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The properties of phenolic antioxidants
2018-1-17 11:24:44
The properties of phenolic antioxidants
The properties and structure of phenolic antioxidants are very important.
In general, the activity of the blocked phenolic antioxidant is dependent on the number and type of substituents. There have been many studies on the properties of phenolic antioxidants. Most commonly used phenolic antioxidants in industry are hindered phenolic antioxidants.
The opposite group The impact of R3. Para substituents has two functions, it is through the power of substituents increased oxygen atoms in the phenolic hydroxyl and electron cloud density, the other one is by the induced effect of para substituents to locate the registration of free electrons.
Registration of these functions to accelerate the hydroxyl substituents on the separation of hydrogen and oxygen atoms, thus improved and free radicals reaction rate constant kinh, reduces the phenol free radicals electrophilic substitution of constant, the increased free radicals to capture the number n. Scott et al. reported some for electronics groups such as methyl, tertiary butyl and methoxy replaced in phenol 2 minus 2 position, increase the antioxidant activity, while electron-withdrawing groups such as halogen, nitro or lowering hydroxy phenol antioxidant activity.
Ortho-group R1,R2's influence on the adjacent group is mainly spatial: if R1, R2 volume is larger, due to the configuration of the molecules make benzene ring with hydroxyl not in the same plane, impede oxygen P on electronics and electronic conjugate on the benzene ring, the replace phenol molecules lose stability because of the resonance effect, the result is The H on the OH is easy to escape.
When R1,If R2 is too large, it will also make free radicals difficult to deal with because of the space barrier. It is not easy to capture the effect of free radicals. These two points are contradictory. So R1 and R2 should not be too big, traditional antioxidant, R1, R2 are use t C4H9 base.
Recent studies have found that phenol hydroxyl is better than that with a methyl and a tert-butyl semi - retarded phenol structure. On the one hand, the space resistance of tert-butyl is sufficient to protect the phenolic hydroxyl group. On the other hand, the anti-oxygen reaction rate of the methyl groups on the adjacent side is faster, so the anti-oxygen activity is increased. Moreover, it has an advantage in the combination of NOx stain and sulfur-assisted antioxidant synergism.
Triphenyl phosphite (TPPi antioxidants, stabilizer) is the main raw materials of phenol, phosphorus oxychloride, phosphorus trichloride, phosphorus oxychloride, phosphorus trichloride belong to highly toxic chemicals, state control chemicals. Through raw material phenol, triclosan phosphorous and trichloride phosphorus, the direct method of trichloro phosphorus is used to direct (also known as thermal) and the indirect method of trichloride phosphorus (also known as cold method).
According to the relevant state regulations, tppi is currently exported to 9 kinds of dangerous goods.
Triphenyl phosphite (TPPi antioxidants, stabilizer) is mainly used in PVC, polyethylene, polypropylene, polystyrene, polyester, abs resin, epoxy resin, synthetic rubber antioxidant stabilizer, used in polyvinyl chloride (PVC) products as a chelating agent.
Between a substituent R4 Ingraham et al studied the influence of nearly 30 kinds of between has a substituent phenolic antioxidants, the study found that with only between a substituent phenol, no antioxidant activity, but with ortho substituents of phenolic antioxidant activity has certain influence, such as adjacent methoxy phenol itself has no antioxidant activity, but the introduction of the additional substituent such as alkoxy or amino, the phenol has good antioxidant activity. With the help of ortho-methoxyphenol, the alkoxy group showed a similar effect to the para-substituent group, and they called this effect meta-substitutional group. The second type is substituted for the base effect.
Recently, the university of Japan university of engineering has made a great victory in the university of engineering, and it has verified the anti-oxygen mechanism of a new phenolic antioxidant, namely the ortho-substituted group. The hydrogen atom on the carbon has the electron transfer of the free radical to the phenol oxygen free radical to achieve the regeneration of phenol. The elimination of electron groups on the carbon contributes to this regenerative behavior.
Based on this mechanism, the o-hydroxycinnamate compounds with acrylate group were developed. Phenolic antioxidants in short a resistance has experienced from low to high relative molecular mass, the relative molecular mass by symmetrical to the asymmetrical structure and function by a single free radicals to capture agent to adapt to a variety of occasions both heat antioxidant function, ultraviolet absorption and the transformation of the synergistic effect of composite antioxidants.
