THERMAL INDUCED HOMOLYTIC SCISSIONS OF LIGNIN INTERUNITARY BONDS IN THE HARDWOOD LIGNIN SOLUTION. AN ESR STUDY COMBINED WITH A SPIN TRAPPING METHOD

An electron spin resonance (ESR) method combined with a spin trapping reagent was successfully applied to trap and characterize unstable free radicals which were generated by heat-treatment of the dimethylsulfoxide (DMSO) solution of a hardwood, Japanese beech (Fagus crenata) lignin. It was found, consequently, that two unstable secondary carbon radicals, ～ CH? in the solution were created and the resulting radicals were trapped as the stable nitroxide spin adducts when the DMSO solution was heat-treated in the presence of a spin trapping reagent: 2,4,6-tri-tert-butylnitrosobenzene (BNB) at ca. 91°C. This means that so-called alkyl phenyl ether bonds, ～ CH-O- phenyl, known as important lignin interunitary bonds were homolytically scissoned by the heat-treatment of the lignin solution. Further the detailed analysis of the observed ESR spectrum revealed that two positions of alkyl phenyl ether bonds, i.e., β-O-4 and/or α-O-4 bonds as the interunitary linkages in the lignin are homolytically scissioned, although the phenoxy radical, Ph-O ? as the counter radical of the secondary carbon radicals was not trapped by the BNB spin trap. This suggests that fairly large steric hindrances operate between the syringyl with two methoxy moieties at the ortho positions and/or guaiacyl moieties with a methoxy moiety at the ortho position, and the BNB molecule bearing two bulky ortho tert-butyl groups in the phenyl ring.     

Novel polyureas having isobutenyl bis(aryl ether) moieties in the polymer main chain: Synthesis,tandem Claisen rearrangement,and thermal patterning on polymer film surface using microthermal analyzer

Two kinds of new polyureas 2a and 2b were synthesized by polyaddition of 1,4‐phenylene diisocyanate with 2‐{2‐[(2‐amino‐4‐methyl‐phenoxy)methyl]allyl}oxy‐5‐methyl‐aniline (diamine 1a) and 2‐{2‐[(2‐amino‐4‐tert‐butyl‐phenoxy)methyl]allyl}oxy‐5‐tert‐butyl‐aniline (diamine 1b), respectively. The isobutenyl bis(aryl ether) moiety, capable of yielding plural phenolic hydroxyls by means of tandem Claisen rearrangement (TCR), was successfully incorporated into the resulting polymer main chain. TCR at isobutenyl bis(aryl ether) moieties readily occurred by heating in the bulk state, affording phenolic hydroxy groups ortho to urea linkages. Subsequent intramolecular cyclization between the hydroxy groups and the urea groups gave the bis(2‐benzoxazolinone) derivatives, with loss of 1,4‐phenylenediamine, resulting in degradation of the polymers. At the same time, the thermal properties were investigated by TG/DTA. The degradation of these new polymers in the bulk state was shown to proceed smoothly by heating at 230°C. Using a microthermal analyzer (μTA), a preliminary study of thermal patterning on polyurea 2b film surface was carried out, and precise spot patterns were successfully processed with diameters of less than 1 μm. Two kinds of novel polyureas, containing isobutenyl bis(aryl ether) moieties ortho to the urea linkages were successfully synthesized. These results imply that these easily decomposable polymers might be used as patterning materials. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2287–2293, 2002     

Thermosensitive copolymer synthesized by controlled living radical polymerization: Phase behavior of diblock copolymers of poly(N‐isopropyl acrylamide) families

