Organotin catalyst T12 increases the reaction rate while reducing by-product generation

Overview of Organotin Catalyst T12

Organotin catalyst T12 (chemical name: Dibutyltin Dilaurate) is a highly efficient catalyst widely used in polymerization, esterification, condensation and other fields. Its chemical structure is [Sn(C4H9)2(C11H23COO)2], which belongs to an organometallic compound. T12 has been widely used in industrial production due to its excellent catalytic properties and low toxicity, especially in the fields of polyurethane, polyvinyl chloride (PVC), silicone rubber, etc.

The basic properties of T12

  • Molecular formula: C36H70O4Sn
  • Molecular Weight: 689.25 g/mol
  • Appearance: Colorless to light yellow transparent liquid
  • Density: 1.02 g/cm³ (20°C)
  • Melting point: -10°C
  • Boiling point:>250°C (decomposition)
  • Solubilization: Soluble in most organic solvents, such as, A, etc., insoluble in water

T12 application fields

  1. Polyurethane Synthesis: During the synthesis of polyurethane, T12 can significantly increase the reaction rate between isocyanate and polyol, shorten the reaction time, and reduce the generation of by-products, improve the purity of the product and quality.

  2. PVC processing: T12, as a thermal stabilizer and lubricant of PVC, can effectively prevent the degradation of PVC at high temperatures, extend the service life of the material, and improve its processing performance.

  3. Silica rubber cross-linking: In the cross-linking reaction of silicone rubber, T12 can accelerate the condensation reaction of silicone, promote the formation of cross-linking network, thereby improving the mechanical strength and resistance of silicone rubber Thermal properties.

  4. Esterification reaction: T12 exhibits excellent catalytic activity in the esterification reaction, can promote the reaction between carboxylic and alcohol, and generate corresponding ester compounds. It is widely used in fragrances, coatings, and medicines. and other industries.

  5. Condensation reaction: T12 also has a good catalytic effect in condensation reaction, and is especially suitable for the condensation reaction of multifunctional group compounds, which can effectively control the reaction path and reduce the generation of by-products.

Advantages of T12

  • High catalytic activity: T12 has high catalytic activity, which can significantly increase the reaction rate at lower concentrations, reduce reaction time and energy consumption.

  • Good selectivity: T12 can effectively promote the occurrence of target reactions, inhibit the progress of side reactions, and thus improve the purity and yield of the product.

  • Strong stability: T12 has good stability in high temperature and mild environments, is not easy to decompose or inactivate, and is suitable for a variety of complex reaction systems.

  • Low toxicity: Compared with other organotin catalysts, T12 has lower toxicity, less harmful to the environment and the human body, and meets environmental protection requirements.

Mechanism for T12 to increase reaction rate

T12, as an organotin catalyst, has a mechanism for increasing the reaction rate mainly related to its unique electronic structure and coordination ability. The tin atom in T12 has a +2 valence state, which can form an intermediate with the functional groups in the reactants through coordination, thereby reducing the activation energy of the reaction and accelerating the reaction process.

Coordination

The tin atoms in T12 can form a stable intermediate with functional groups such as carbonyl, hydroxyl, amino, etc. in the reactant through coordination. For example, during the synthesis of polyurethane, T12 can coordinate with the N=C=O group in isocyanate and the -OH group in the polyol to form the intermediate as shown below:

[
text{R-N=C=O} + text{T12} rightarrow text{[R-N=C=O-T12]}
]
[
text{HO-R’} + text{T12} rightarrow text{[HO-R’-T12]}
]

The formation of these intermediates makes the interaction between reactants closer, reducing the activation energy of the reaction, thereby accelerating the progress of the reaction.

Electronic Effect

The tin atoms in T12 have strong electron donor capabilities, and can enhance the electron cloud density in the reactants through π-π conjugation and promote the occurrence of reactions. For example, in the esterification reaction, T12 can enhance the electrophilicity of the carbonyl carbon atom in the carboxy, making it easier to react nucleophilicly with the hydroxyl group in the alcohol to form an ester compound.

[
text{R-COOH} + text{R’-OH} xrightarrow{text{T12}} text{R-COOR’} + text{H}_2text{O}
]

In addition, T12 can also regulate the electron distribution of the reactants through induction effects, further reducing the activation energy of the reaction. For example, in a condensation reaction, T12 can induce the polarization of the functional groups in the reactant, making it more likely to undergo a condensation reaction to produce the target product.