Phenolic antioxidant is a variety of anti - oxygen torture. In order to prevent or inhibit chain reaction and chain growth reaction by capturing oxygen free radicals, the free radical chain reaction is terminated. To prevent oxidation, there are hydroquinone, thiophenol, triphenol, etc.
Hydroquinone is an organic compound that is substituted by hydroxyl for two pairs of benzene. White crystals. It's called hydroquinone. Toxic, adult is wrong to take 1 gram, can appear headache, dizziness, tinnitus, complexion is pale and so on symptom. Hydroquinone is exposed to open fire, high heat and combustible, and reacts with strong oxidizer, which is released by high thermal decomposition. Hydroquinone is mainly used to make black and white imaging agents, anthraquinone dyes, azo dyes, rubber anti-aging agents, stabilizers and antioxidants.
Aniline, manganese dioxide and sulfuric acid by the mole ratio of 1:3:4 to join in the reaction kettle, when feeding should be jacketed zhongtong control of cooling water temperature under 10 ℃. Mixing reaction under 10 h, the reaction temperature gradually rose to about 25 ℃, p-benzoquinone was generated.
Then within the reactants is bubbled into water vapor water vapor distillation, steamed out of benzoquinone after partial condensation water vapor into the reduction pot, add with benzoquinone mole ratio is 1:0.7 iron powder, heating to 90 ~ 100 ℃, mixing reaction under 3 ~ 4 h, the product of the reduction reaction of hydroquinone. The reduction product was decompressed and evaporated after removing the iron oxide slag. Then add the sodium pyrosulfite, activated carbon, zinc powder, and heat to the boiling to decolorize. Strike after filtration, the filtrate slowly cooled to below 30 ℃, hydroquinone in needle crystal precipitation, after centrifugal dehydration, join ebullated bed in drying under 80 ℃, a quick hydroquinone.
Copyright: Zhang Jia Gang YaRui Chemical co.,Ltd
http://www.yaruichem.com
The properties and structure of phenolic antioxidants are very important.
In general, the activity of the blocked phenolic antioxidant is dependent on the number and type of substituents. There have been many studies on the properties of phenolic antioxidants. Most commonly used phenolic antioxidants in industry are hindered phenolic antioxidants.
The opposite group The impact of R3. Para substituents has two functions, it is through the power of substituents increased oxygen atoms in the phenolic hydroxyl and electron cloud density, the other one is by the induced effect of para substituents to locate the registration of free electrons.
Registration of these functions to accelerate the hydroxyl substituents on the separation of hydrogen and oxygen atoms, thus improved and free radicals reaction rate constant kinh, reduces the phenol free radicals electrophilic substitution of constant, the increased free radicals to capture the number n. Scott et al. reported some for electronics groups such as methyl, tertiary butyl and methoxy replaced in phenol 2 minus 2 position, increase the antioxidant activity, while electron-withdrawing groups such as halogen, nitro or lowering hydroxy phenol antioxidant activity.
Ortho-group R1,R2's influence on the adjacent group is mainly spatial: if R1, R2 volume is larger, due to the configuration of the molecules make benzene ring with hydroxyl not in the same plane, impede oxygen P on electronics and electronic conjugate on the benzene ring, the replace phenol molecules lose stability because of the resonance effect, the result is The H on the OH is easy to escape.
When R1,If R2 is too large, it will also make free radicals difficult to deal with because of the space barrier. It is not easy to capture the effect of free radicals. These two points are contradictory. So R1 and R2 should not be too big, traditional antioxidant, R1, R2 are use t C4H9 base.
Recent studies have found that phenol hydroxyl is better than that with a methyl and a tert-butyl semi - retarded phenol structure. On the one hand, the space resistance of tert-butyl is sufficient to protect the phenolic hydroxyl group. On the other hand, the anti-oxygen reaction rate of the methyl groups on the adjacent side is faster, so the anti-oxygen activity is increased. Moreover, it has an advantage in the combination of NOx stain and sulfur-assisted antioxidant synergism.