In this study, we prepared a series of thermosensitive polymers with low polydispersity index (PDI) values by nitroxide‐mediated controlled radical polymerization (NMRP) with 2,2,6,6‐tetramethyl‐1‐piperdinyloxy nitroxide (TEMPO) as a stable nitroxide‐free radical. Poly(N‐isopropyl acrylamide) (PNIPAAm)‐block‐poly(N‐tert‐butyl acrylamide) (PNTBA) was successfully synthesized, first, through polymerization with N‐isopropyl acrylamide to obtain the reactive polymer PNIPAAm‐TEMPO and, second, through polymerization by the addition of N‐tert‐butyl acrylamide (NTBA). The added molar fraction of NTBA during the second polymerization was adjusted accordingly to obtain the final polymerization product, a thermosensitive polymer (PNIPAAm‐block‐PNTBA), which had a targeted lower critical solution temperature (LCST). The result shows that the synthesis method used in this study effectively controlled the formation of the polymer to obtain a low PDI. The thermosensitive block copolymer, PNIPAAm‐b‐PNTBA (molar ratio = 9:1), with LCSTs in the range 27.7–39.8°C, was obtained through controlled living radical polymerization with PNIPAAm–TEMPO. Specifically, the 5 wt % aqueous solution of PNIPAAm‐b‐PNTBA (molar ratio = 9:1) had an LCST of 37.4°C; this was close to body temperature, 37°C. The 5 wt % aqueous solution of PNIPAAm‐b‐PNTBA (molar ratio = 9:1) showed potential for use in biomedical applications. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43224.     

Spin trapping of propagating radicals with 2,4,6-tri-tert-butyl-1-nitrosobenzene in radical polymerization initiated with di-tert-butyl hyponitrite

To examine the polar effect on spin trapping with 2,4,6-tri-tert-butyl-1-nitrosobenzene (BNB), propagating radicals from monomers were allowed to react with BNB to provide anilino radicals and nitroxides of which the amounts were determined by ESR spectroscopy. The proportion of the anilino radical increased with an increase in the steric congestion and electron donating character of the radical. Poly(vinyl ether) radicals exclusively gave the respective anilino radicals. Poly(vinyl ester) radicals yielded large amounts (>50%) of the anilino radicals, although the nitroxides were the main products (>85%) from the poly(alkyl acrylate) radicals. The polymer radicals of methyl methacrylate and ethyl itaconate only yielded the anilino radicals. The polymer radicals from ethyl -chloroacrylate and acrylonitrile reacted preferentially with the respective monomers leading to polymer formation, and the ESR spectra of the adducts were not observed.     

Nitroxide‐mediated synthesis of styrenic‐based segmented and tapered block copolymers using poly(lactide)‐functionalized TEMPO macromediators

Poly(styrene)‐poly(lactide) (PS‐PLA), poly (tert‐butyl styrene)‐poly(lactide) (PtBuS‐PLA) diblocks, and poly(tert‐butyl styrene)‐poly(styrene)‐poly(lactide) (PtBuS‐PS‐PLA) segmented and tapered triblocks of controlled segment lengths were synthesized using nitroxide‐mediated controlled radical polymerization. Well‐defined PLA‐functionalized macromediators derived from hydroxyl terminated TEMPO (PLA_T) of various molecular weights mediated polymerizations of the styrenic monomers in bulk and in dimethylformamide (DMF) solution at 120–130°C. PS‐PLA and PtBuS‐PLA diblocks were characterized by narrow molecular weight distributions (polydispersity index (M_w/M_n) < 1.3) when using the PLA_T mediator with the lowest number average molecular weight M_n= 6.1 kg/mol while broader molecular weight distributions were exhibited (M_w/M_n = 1.47‐1.65) when using higher molecular weight mediators (M_n = 7.4 kg/mol and 11.3 kg/mol). Segmented PtBuS‐PS‐PLA triblocks were initiated cleanly from PtBuS‐PLA diblocks although polymerizations were very rapid with PS segments ～ 5–10 kg/mol added within 3–10 min of polymerization at 130°C in 50 wt % DMF solution. Tapering from the PtBuS to the PS segment in semibatch mode at a lower temperature of 120°C and in 50 wt % DMF solution was effective in incorporating a short random segment of PtBuS‐ran‐PS while maintaining a relatively narrow monomodal molecular weight distribution (M_w/M_n ≈ 1.5). © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Delignification Mechanism During High-Boiling Solvent Pulping. IV. Effect of a Reducing Sugar on the Degradation of Guaiacylglycerol-β-guaiacyl Ether

Abstract

A phenolic β-O-4 type lignin model compound, guaiacylglycerol-β-guaiacyl ether was treated with 70 wt% aqueous 1,3-butanediol solution in the presence of glucose at 160–200°C to investigate the effect of reducing sugars on the degradation of lignin during high-boiling solvent (HBS) pulping. Addition of glucose increased the formation of guaiacol, coniferyl alcohol, and its γ-ethers, and decreased the formation of radical coupling compounds dramatically. These results suggest that reducing sugars may stabilize phenoxy radicals formed by homolysis of phenolic β-ethers. The kinetic studies also revealed that the disappearance of the β-ether model compound was enhanced substantially by the presence of glucose, which suggests that in addition to homolysis of the β-ether, a reducing sugar-assisted β-ether cleavage may be involved under the conditions used.     