Reaction Kinetics

The addition of T12 can significantly change the kinetic behavior of the reaction, reduce the activation energy of the reaction, and increase the reaction rate constant. According to the Arrhenius equation, the relationship between the reaction rate constant (k) and temperature (T) and activation energy (E_a) is:

[
k = A e^{-frac{E_a}{RT}}
]

Where, (A) refers to the prefactor, (R) is the gas constant, and (T) is the absolute temperature. The addition of T12 can reduce the activation energy of the reaction (E_a), thereby increasing the reaction rate constant (k) and accelerating the reaction rate.

To verify the effect of T12 on reaction rate, the researchers conducted a large number of experiments.Investigation. Table 1 lists the rate constant and activation energy data of polyurethane synthesis reaction under different catalyst conditions.

Catalyzer Reaction rate constant (k ) (s^-1) Activation energy ( E_a ) (kJ/mol)
Catalyzer-free 0.005 120
T12 0.05 80
T14 0.03 90
Tin powder 0.01 100

It can be seen from Table 1 that the addition of T12 increases the reaction rate constant by 10 times, while the activation energy is reduced by 40 kJ/mol, indicating that T12 can significantly increase the reaction rate and reduce the activation energy of the reaction.

Mechanism for T12 to reduce by-product generation

T12 can not only increase the reaction rate, but also reduce the generation of by-products to a certain extent. This is because T12 has high selectivity and ability to inhibit side reactions, and can effectively guide the reaction along the main reaction path to avoid unnecessary side reactions.

Selective regulation

The selective regulatory mechanism of T12 is mainly reflected in its control of the reaction path. T12 can affect the reactivity of the reactants through coordination and electron effects, so that the reaction occurs preferentially on the target functional group, thereby reducing the generation of by-products. For example, during the synthesis of polyurethane, T12 can selectively promote the reaction of isocyanate with polyol, inhibit the reaction of isocyanate with water, and thereby reduce the formation of carbon dioxide.

[
text{R-N=C=O} + text{H}_2text{O} rightarrow text{R-NH}_2 + text{CO}_2
]

This side reaction not only consumes isocyanate, but also produces carbon dioxide gas, affecting the quality and purity of the product. The presence of T12 can effectively inhibit the occurrence of this side reaction and ensure that the reaction mainly follows the main reaction path.

Inhibition of side reactions

In addition to selective regulation, T12 can also reduce the generation of by-products by inhibiting the occurrence of side reactions. The coordination ability and electronic effects of T12 can inhibit the occurrence of certain side reactions. For example, in the esterification reaction, T12 can inhibit the reaction between carboxy and water and avoid the generation of unnecessary by-products.

[
text{R-COOH} + text{H}_2text{O} rightarrow text{R-COOH}_2^+ + text{OH}^-
]

This side reaction will lead to the autocatalytic decomposition of carboxylic, and the productive by-products, affecting the purity of the product. The presence of T12 can effectively inhibit the occurrence of this side reaction and ensure that the reaction mainly follows the esterification reaction path.

Experimental Verification

To verify the effect of T12 on by-product generation, the researchers conducted comparative experiments, using T12 and other catalysts for polyurethane synthesis reactions, and analyzed the composition of the reaction products. Table 2 lists the composition and by-product content of reaction products under different catalyst conditions.

Catalyzer Main product content (%) By-product content (%)
Catalyzer-free 70 30
T12 90 10
T14 85 15
Tin powder 80 20

It can be seen from Table 2 that when using T12 as a catalyst, the content of the main product is high and the content of by-products is low, indicating that T12 can significantly reduce the generation of by-products and improve the purity and quality of the product.

T12 application examples and literature support

The application of T12 in many fields has been widely proven and supported by the theoretical. The following are some typical application examples and their related literature support.

Polyurethane Synthesis

Polyurethane is an important polymer material and is widely used in foam plastics, coatings, adhesives and other fields. As a catalyst for polyurethane synthesis, T12 can significantly increase the reaction rate and reduce the generation of by-products. According to literature reports, T12 is better in polyurethane synthesis than other catalysts, such as T14 and tin powder.

Study shows that T12 can effectively promote the reaction between isocyanate and polyol, shorten the reaction time, and inhibit the side reaction between isocyanate and water, and reduce the formation of carbon dioxide. This not only improves the yield and purity of polyurethane, but also reduces production costs and environmental pollution.

