Kinetic studies in the chemistry of rubber and related materials. IV. The inhibitory effect of hydroquinone on the thermal oxidation of ethyl linoleate

Bolland, J. L.; Have, P. ten

doi:10.1039/tf9474300201

Cited by 122 publications

(60 citation statements)

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“…I ) , which suggests that reaction 1-61 is very slow with a hindered phenoxy radical (11,19). The deuterium isotope effect in reaction [6] \vas measured by the technique we have previously employed in which the rates of inhibited oxidations in the presence of light and heavy water are compared (I). With BNIP in tetralin the isotope effect \\,as 9.7 a t 65 "C, i.e., (k6)R/(kG)D = 9.7.…”

Section: Results a N D Discussiosmentioning

confidence: 99%

“…The fact that this \\;as not observed was attributed to the hydroperoxide forined during the determination of the initial rate, but it can also be explained by chain transfer to the substrate (see below). (6) and to the i?ahibitioc~ of the oxidation of 9,lO-dihydroanthracene by 2,6-di-l-butyl-4-~izethylpJ~enol and 2,4,6-tri-t-butylpAelie1~01 (7) and by iV-phenyl-a-and iV-phenyl-P-naplatlaylarnine (8 Secondly, Mahoney and Ferris (12) showed that the rate of the phenol inhibited oxidation of tetralin and of 9,lO-dihydroanthracene was 1.5 order with respect to hydrocarbon. This was explained by including the chain transfer reaction,…”

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confidence: 99%

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The Kinetics of the Inhibited Autoxidation of Tetralin

Howard¹,

Ingold²

1964

Can. J. Chem.

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The kinetics of the inhibition of the autoxidation of tctralin by 2,6-cli-l-b~it~~l-4-rneth>~l-phenol, phenol, and 4-methoxyphenol have been investigated a t 65 OC. The highly hindered 2,6-di-t-butyl-4-methylphenol follows simple hrst order kinetics and exhibits a normal tleuteriunl isotope effect ( k n / k~ = 10). 'The lcinetics with phcnol arc complicatetl by the fact that the phenoxy radical can abstract a hydrogen, ator11 from both tetralin alltl its hydroperoxide. This leads to oxidation rates which are ~nversely proportional to the square root of the phenol concentration. The tleuteri~~rn isotope efiect has about the value to be expected in view of this square root relatio~l. The Icinctics with 4-methoxyphenol result from chain transfer and from chain terminatio~l by the coupling of 4-methoxyphenoxy radicals. The isotope effect varies between zero and a value that approaches the upper limit of about 10 a t low inhibitor concentratio~~s.The inhibition of the autoxidation of styrene by phenols has been described in considerable detail in a recent series of papers from this laboratory (1). The overall process can be represented by the follo\ving simplified reaction scheme:[7 IRoc. + A' + inactive products.12 represents c~,c~'-azo-bis-isobutyronitrile (AIBN) ~v l~i c h was used to initiate the oxidations.RH represents the styrene and AH the phenolic inhibitor. The radical R' in reaction [2] represents the poly(peroxy-styryl) radical. Our experimental conditions were such that chain termination occurred predominantly by reaction [7], so that the bimolecular selftermination reaction could be ignored. Under these conditions, the theoretical rate of oxidation of the styrene is given by where p is the measured inhibited rate and e is the efficiency with which the AIBN initiates reaction chains. The correction factor (2e -l)kl[Iz] allows for oxygen absorption and nitrogen evolution by the AIBN. This equation describes the kinetics of the inhibition process with a variety of phenols a t low concentrations where self-association of the phenol by hydrogen bonding and hydrogen bonding between the phenol and the initiator were unimportant. These results in styrene differ in two important respects froin the results reported by several other worliers using basically the same technique but employing different hydrocarbon substrates. Firstly, a deuterium isotope effect ( k & / ( k~)~ = 10.6 a t 65 OC was lIsst~ed as 1V.R.C. No. 8097.

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Section: Results a N D Discussiosmentioning

confidence: 99%

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confidence: 99%

The Kinetics of the Inhibited Autoxidation of Tetralin

Howard¹,

Ingold²

1964

Can. J. Chem.

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“…For example, 1,4-benzohydroquinone at 0.03% reduced the oxidative chain length for the benzoylperoxide-initiated, uninhibited oxidation of ethyl linoleate (mole fraction of hydroquinone to ethyl linoleate 9 Â 10 À4 ) from 241 to 1 [25]. This means that in the uninhibited reaction, 241 molecules of oxygen were consumed and 241 molecules of hydroperoxide were formed in the chain reaction following the generation of one initiating radical.…”

Section: Radical Trappingmentioning

confidence: 99%

Antioxidants

Kröhnke

Schacker

Zäh

2015

Ullmann's Encyclopedia of Industrial Chemistry

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“…The semiquinones or aroxyl radicals formed are removed in pairs by disproportionation or recombination reactions. The autoxidation is thus kept under control by a chain-breaking mechanism as long as there are unchanged molecules of the antioxidant left (20,(149)(150)(151). A similar mechanism involving the radicals is probably involved in the concomitant oxidation of a number of colored organic compounds.…”

Section: Action Of Antioxidants and Their Biological Importancementioning

confidence: 99%

“…The autoxidation of methyl oleate a t temperatures between 20 and 120OC. has been investigated by Atherton and Hilditch (2) and Gunstcne and Hilditch (53).…”

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confidence: 99%