Inhibitor radicals in styrene polymerization

Stable radicals derived from inhibitor molecules were detected in the process of styrene polymerization. N‐(1,4‐dimethylpentyl)‐4‐nitroso‐aniline and 2,4‐dinitrophenol inhibitors were shown to produce nitroxyl radicals. Phenoxyl radicals come from 4‐benzylidene‐2,6‐di‐tert‐butyl‐cyclohexa‐2,5‐dienone. The radical structures were determined. The kinetics of radical formation was studied. These radicals can participate in the process of living radical polymerization and significantly affect the kinetics of polymerization. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1599–1603, 2004     

Functionalization of high‐density polyethylene in the molten state by glycidyl methacrylate grafting

:This study concerns the melt‐free radical grafting of glycidyl methacrylate (GMA) onto high‐density polyethylene (HDPE). We studied the effect of two initiators (tert‐butyl cumyl peroxide and di‐tert‐butyl peroxide) onto HDPE. Crosslinking of polymer was observed in the presence of 0.3 wt % tert‐butyl cumyl peroxide but not with 0.3 wt % di‐tert‐butyl peroxide. The grafting was carried out in a Brabender batch mixer at 190 °C. The grafting yield of GMA onto HDPE (determined by infrared spectrometry) is weak (<1 wt % for an initial concentration in monomer of 6 wt %). Moreover, it was noted that the degree of grafting did not vary with the concentration and the nature of peroxide used. To increase the grafting yield of GMA, we added to the HDPE/peroxide/GMA system an electron‐donating monomer, such as styrene. Adding this comonomer multiplied the rate of grafted GMA 3‐ or 4‐fold, resulting in a ratio [styrene]_i/[GMA]_i = 1 mol/mol with [GMA]_i = 6 wt %. So, the copolymerization is favored compared with the homopolymerization. This kind of copolymer presenting reactive functions is very attractive in the field of compatibilizing immiscible polymers. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 581–590, 2001     

ESR study of hydroxyl alkoxyamine (HMPAP) in DMF and tert‐butylbenzene

Hydroxyl alkoxyamine (HMPAP) in DMF and in tert‐butylbenzene with oxygen as a scavenger was studied with electron spin resonance spectroscopy. From kinetics studies performed at 120°C, it was found that the rate constant of C? O bond homolysis was smaller in DMF than in tert‐butylbenzene. The difference in the behavior could be related to the formation of an activated six‐membered intermediate formed through intramolecular H‐bonding in tert‐butylbenzene and the disruption of H‐bonding in the polar solvent DMF. This led to alteration of the equilibrium constant between the alkoxyamine and the corresponding nitroxide and C‐centered radical in DMF and decreased initiating efficiency for the controlled/living radical polymerization using HMPAP as initiator. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4116–4120, 2006     

Radical-Initiated Reaction of Methyl Linoleate with Dialkyl Phosphites

The addition of dialkyl phosphite (methyl, ethyl and n‐butyl) to methyl linoleate (MeLin) double bonds was investigated. The reaction proved to be more challenging than the analogous reaction with methyl oleate (MeOl), due to inhibition of the radical reaction by the bis‐allylic hydrogens of MeLin and the lower reactivity of MeLin double bonds. However, we demonstrated that this self‐inhibition problem can be solved by simply keeping the MeLin reagent at low concentrations, while keeping the dialkyl phosphite at high concentrations. For optimization of the reaction, four different radical initiators were investigated: dilauroyl peroxide (LP), 2,2′‐azobis(2‐methylpropionitrile) (AIBN), tert‐butyl perbenzoate (t‐BP), and tert‐butyl peroxide (TOOT). The initiators were used at temperatures that provided a half‐life of 10 h: 64, 64, 104, and 125 °C respectively for LP, AIBN, t‐BP, and TOOT. The tests showed the reaction to be faster at higher temperatures, but transesterification of the ester groups was also observed at elevated temperatures. t‐BP was chosen as an optimal initiator for carrying the reaction. The apparent order of reactivity of the dimethyl, diethyl and di‐n‐butyl phosphites (Me >Et >n‐Bu) towards MeLin was due to differences in their molar volumes. When the concentrations of dialkyl phosphite were kept the same, the order reversed (n‐Bu > Et~Me). GC–MS spectra of the resulting phosphonates are reported and the main fragments assigned.     

