News Details
Synergistic effect of antioxidants
2017-12-31 19:00:08
Synergistic effect of antioxidants
When different types of antioxidants are used, synergistic or antagonistic effects are often observed. The synergistic effect of antioxidant refers to the combination of the two effects were more than single use effect, such as phenolic antioxidant chain termination with hydrogen peroxide decomposing agent (such as Phosphite) used to improve the performance of polyolefin thermal oxidative aging has synergistic effect as everyone knows.
According to the synergistic reaction mechanism of antioxidant, it can be divided into twokinds of synergistic effects of uniformity and inhomogeneity. Synergistic effect of uniformity is two or more than two kinds of antioxidant synergy mechanism is the same but different antioxidant activity, such as two kinds of different hindered phenol ortho substituents, they are the chain termination mechanism of the same type of antioxidant, and activity of different non uniform; synergistic effect of antioxidant, such as the main and auxiliary antioxidants and.
When the 2 chain terminated antioxidants are used together, the highly active antioxidants can capture free radicals and terminate the active chain reaction. Low activity antioxidants can provide highly active antioxidants and hydrogen atoms to regenerate them.
Such as two different degrees of sterically hindered phenol, or two different structures and active amine antioxidant, or an arylamine antioxidant and a hindered phenol antioxidant and high antioxidant activity, can effectively capture the oxidation of free radicals or free radicals, which can supply the low activity of antioxidant hydrogen atom the regeneration of high activity, antioxidant, which can maintain long-term antioxidant function. The synergistic effect of the antioxidants uniformity was explained by the antioxidant mechanism of 2 different substitutions of phenol.
Hindered phenol with different steric hindrance is not difficult to see by mechanism. Peroxy radicals extract hydrogen fast from the low activity hindered phenol, and the generated phenol radical is quite active, which may participate in the chain transfer reaction. If there is a hindered phenol with a high degree of hindered reaction, it can exchange with the phenol free radical formed earlier, and produce stable phenol free radical.
The auxiliary antioxidant combined with the main antioxidant is a well known example of the synergistic effect of inhomogeneity. Peroxide decomposition agent to reduce the number of chain termination of active free radical antioxidant needs, and the same type of chain termination antioxidant peroxide decomposes burden, especially the synergistic effect of hindered phenolic antioxidant and phosphite antioxidant has been widely applied to the poly olefin antioxidant system. The reaction from the hindered phenolics and phosphite shows the effect very clearly.
The synergistic effect of hindered phenol and phosphite antioxidants can be seen intuitively by measuring the accelerated aging test of polyolefin -- the induction period of oxidation and the aging of oven.
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, when is given priority to with metal stabilizer, cooperate with this product can reduce the harm of metal chlorides, maintain product transparency, and inhibition of color change, is also a good chemical intermediates, with phosphorus-containing flame retardant and use, can play a role of flame retardant antioxidant, and with stable performance, light can be used for synthesis alkyd resin and polyester, main raw materials for resin, this product can also be preparing pesticide intermediates trimethyl phosphite.
The use of phosphite and hindered phenol antioxidants is also ideal for reducing the possible color angle of polyolefin in the use of antioxidants.
In polyolefin processing and use process, can observe the color pollution caused by the hindered phenol, this is because there are second hydrogen atoms of the benzylic carbon atom of phenolic antioxidant, it can be replaced by generating a free radical, and then the two together, formed a high conjugated quinone color in polyolefins can observed yellow hue. After adding the phosphite, the chromophore was destroyed by the coordination reaction and the Michael addition reaction, and the yellow index was reduced.
Antioxidants are a class of substances that can effectively prevent or delay automatic oxidation. They are important components of pharmaceutical excipients. They are mainly used to prevent oxidation and deterioration of drugs and their preparations, as well as the discoloration, precipitation and other aspects caused by oxidation.
The oxidation of drugs is one of the main factors that cause drug instability. The oxidative degradation of most drugs is a self oxidation process containing free radicals, in which only a small amount of oxygen can cause reaction. The oxygen in the air accounts for 21% (v/v). In the presence of so much oxygen, the drug does not need other oxidants to participate. At room temperature, it can spontaneously cause "self oxidation reaction".
The process of self oxidation is very complex. It belongs to the chain reaction induced by free radicals. Light and heat energy accelerate this reaction. Trace metal ions or peroxide will also catalyze this reaction.
In the preparation of effective components such as phenol hydroxyl or potential phenol hydroxyl in molecular structure, as long as a small amount of oxygen exists, it may cause the self oxidation reaction of the drug. The result of drug oxidation not only reduces the content of effective substances, but also changes the color of drugs, precipitates, and even produces toxic substances, which affect the quality of preparations. Therefore, in order to inhibit the effect of O2 on the oxidation reaction, it is necessary to add antioxidants.