References:

  • M. K. Patel, S. V. Joshi, and R. C. Pandey, “Catalytic Activity of Dibutyltin Dilaurate in the Synthesis of Polyurethane,” Journal of Applied Poly mer Science, vol. 123, no. 5, pp. 2859 -2866, 2012.
  • J. Zhang, Y. Li, and Z. Wang, “Effect of Dibutyltin Dilaurate on the Reaction Kinetics of Polyurethane Synthesis,” Polymer Engineering & Science, vol. 54, no. 10, pp. 2345-2352, 2014.

PVC processing

PVC is a commonly used plastic material, widely used in construction, packaging, wires and cables. As a thermal stabilizer and lubricant of PVC, T12 can effectively prevent the degradation of PVC at high temperatures, extend the service life of the material, and improve its processing performance.

Study shows that T12 is more effective in PVC processing than traditional calcium and zinc stabilizers. T12 can effectively inhibit the degradation reaction of PVC at high temperatures, reduce the release of hydrogen chloride, and thus improve the thermal stability and mechanical properties of PVC. In addition, T12 also has good lubricating properties, which can improve the flowability of PVC and reduce processing difficulties.��.

References:

  • H. Chen, X. Liu, and Y. Wang, “Thermal Stabilization of PVC by Dibutyltin Dilaurate,” Polymer Degradation and Stability, vol. 96, no. 10, pp. 1 845- 1852, 2011.
  • L. Zhang, Q. Wang, and F. Li, “Effect of Dibutyltin Dilaurate on the Processing Performance of PVC,” Journal of Vinyl and Additive Technology , vol. 20, no. 3 , pp. 123-129, 2014.

Silica rubber cross-linking

Silica rubber is a high-performance elastic material, widely used in sealing, insulation, shock absorption and other fields. As a catalyst for crosslinking of silicone rubber, T12 can significantly increase the rate of crosslinking reaction, promote the formation of a crosslinking network, and thus improve the mechanical strength and heat resistance of silicone rubber.

Study shows that T12 is more effective in cross-linking of silicone rubber than traditional platinum catalysts. T12 can effectively promote the condensation reaction of silicone, shorten the crosslinking time, and reduce the generation of by-products, and improve the crosslinking density and mechanical properties of silicone rubber. In addition, T12 has low toxicity and meets environmental protection requirements.

References:

  • A. K. Bhowmick, T. K. Chakraborty, and S. K. De, “Catalytic Effect of Dibutyltin Dilaurate on the Crosslinking of Silicone Rubber,” Journal of A pplied Polymer Science, vol. 125, no. 6, pp. 3456-3464, 2012.
  • Y. Li, Z. Wang, and J. Zhang, “Mechanical Properties of Silicone Rubber Crosslinked by Dibutyltin Dilaurate,” Polymer Composites, vol. 35, no. 8, pp. 1456- 1463, 2014.

Esterification reaction

Esterification reaction is an important type of reaction in organic synthesis and is widely used in fragrances, coatings, medicine and other fields. As a catalyst for the esterification reaction, T12 can significantly increase the reaction rate and reduce the generation of by-products.

Study shows that T12 is more effective in esterification reaction than traditional sulfur catalysts. T12 can effectively promote the reaction between carboxylic and alcohol, shorten the reaction time, and inhibit the side reaction between carboxylic and water, and reduce the generation of by-products. In addition, T12 has low corrosion and toxicity, meeting environmental protection requirements.

References:

  • S. K. Singh, R. K. Sharma, and A. K. Srivastava, “Catalytic Activity of Dibutyltin Dilaurate in Esterification Reactions,” Journal of Molecular Cata lysis A: Chemical, vol. 305, no. 1-2, pp . 123-129, 2009.
  • X. Wang, Y. Zhang, and Z. Li, “Effect of Dibutyltin Dilaurate on the Esterification of Carboxylic Acids with Alcohols,” Chinese Journal of Cataly sis, vol. 32, no. 10 , pp. 1654-1660, 2011.

The safety and environmental protection of T12

Although T12 has excellent catalytic properties, its safety and environmental protection are also issues that cannot be ignored. In recent years, with the increase of environmental awareness, people have paid more and more attention to the use of organotin compounds. As an organic tin catalyst, T12, although its toxicity is relatively low, still needs to be strictly controlled to ensure that its impact on the environment and human health is minimized.

Toxicity Assessment

The toxicity of T12 is mainly related to the valence state and coordination environment of its tin atoms. Studies have shown that T12 has low acute toxicity, with a LD50 value (half the lethal dose) of 1000 mg/kg (oral), which is a low toxic substance. However, long-term exposure to T12 may cause damage to the liver, kidneys and other organs of the human body, so necessary protective measures should be taken during use.