Controlled radical double ring‐opening polymerization of 2‐methylene‐1,4,6‐trioxaspiro[4,4]nonane

Controlled radical double ring‐opening polymerization of 2‐methylene‐1,4,6‐trioxaspiro[4,4]nonane (MTN) has been achieved with tert‐butyl perbenzoate (TBPB) as initiator in the presence of 2,2,6,6‐tetramethyl‐1‐piperidinyloxy free radical (TEMPO) at 125 °C. The molecular weight polydispersity of the polymers is obviously lower than that of polymers obtained by conventional procedures. As the [TEMPO]/[TBPB] molar ratio increased, the polydispersity decreased and a polydisperty as low as 1.2 was obtained at high TEMPO concentration. With the conversion of the monomer increasing, the molecular weight of the polymers turned higher and a linear relationship between the M_w and the monomer conversion was observed. The monomer conversion, however, did not exceed 30 %. © 2000 Society of Chemical Industry     

Graft copolymers from commercial chlorinated polypropylene via Cu(0)‐mediated atom transfer radical polymerization

Commercially available chlorinated polypropylene has been used as a macroinitiator for the Cu(0)‐mediated atom transfer radical polymerization of methyl methacrylate and tert‐butyl acrylate to obtain well‐defined graft copolymers. The relatively narrow molecular weight distribution in the graft copolymers and linear kinetic plots indicated the controlled nature of the copolymerization reactions. Both Fourier transform infrared and ¹H NMR studies confirmed that the graft reactions had taken place successfully. After graft copolymer formation, tert‐butyl groups of poly(tert‐butyl acrylate) side chains were completely converted into poly(acrylic acid) chains to afford corresponding amphiphilic graft copolymers. © 2016 Society of Chemical Industry     

Preparation and characterization of poly(silyl ester)s containing 2,2‐bis(p‐dimethylsiloxy‐phenyl)propane units in the polymer backbones

The two poly(silyl ester)s containing 2,2‐bis(p‐dimethylsiloxy‐phenyl)propane units in the polymer backbones have been prepared via polycondensation reaction of di‐tert‐butyl adipate and di‐tert‐butyl fumarate with 2,2‐bis(p‐chloro dimethylsiloxy‐phenyl)propane to give tert‐butyl chloride as the condensate. The polymerizations were performed under nitrogen at 110°C for 24 h without addition of solvents and catalysts to obtain the poly(silyl ester)s with weight average molecular weights typically ranging from 5000 to 10,000 g/mol. Characterization of the poly(silyl ester)s included ¹H NMR and ¹³C NMR spectroscopies, infrared spectroscopy, ultraviolet spectroscopy, differential scanning calorimetry, thermogravimetric analysis (TGA), gel permeation chromatography, and Ubbelohde viscometer. The glass transition temperatures (T_g) of the obtained polymers were above zero because of the introducing 2,2‐bis(p‐dimethylsiloxy‐phenyl)propane units in the polymer backbones. The TGA/DTG results showed that the obtained poly(silyl ester)s were stable up to 180°C and the residual weight percent at 800°C were 18 and 9%, respectively. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1937–1942, 2006     

Grafted stock synthesis of ABS at the ultimate high ratio of polybutadiene to poly(styrene‐co‐acrylonitrile)

This study describes the emulsion grafting of styrene and acrylonitrile onto 60–70% polybutadiene (PB), in the presence or absence of tert‐dodecanetiol as a chain transfer reagent with a radical initiator, and the properties of the obtained grafted stock. There was no significant difference in terms of effect of the initiation mode on the grafting efficiency resulting from the high grafting reactivity of PB. However, the grafted stock with 70% PB prepared in the presence of tert‐dodecanetiol and the adequate selection of an initiation system gave a homogeneous dispersion of the PB particles into poly(styrene‐co‐acrylonitrile) (SAN) matrix. The initiation system involves tert‐butyl peroxylaurate, tert‐butyl peroxyacetate, and tert‐butyl peroxyisopropylcarbonate coupled with ferrous sulfate. The efficient coverage of the SAN grafted layer around 70% PB particles was observed by TEM to eventually give excellent impact resistance, high surface gloss, and good thermal resistance. The absence of tert‐dodecanetiol resulted in a toughness reduction of ABS. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3462–3470, 2001     