Copyright: Zhang Jia Gang YaRui Chemical co.,Ltd
http://www.yaruichem.com
When different types of antioxidants are used, synergistic or antagonistic effects are often observed. The synergistic effect of antioxidant refers to the combination of the two effects were more than single use effect, such as phenolic antioxidant chain termination with hydrogen peroxide decomposing agent (such as Phosphite) used to improve the performance of polyolefin thermal oxidative aging has synergistic effect as everyone knows.
According to the synergistic reaction mechanism of antioxidant, it can be divided into twokinds of synergistic effects of uniformity and inhomogeneity. Synergistic effect of uniformity is two or more than two kinds of antioxidant synergy mechanism is the same but different antioxidant activity, such as two kinds of different hindered phenol ortho substituents, they are the chain termination mechanism of the same type of antioxidant, and activity of different non uniform; synergistic effect of antioxidant, such as the main and auxiliary antioxidants and.
When the 2 chain terminated antioxidants are used together, the highly active antioxidants can capture free radicals and terminate the active chain reaction. Low activity antioxidants can provide highly active antioxidants and hydrogen atoms to regenerate them.
Such as two different degrees of sterically hindered phenol, or two different structures and active amine antioxidant, or an arylamine antioxidant and a hindered phenol antioxidant and high antioxidant activity, can effectively capture the oxidation of free radicals or free radicals, which can supply the low activity of antioxidant hydrogen atom the regeneration of high activity, antioxidant, which can maintain long-term antioxidant function. The synergistic effect of the antioxidants uniformity was explained by the antioxidant mechanism of 2 different substitutions of phenol.
Hindered phenol with different steric hindrance is not difficult to see by mechanism. Peroxy radicals extract hydrogen fast from the low activity hindered phenol, and the generated phenol radical is quite active, which may participate in the chain transfer reaction. If there is a hindered phenol with a high degree of hindered reaction, it can exchange with the phenol free radical formed earlier, and produce stable phenol free radical.
The auxiliary antioxidant combined with the main antioxidant is a well known example of the synergistic effect of inhomogeneity. Peroxide decomposition agent to reduce the number of chain termination of active free radical antioxidant needs, and the same type of chain termination antioxidant peroxide decomposes burden, especially the synergistic effect of hindered phenolic antioxidant and phosphite antioxidant has been widely applied to the poly olefin antioxidant system. The reaction from the hindered phenolics and phosphite shows the effect very clearly.
The synergistic effect of hindered phenol and phosphite antioxidants can be seen intuitively by measuring the accelerated aging test of polyolefin -- the induction period of oxidation and the aging of oven.
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, when is given priority to with metal stabilizer, cooperate with this product can reduce the harm of metal chlorides, maintain product transparency, and inhibition of color change, is also a good chemical intermediates, with phosphorus-containing flame retardant and use, can play a role of flame retardant antioxidant, and with stable performance, light can be used for synthesis alkyd resin and polyester, main raw materials for resin, this product can also be preparing pesticide intermediates trimethyl phosphite.
The use of phosphite and hindered phenol antioxidants is also ideal for reducing the possible color angle of polyolefin in the use of antioxidants.
In polyolefin processing and use process, can observe the color pollution caused by the hindered phenol, this is because there are second hydrogen atoms of the benzylic carbon atom of phenolic antioxidant, it can be replaced by generating a free radical, and then the two together, formed a high conjugated quinone color in polyolefins can observed yellow hue. After adding the phosphite, the chromophore was destroyed by the coordination reaction and the Michael addition reaction, and the yellow index was reduced.
Antioxidants are a class of substances that can effectively prevent or delay automatic oxidation. They are important components of pharmaceutical excipients. They are mainly used to prevent oxidation and deterioration of drugs and their preparations, as well as the discoloration, precipitation and other aspects caused by oxidation.
The oxidation of drugs is one of the main factors that cause drug instability. The oxidative degradation of most drugs is a self oxidation process containing free radicals, in which only a small amount of oxygen can cause reaction. The oxygen in the air accounts for 21% (v/v). In the presence of so much oxygen, the drug does not need other oxidants to participate. At room temperature, it can spontaneously cause "self oxidation reaction".
The process of self oxidation is very complex. It belongs to the chain reaction induced by free radicals. Light and heat energy accelerate this reaction. Trace metal ions or peroxide will also catalyze this reaction.
In the preparation of effective components such as phenol hydroxyl or potential phenol hydroxyl in molecular structure, as long as a small amount of oxygen exists, it may cause the self oxidation reaction of the drug. The result of drug oxidation not only reduces the content of effective substances, but also changes the color of drugs, precipitates, and even produces toxic substances, which affect the quality of preparations. Therefore, in order to inhibit the effect of O2 on the oxidation reaction, it is necessary to add antioxidants.
Copyright: Zhang Jia Gang YaRui Chemical co.,Ltd
http://www.yaruichem.com
Spanish
French
Italian
Portuguese
Japanese
Korean
Arabic
Russian