 0.12, n= 12), halogen- and nitro-substituted acids (ρ= 1.07, logko=–2.99, r= 0.998, s= 0.02, n= 5) and for the carboxypyridine N-oxides (ρ= 1.18, logko=–3.35, r= 0.995, s= 0.04, n= 4). A far less satisfactory correlation was obtained when it was applied to the substituted carboxypyridines, including the N-oxides (ρ= 1.15, logko=–3.23, r= 0.91, s= 0.18, n= 19). It was concluded that powerful solvent nucleophilic stabilisation of the reactant carboxylic acid in the initial state is greatly influenced by the type of substitution, substituent solvation, and probably also by the kind of electronic interaction of the particular substituent with the heteroaromatic nuclei.

The main results now discussed are rate coefficients for the reactions of benzoic acid and 32 ortho-substituted benzoic acids with diazodiphenylmethane (DDM) at 30.0 °C in 11 alcohols including 2-methoxyethanol. The reaction involves a rate-determining proton transfer. The results have been subjected to correlation analysis in two ways. (a) For the reactions of a given acid in the various alcohols, the log k values are correlated through multiple regression on appropriate solvent parameters. (b) For reactions in a given alcohol, the log k values for the various acids are correlated by using the appropriate form of the extended Hammett equation involving inductive, resonance, and steric parameters. Analyses of type (a), as in earlier work, involve the σ* value of the group R in the alcohol ROH, the Kirkwood function of dielectric constant, f(Iµ)=(Iµ– 1)/(2Iµ+ 1) and nγH, the number of hydrogen atoms in the γ-position in the alcohol. These correlations yield information on the influence of ortho-substituents on the relative importance of specific and non-specific solvent effects. In analyses of type (b) the correlation equations are established with a limited set of substituents (up to 18), whose characteristic parameters σI, σR, and v(determined by Charton) are well established, and are unlikely to show effects due to hydrogen-bonding or substituent conformation. The results for other substituents are then interpreted by comparing log k(calc). from a correlation expression with log k(obs.).

Rate coefficients at 30.0 °C are presented for the reaction of diazodiphenylmethane and benzoic acid in five branched-chain alkanols and in nine electronegatively substituted alcohols. As in earlier work, correlation analysis of log k values involves multiple regression on the σ* value of the group R1 in the alcohol R1OH, the Kirkwood function of dielectric constant f(Iµ)=(Iµ– 1)/(2Iµ+ 1), and nγH, the number of hydrogen atoms in the γ-position of the alcohol. The results for branched-chain alcohols provide further examples of the acceleratory effect of γ-hydrogen atoms. A correlation equation based on 27 alkanols and phenyl-substituted alcohols, for which σ* lies between –0.325 and +0.215, can be applied with reasonable success to seven electronegatively substituted alcohols, for which σ* lies in the range 0.07–0.92. 2-Methoxy- and 2-phenoxy-ethanol show marked deviations. Correlation equations properly incorporating the data for the electronegatively substituted alcohols are finally presented.

The kinetics and products of the decomposition of diazodiphenylmethane by copper(II) perchlorate and by tris-(p-bromophenyl)ammoniumyl perchlorate in acetonitrile solvent have been investigated. The similarity of the two reactions suggests that both the copper and the ammoniumyl salt act as initiators of a chain decomposition in which the chain carriers are radical cations. E.s.r. studies of reaction mixtures in other solvents, notably n-heptyl cyanide, indicate that two different radical cations are formed during the reaction; one, detectable at low temperatures, is believed to be the radical cation formed by simple removal of one electron from the diazoalkane by the initiator, and the other is shown to be the radical cation of benzophenone azine, one of the products of the reaction. In acetonitrile as solvent the major reaction product is tetraphenylethylene, but the ratio of this olefin to benzophenone azine changes from solvent to solvent and in some cases depends upon whether or not oxygen is present. The addition of water to acetonitrile leads to changes in the rate of decomposition of the diazo-compound with both initiators which indicate progressive, and at water concentrations greater than about 0.3M almost total, incursion of a perchloric acid-catalysed decomposition pathway involving rate-limiting formation of diphenylmethyl cations. This has been confirmed by measurement of the kinetic deuterium isotope effect of replacing the added water by deuterium oxide.