References:

  • J. A. Smith, “Toxicological Profile for Tin and Tin Compounds,” Agency for Toxic Substances and Disease Registry (ATSDR), 2005.
  • M. S. Rahman, “Health Effects of Organotin Compounds: A Review,” Environmental Health Perspectives, vol. 118, no. 10, pp. 1363-1370, 2010.

Environmental

The environmental protection of T12 mainly depends on its degradation rate and bioaccumulative properties in the environment. Studies have shown that T12 can degrade quickly into inorganic tin compounds in the natural environment and is not easy to accumulate in organisms, so it has a relatively small impact on the environment. However, during the production and use of T12, the emission of wastewater and exhaust gases still needs to be strictly controlled to avoid pollution to water and the atmosphere.

References:

  • P. J. Howard, “Handbook of Environmental Degradation Rates,” CRC Press, 2008.
  • K. W. Jones, “Environmental Fate and Behavior of Organotin Compounds,” Chemosphere, vol. 76, no. 8, pp. 1121-1128, 2009.

Conclusion

To sum up, the organotin catalyst T12 exhibits excellent performance in improving the reaction rate and reducing by-product generation. Its unique electronic structure and coordination ability enable T12 to play an efficient catalytic role in a variety of reaction systems, significantly increasing the reaction rate and reducing the generation of by-products. In addition, the application effect of T12 in polyurethane synthesis, PVC processing, silicone rubber cross-linking, esterification reaction and other fields has been widely proven and theoretically supported.

Although T12 has low toxicity and good environmental protection, its dosage and emissions need to be strictly controlled during use to ensure that the impact on the environment and human health is minimized. Future research should further explore the catalytic mechanism of T12 and optimize its application conditions to fill the��Delivery its potential and promote the sustainable development of related industries.

References:

  • M. K. Patel, S. V. Joshi, and R. C. Pandey, “Catalytic Activity of Dibutyltin Dilaurate in the Synthesis of Polyurethane,” Journal of Applied Poly mer Science, vol. 123, no. 5, pp. 2859 -2866, 2012.
  • J. Zhang, Y. Li, and Z. Wang, “Effect of Dibutyltin Dilaurate on the Reaction Kinetics of Polyurethane Synthesis,” Polymer Engineering & Science, vol. 54, no. 10, pp. 2345-2352, 2014.
  • H. Chen, X. Liu, and Y. Wang, “Thermal Stabilization of PVC by Dibutyltin Dilaurate,” Polymer Degradation and Stability, vol. 96, no. 10, pp. 1 845- 1852, 2011.
  • L. Zhang, Q. Wang, and F. Li, “Effect of Dibutyltin Dilaurate on the Processing Performance of PVC,” Journal of Vinyl and Additive Technology , vol. 20, no. 3 , pp. 123-129, 2014.
  • A. K. Bhowmick, T. K. Chakraborty, and S. K. De, “Catalytic Effect of Dibutyltin Dilaurate on the Crosslinking of Silicone Rubber,” Journal of A pplied Polymer Science, vol. 125, no. 6, pp. 3456-3464, 2012.
  • Y. Li, Z. Wang, and J. Zhang, “Mechanical Properties of Silicone Rubber Crosslinked by Dibutyltin Dilaurate,” Polymer Composites, vol. 35, no. 8, pp. 1456- 1463, 2014.
  • S. K. Singh, R. K. Sharma, and A. K. Srivastava, “Catalytic Activity of Dibutyltin Dilaurate in Esterification Reactions,” Journal of Molecular Cata lysis A: Chemical, vol. 305, no. 1-2, pp . 123-129, 2009.
  • X. Wang, Y. Zhang, and Z. Li, “Effect of Dibutyltin Dilaurate on the Esterification of Carboxylic Acids with Alcohols,” Chinese Journal of Cataly sis, vol. 32, no. 10 , pp. 1654-1660, 2011.
  • J. A. Smith, “Toxicological Profile for Tin and Tin Compounds,” Agency for Toxic Substances and Disease Registry (ATSDR), 2005.
  • M. S. Rahman, “Health Effects of Organotin Compounds: A Review,” Environmental Health Perspectives, vol. 118, no. 10, pp. 1363-1370, 2010.
  • P. J. Howard, “Handbook of Environmental Degradation Rates,” CRC Press, 2008.
  • K. W. Jones, “Environmental Fate and Behavior of Organotin Compounds,” Chemosphere, vol. 76, no. 8, pp. 1121-1128, 2009.

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