Fragmentation of Fluorinated Model Compounds Exposed to Oxygen Radicals: Spin Trapping ESR Experiments and Implications for the Behaviour of Proton Exchange Membranes Used in Fuel Cells

Low‐molecular weight model compounds (MCs) for Nafion membranes used in fuel cells were exposed at 300 K to ^·OH radicals produced by UV irradiation of aqueous H₂O₂ solutions. The MCs contained fluorinated and partially fluorinated groups terminated by sulphonic or carboxylic acid groups. The fragmentation process in the MCs was studied by spin trapping electron spin resonance (ESR) methods, using 5,5‐dimethylpyrroline‐N‐oxide (DMPO), N‐tert‐butyl‐α‐phenylnitrone (PBN) and 2‐methyl‐2‐nitrosopropane (MNP) as the spin traps. The objective of these experiments was to assess the effect of the type of ionic groups (sulphonic or carboxylic) and of fluorine substitution on the spin adducts detected. DMPO experiments led to the detection of spin adducts of ^·OH and of carbon‐centred radicals (CCRs), and allowed the determination of the ^·OH attack site on the ionic and/or on the protiated or fluorinated groups. CCR adducts were also detected when using PBN as a spin trap; a key point in the interpretation of the PBN results was, however, the realisation that MNP is formed during PBN exposure to UV irradiation and oxygen or other oxidants such as H₂O₂. Experiments with MNP as the spin trap were the most informative in terms of structural details for adducts obtained from each MC. The results allowed the identification of CCRs present as adducts, based on large hyperfine splittings (hfs) from, and the number of, interacting ¹⁹F nuclei; in addition, oxygen‐centred radicals (OCRs) as MNP adducts were also identified, with much lower hfs from ¹⁹F nuclei. Taken together, the results deduced by spin trapping suggest that both sulphonic acid and acetic acid groups can be attacked by ^·OH radicals and confirm two possible degradation mechanisms in Nafion membranes: initiated at the backbone and at the side chain.     

Synthesis of 2‐monoglycerides by alcoholysis of palm oil and tuna oil using immobilized lipases

Commercial immobilized lipases were used for the synthesis of 2‐monoglycerides (2‐MG) by alcoholysis of palm and tuna oils with ethanol in organic solvents. Several parameters were studied, i.e., the type of immobilized lipases, water activity, type of solvents and temperatures. The optimum conditions for alcoholysis of tuna oil were at a water activity of 0.43 and a temperature of 60 °C in methyl‐tert‐butyl ether for ～12 h. Although immobilized lipase preparations from Pseudomonas sp. and Candida antarctica fraction B are not 1, 3‐regiospecific enzymes, they were considered to be more suitable for the production of 2‐MG by the alcoholysis of tuna oil than the 1, 3‐regiospecific lipases (Lipozyme RM IM from Rhizomucor miehei and lipase D from Rhizopus delemar). With Pseudomonas sp. lipase a yield of up to 81% 2‐MG containing 80% PUFA (poly‐unsaturated fatty acids) from tuna oil was achieved. The optimum conditions for alcoholysis of palm oil were similar as these of tuna oil alcoholysis. However, lipase D immobilized on Accurel EP100 was used as catalyst at 40 °C with shorter reaction times (<12 h). This lead to a yield of ～60% 2‐MG containing 55.0‐55.7% oleic acid and 18.7‐21.0% linoleic acid.     