Triphenyl phosphite (TPPi antioxidants, stabilizer) is the main raw materials of phenol, phosphorus oxychloride, phosphorus trichloride, phosphorus oxychloride, phosphorus trichloride belong to highly toxic chemicals, state control chemicals. Through raw material phenol, triclosan phosphorous and trichloride phosphorus, the direct method of trichloro phosphorus is used to direct (also known as thermal) and the indirect method of trichloride phosphorus (also known as cold method).
According to the relevant state regulations, tppi is currently exported to 9 kinds of dangerous goods.
Triphenyl phosphite (TPPi antioxidants, stabilizer) is mainly used in PVC, polyethylene, polypropylene, polystyrene, polyester, abs resin, epoxy resin, synthetic rubber antioxidant stabilizer, used in polyvinyl chloride (PVC) products as a chelating agent.
Between a substituent R4 Ingraham et al studied the influence of nearly 30 kinds of between has a substituent phenolic antioxidants, the study found that with only between a substituent phenol, no antioxidant activity, but with ortho substituents of phenolic antioxidant activity has certain influence, such as adjacent methoxy phenol itself has no antioxidant activity, but the introduction of the additional substituent such as alkoxy or amino, the phenol has good antioxidant activity. With the help of ortho-methoxyphenol, the alkoxy group showed a similar effect to the para-substituent group, and they called this effect meta-substitutional group. The second type is substituted for the base effect.
Recently, the university of Japan university of engineering has made a great victory in the university of engineering, and it has verified the anti-oxygen mechanism of a new phenolic antioxidant, namely the ortho-substituted group. The hydrogen atom on the carbon has the electron transfer of the free radical to the phenol oxygen free radical to achieve the regeneration of phenol. The elimination of electron groups on the carbon contributes to this regenerative behavior.
Based on this mechanism, the o-hydroxycinnamate compounds with acrylate group were developed. Phenolic antioxidants in short a resistance has experienced from low to high relative molecular mass, the relative molecular mass by symmetrical to the asymmetrical structure and function by a single free radicals to capture agent to adapt to a variety of occasions both heat antioxidant function, ultraviolet absorption and the transformation of the synergistic effect of composite antioxidants.
Phenolic antioxidant is a variety of anti - oxygen torture. In order to prevent or inhibit chain reaction and chain growth reaction by capturing oxygen free radicals, the free radical chain reaction is terminated. To prevent oxidation, there are hydroquinone, thiophenol, triphenol, etc.
Hydroquinone is an organic compound that is substituted by hydroxyl for two pairs of benzene. White crystals. It's called hydroquinone. Toxic, adult is wrong to take 1 gram, can appear headache, dizziness, tinnitus, complexion is pale and so on symptom. Hydroquinone is exposed to open fire, high heat and combustible, and reacts with strong oxidizer, which is released by high thermal decomposition. Hydroquinone is mainly used to make black and white imaging agents, anthraquinone dyes, azo dyes, rubber anti-aging agents, stabilizers and antioxidants.
Aniline, manganese dioxide and sulfuric acid by the mole ratio of 1:3:4 to join in the reaction kettle, when feeding should be jacketed zhongtong control of cooling water temperature under 10 ℃. Mixing reaction under 10 h, the reaction temperature gradually rose to about 25 ℃, p-benzoquinone was generated.
Then within the reactants is bubbled into water vapor water vapor distillation, steamed out of benzoquinone after partial condensation water vapor into the reduction pot, add with benzoquinone mole ratio is 1:0.7 iron powder, heating to 90 ~ 100 ℃, mixing reaction under 3 ~ 4 h, the product of the reduction reaction of hydroquinone. The reduction product was decompressed and evaporated after removing the iron oxide slag. Then add the sodium pyrosulfite, activated carbon, zinc powder, and heat to the boiling to decolorize. Strike after filtration, the filtrate slowly cooled to below 30 ℃, hydroquinone in needle crystal precipitation, after centrifugal dehydration, join ebullated bed in drying under 80 ℃, a quick hydroquinone.
Copyright: Zhang Jia Gang YaRui Chemical co.,Ltd
http://www.yaruichem.com
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