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Traditional chain terminated antioxidant
2018-1-1 11:45:43
Traditional chain terminated antioxidant
Hindered phenol and aromatic secondary amine are called traditional chain terminating antioxidants, but hindered phenol will replace aromatic amine antioxidants due to the toxicity and color pollution of aromatic amines.
The traditional chain terminating antioxidants free radical trapping agents are mainly used in oxygen centered free radicals, such as alkyl peroxide radicals (ROO), alkyl oxygen free radicals (RO) and hydroxyl radicals (HO).
Because alkyl oxygen radicals and hydroxyl radicals have short life and high activity, the traditional chain terminating antioxidants quickly extract a hydrogen atom from polymer chains to form alkyl radicals, while in oxygen enriched conditions, alkyl radicals are quickly transformed into alkyl peroxide free radicals. According to the reaction mechanism, the traditional chain terminated antioxidant can be divided into two reaction mechanisms: chain terminating donor mechanism (CB-D) and chain terminating receptor mechanism (CB-A).
The mechanism of chain termination is free radical ROO, which extracts hydrogen atoms from stabilizer AH, and becomes free radical A. It also captures another peroxide radical to form a non free radical product. This kind of stabilizer has many industrial products. The typical representative is the antioxidant of the blocked phenol structure. The mechanism is as follows:
Phenol free radicals produced in this reaction is in stable state, the reaction activity of small. Through the resonance of the benzene ring, the reaction of the free radical is further transformed into a final stable structure. The antioxidants that obey the CB A mechanism can react with free radicals to form stable products that no longer cause oxidation reactions. The typical quinones react with alkyl free radicals.
Under the condition of dilute oxygen (for example, in a advanced large extruder), the traditional chain terminated antioxidant is not competent for the capture of alkyl radicals. In recent years, developed a completely new antioxidant mechanism, the so-called "pull push effect" based on it can make up for the shortcomings of traditional antioxidants, especially in dilute oxygen conditions capture alkyl radical and antioxidant and has excellent synergistic effect, can greatly improve the performance. The characteristics of these compounds are that they can capture two macromolecular radicals, the first step is the hydrogen donor and the second step is combined with the free radical of the macromolecule.
At present, this kind of carbon free radical catcher has been mixed with the traditional antioxidant of the main antioxidant as an effective antioxidant.
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.
Aromatic compounds (aromatic compounds) are a class of compounds with a benzene ring structure. They are stable, undecomposed and highly toxic. Historically, a class of aromatic compounds obtained from plant gum were called aromatic compounds. Aromatic compounds usually contain at least one benzene ring with delocalized bond in high school, but modern aromatic compounds do not contain benzene ring. Aromatic compounds have aromaticity.
Refers to the modern aromatic hydrocarbon molecules containing at least a delocalized bond of benzene ring, with unique properties and different chain compounds or alicyclic hydrocarbons (called aromatic, aromaticity) for a class of compounds. Such as benzene, naphthalene, anthracene, phenanthrene and its derivatives. Benzene is the simplest and most typical representative. They are prone to electrophilic substitution and heat more stable, mainly from petroleum and coal tar.
Some molecules although not containing benzene but also with aromatic compounds with similar benzene, called non benzene aromatic compounds, such as salt, grass azulene etc.. The organic compounds containing the benzene ring in the molecule are called aromatic compounds. It includes aromatic hydrocarbons and their derivatives, such as halogenated aromatic hydrocarbons, aromatic nitro compounds, aromatic alcohols, aromatic acids, steroids, and so on.
It was originally a compound containing a benzene ring in a molecule. In the middle of nineteenth Century, chemical workers found that quite a lot of organic compounds had some special properties. Their ratio of hydrogen atoms to carbon atoms was often less than 1, but their chemical properties were not like general unsaturated compounds. For example, they are not easy to react and are easy to replace. Many of these compounds are fragrant and some are extracted from spices, so they are called aromatic compounds. It is later found that aromatic compounds are derivatives of one or more hydrogen atoms in the benzene molecule that are replaced by other atoms or atomic groups.
Some compounds can be regarded as polycyclic systems which are connected by benzene through two or more than two carbon atoms. They also belong to aromatic compounds, such as naphthalene and anthracene. After 1930s, the meaning of aromatic compounds has been further developed. Some compounds do not contain benzene ring, but have some properties of aromatic compounds. For example, phenols and two ferrocene can take place substitution reactions. These compounds are non benzene aromatic compounds.
Other compounds can be judged to have aromaticity according to the shock rule. The specific expression is for fully conjugated, single ring, planar multi double bond matter, and has (4n+2) a delocalized pi electron (n here is an integer greater than or equal to zero), which may have a special aromatic stability. Therefore, heterocyclic substances like pyridine are all aromatic. Their derivatives are also aromatic compounds.