Poly(silyl ester)s: A new route of synthesis via the condensation of Di‐tert‐butyl ester of dicarboxylic acid with dichlorosilane

Poly(silyl ester)s were synthesized by a new route via the condensation of di‐tert‐butyl ester of dicarboxylic acid with dichlorosilane by the elimination of tert‐butyl chloride as a driving force. Three new poly(silyl ester)s with molecular weights typically ranging from 2000 to 5000 amu were produced by the condensation of di‐tert‐butyl adipate with 1,5‐dichloro‐1,1,5,5‐tetramethyl‐3,3‐diphenyl trisiloxane and di‐tert‐butyl fumarate with 1,5‐dichloro‐1,1,5,5‐tetramethyl‐3,3‐diphenyl trisiloxane or 1,3‐dichlorotetramethyl disiloxane. Each polymer was characterized with infrared, ¹H‐NMR, and ¹³C‐NMR spectroscopy, gel permeation chromatography, differential scanning calorimetry, and thermogravimetric analysis. This new approach showed several advantages. First, it did not require a catalyst or solvent. Second, the tert‐butyl chloride byproduct was volatile and was easily eliminated. Third, there was no reaction between the growing poly(silyl ester)s and the condensation byproduct, tert‐butyl chloride. Fourth, the monomers could be readily purified. Finally, the polymerization could be performed at relatively low temperatures and in a short time. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1378–1384, 2006     

Palladium(II)‐Catalyzed Direct ortho‐C?H Acylation of Anilides by Oxidative Cross‐Coupling with Aldehydes using tert‐Butyl Hydroperoxide as Oxidant

An efficient palladium‐catalyzed C H acylation with aldehydes using tert‐butyl hydroperoxide (TBHP) transforms various anilides into synthetically useful 2‐aminobenzophenone derivatives under mild conditions (40 °C, 3 h). The acylation reaction exhibits excellent regioselectivity and functional group tolerance, and simple aromatic aldehydes, functionalized aliphatic aldehydes and heteroaromatic aldehydes are effective coupling partners. The acylation reaction is probably initiated by a rate‐limiting electrophilic C H cyclopalladation (k_H/k_D=3.6; ρ⁺=−0.74) to form an arylpalladium complex, followed by acyl radical functionalization.     

Synthesis and characterization of hyperbranched poly(silyl ester)s

Hyperbranched poly(silyl ester)s were synthesized via the A₂ + B₄ route by the polycondensation reaction. The solid poly(silyl ester) was obtained by the reaction of di‐tert‐butyl adipate and 1,3‐tetramethyl‐1,3‐bis‐β(methyl‐dicholorosilyl)ethyl disiloxane. The oligomers with tert‐butyl terminal groups were obtained via the A₂ + B₂ route by the reaction of 1,5‐dichloro‐1,1,5,5‐tetramethyl‐3,3‐diphenyl‐trisi1oxane with excess amount of di‐tert‐butyl adipate. The viscous fluid and soft solid poly(silyl ester)s were obtained by the reaction of the oligomers as big monomers with 1,3‐tetramethyl‐1,3‐bis‐β(methyl‐dicholorosilyl)ethyl disiloxane. The polymers were characterized by ¹H NMR, IR, and UV spectroscopies, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The ¹H NMR and IR analysis proved the existence of the branched structures in the polymers. The glass transition temperatures (T_g's) of the viscous fluid and soft solid polymers were below room temperature. The T_g of the solid poly(silyl ester) was not found below room temperature but a temperature for the transition in the liquid crystalline phase was found at 42°C. Thermal decomposition of the soft solid and solid poly(silyl ester)s started at about 130°C and for the others it started at about 200°C. The obtained hyperbranched polymers did not decompose completely at 700°C. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3430–3436, 2006     

Advanced oxidation with ozone of 1,3,6‐naphthalenetrisulfonic acid in aqueous solution

The kinetics of oxidation with ozone of 1,3,6‐naphthalenetrisulfonic acid was analysed by studying the influence of different experimental parameters such as the concentration of tert‐butyl alcohol (2‐methyl‐2‐propanol), initial concentration of the acid, pH, and temperature. The rate constant of the direct reaction at 25 °C was calculated (k_D = 6.72 M ^?1s^?1). The constant of the free radical reaction was determined with the competitive kinetics method, using sodium 4‐chlorobenzoate as reference compound, obtaining a value of k_OH = 3.7 × 10⁹ M ^?1s^?1. It was demonstrated that even at very acid pH values, 80% of the 1,3,6‐naphthalenetrisulfonic acid was degraded by free radical reactions, so that the ozonation of this acid may be considered an advanced oxidation process. © 2002 Society of Chemical Industry