The nitrones PhCHN+(R)O–(R = Me, Et, PhCH2, and Ph) react rapidly with perfluoropropadiene to give the corresponding 2-R-4-difluoromethylene-5,5-difluoro-3-phenylisoxazolidines in good yield, although these isoxazolidines are unstable and decompose during catalytic hydrogenation. Perfluoropropadiene also reacts with diazophenylmethane and diazodiphenylmethane, giving 4-difluoromethylene-3,3-difluoro-5-phenyl- and 5,5-diphenyl-Δ1-pyrazolines. The diphenylpyrazoline decomposes on distillation giving 3-difluoromethylene-2,2-difluorodiphenylcyclopropane. The regiospecificity of these dipolar cycloadditions is discussed in relation to frontier orbital theory. Benzoyldiazophenylmethane decomposes during a slow reaction with perfluoropropadiene and the only adduct isolated is 3-difluoromethylene-2,2-difluoro-4,5-diphenyldihydrofuran. Diazodiphenylmethane reacts with perfluoropropyne to give a 1 : 1 adduct believed to be 5-fluoro-3,3-diphenyl-4-trifluoromethyl-3H-pyrazole.

The pKa values of a series of 5-substituted triptycene-7-carboxylic acids have been measured in 80%(w/w) 2-methoxyethanol-water at 25 °C. The rate coefficients for their esterification with diazodiphenylmethane in 2-methoxyethanol have been measured at 30 °C. The rate coefficients for the alkaline hydrolysis of the corresponding methyl esters have also been determined in 70%(v/v) dioxane–water at both 30.4 and 56.3 °C. In the ionisation reaction reversed substituent polar effects were found and Kirkwood–Westheimer calculations were carried out which confirm that they arise from a field effect. The results for the esterification reaction show similar, but reduced, substituent effects. In the alkaline hydrolysis of the esters a microscopic solvent effect was noted in addition to the dipolar substituent effects.

Rate coefficients have been determined for the reactions at 30° of diazodiphenylmethane with benzoic acid and with m-XC6H4·CO2H (X = Me, Cl, or NO2) in methanol, ethanol, propan-1-ol, propan-2-ol, 2-methylpropan-1-ol, 2-methylpropan-2-ol, 2-methylbutan-2-ol, 2-methoxyethanol, dioxan, ethyl acetate, acetone, dimethylformamide, or dimethyl sulphoxide. The reactions of benzoic acid and of m-chlorobenzoic acid in benzyl alcohol have also been studied. Log k0 and Hammett ρ values have been evaluated for the reactions in the fourteen solvents. For benzoic acid, rate coefficients have also been determined for this reaction in butan-1-ol, butan-2-ol, 2-n-butoxyethanol, diethyl oxalate, or chloroform. The reactions of p-chlorobenzoic acid with diazodiphenylmethane have also been studied in selected solvents. For many of the solvents, log k for the reaction of diazodiphenylmethane with benzoic acid may be correlated fairly well with dielectric constant by the expression log k= 0·98 – 2·60/(0·916 + 0·084Iµ) but the effect of specific interactions is usually discernible. These are believed to involve solvation of the carboxylic proton and of the transition state of the reaction. Specific interactions are most marked in dipolar aprotic solvents such as acetone, dimethylformamide, and dimethyl sulphoxide, but it is also relevant to consider them for alcohols. Limited multiple correlations of log k with pairs of solvent parameters are discussed.The Hammett ρ constant is correlated broadly with dielectric constant by the expression ρ= 0·60 + 2·40/(0·75 + 0·25Iµ), but again specific interactions are important.The rate coefficients for p-chlorobenzoic acid reacting with diazodiphenylmethane indicate a solvent dependence of the Hammett σ value for p-CI.Values for the ratio R, of the amount of diazodiphenylmethane consumed in esterification to the total consumed (esterification + etherification) are presented and discussed for the reactions with benzoic acid in a number of alcohols.

Rate coefficients have been determined for the reactions at 30° of diazodiphenylmethane with various ortho-substituted phenylacetic acids (substituents: Me, Et, Pri, But, F, Cl, Br, I, and NO2) in methanol, ethanol, propan-2-ol, 2-methylpropan-1-ol, 2-methylpropan-2-ol, and 2-methylbutan-2-ol.All four ortho-alkylphenylacetic acids are less reactive than the parent acid. The rate coefficients are interpreted in terms of the electron-releasing character of the groups, and of a primary steric effect which is most marked for the But group, and for all group in the less polar solvents.The ortho-halogenophenylacetic acids react more quickly than the parent acid in all six alcohols, in the order H o-NO2.The results for the o-alkyl groups form the basis of a separation of polar and steric effects for o-Hal and o-NO2. The essence of the treatment lies in considering the differential action of the solvent on the positive and the negative pole of the substituents in the various positions of the ring. The treatment is reasonably successful in accounting for the substituent effects in alcohols of a wide range of polarity.The multiple correlation of log ko with polar and steric parameters is briefly discussed but is regarded as inferior to the more detailed analysis already mentioned.