Copyright: Zhang Jia Gang YaRui Chemical co.,Ltd
http://www.yaruichem.com
Hindered phenol and aromatic secondary amine are called traditional chain terminating antioxidants, but hindered phenol will replace aromatic amine antioxidants due to the toxicity and color pollution of aromatic amines.
The traditional chain terminating antioxidants free radical trapping agents are mainly used in oxygen centered free radicals, such as alkyl peroxide radicals (ROO), alkyl oxygen free radicals (RO) and hydroxyl radicals (HO).
Because alkyl oxygen radicals and hydroxyl radicals have short life and high activity, the traditional chain terminating antioxidants quickly extract a hydrogen atom from polymer chains to form alkyl radicals, while in oxygen enriched conditions, alkyl radicals are quickly transformed into alkyl peroxide free radicals. According to the reaction mechanism, the traditional chain terminated antioxidant can be divided into two reaction mechanisms: chain terminating donor mechanism (CB-D) and chain terminating receptor mechanism (CB-A).
The mechanism of chain termination is free radical ROO, which extracts hydrogen atoms from stabilizer AH, and becomes free radical A. It also captures another peroxide radical to form a non free radical product. This kind of stabilizer has many industrial products. The typical representative is the antioxidant of the blocked phenol structure. The mechanism is as follows:
Phenol free radicals produced in this reaction is in stable state, the reaction activity of small. Through the resonance of the benzene ring, the reaction of the free radical is further transformed into a final stable structure. The antioxidants that obey the CB A mechanism can react with free radicals to form stable products that no longer cause oxidation reactions. The typical quinones react with alkyl free radicals.
Under the condition of dilute oxygen (for example, in a advanced large extruder), the traditional chain terminated antioxidant is not competent for the capture of alkyl radicals. In recent years, developed a completely new antioxidant mechanism, the so-called "pull push effect" based on it can make up for the shortcomings of traditional antioxidants, especially in dilute oxygen conditions capture alkyl radical and antioxidant and has excellent synergistic effect, can greatly improve the performance. The characteristics of these compounds are that they can capture two macromolecular radicals, the first step is the hydrogen donor and the second step is combined with the free radical of the macromolecule.
At present, this kind of carbon free radical catcher has been mixed with the traditional antioxidant of the main antioxidant as an effective antioxidant.
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.
Aromatic compounds (aromatic compounds) are a class of compounds with a benzene ring structure. They are stable, undecomposed and highly toxic. Historically, a class of aromatic compounds obtained from plant gum were called aromatic compounds. Aromatic compounds usually contain at least one benzene ring with delocalized bond in high school, but modern aromatic compounds do not contain benzene ring. Aromatic compounds have aromaticity.
Refers to the modern aromatic hydrocarbon molecules containing at least a delocalized bond of benzene ring, with unique properties and different chain compounds or alicyclic hydrocarbons (called aromatic, aromaticity) for a class of compounds. Such as benzene, naphthalene, anthracene, phenanthrene and its derivatives. Benzene is the simplest and most typical representative. They are prone to electrophilic substitution and heat more stable, mainly from petroleum and coal tar.
Some molecules although not containing benzene but also with aromatic compounds with similar benzene, called non benzene aromatic compounds, such as salt, grass azulene etc.. The organic compounds containing the benzene ring in the molecule are called aromatic compounds. It includes aromatic hydrocarbons and their derivatives, such as halogenated aromatic hydrocarbons, aromatic nitro compounds, aromatic alcohols, aromatic acids, steroids, and so on.
It was originally a compound containing a benzene ring in a molecule. In the middle of nineteenth Century, chemical workers found that quite a lot of organic compounds had some special properties. Their ratio of hydrogen atoms to carbon atoms was often less than 1, but their chemical properties were not like general unsaturated compounds. For example, they are not easy to react and are easy to replace. Many of these compounds are fragrant and some are extracted from spices, so they are called aromatic compounds. It is later found that aromatic compounds are derivatives of one or more hydrogen atoms in the benzene molecule that are replaced by other atoms or atomic groups.
Some compounds can be regarded as polycyclic systems which are connected by benzene through two or more than two carbon atoms. They also belong to aromatic compounds, such as naphthalene and anthracene. After 1930s, the meaning of aromatic compounds has been further developed. Some compounds do not contain benzene ring, but have some properties of aromatic compounds. For example, phenols and two ferrocene can take place substitution reactions. These compounds are non benzene aromatic compounds.
Other compounds can be judged to have aromaticity according to the shock rule. The specific expression is for fully conjugated, single ring, planar multi double bond matter, and has (4n+2) a delocalized pi electron (n here is an integer greater than or equal to zero), which may have a special aromatic stability. Therefore, heterocyclic substances like pyridine are all aromatic. Their derivatives are also aromatic compounds.
Copyright: Zhang Jia Gang YaRui Chemical co.,Ltd
http://www.yaruichem.com
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