Advanced Applications of DBU p-Toluenesulfonate (CAS 51376-18-2) in Polymer Science

Introduction

DBU p-toluenesulfonate, also known as 1,8-Diazabicyclo[5.4.0]undec-7-ene p-toluenesulfonate, is a versatile compound with a wide range of applications in polymer science. This salt of the strong organic base DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) and p-toluenesulfonic acid has gained significant attention due to its unique properties and potential in various polymerization processes. In this comprehensive article, we will delve into the advanced applications of DBU p-toluenesulfonate, exploring its role in polymer synthesis, catalysis, and material science. We will also provide detailed product parameters, compare it with other similar compounds, and reference relevant literature to ensure a thorough understanding of this fascinating chemical.

Product Parameters

Chemical Structure and Properties

Parameter	Value
Chemical Name	1,8-Diazabicyclo[5.4.0]undec-7-ene p-toluenesulfonate
CAS Number	51376-18-2
Molecular Formula	C19H22N2O3S
Molecular Weight	366.45 g/mol
Appearance	White to off-white crystalline powder
Melting Point	165-167°C
Solubility	Soluble in water, ethanol, and other polar solvents
pH (1% solution)	8.5-9.5
Storage Conditions	Store in a cool, dry place, away from moisture and heat
Shelf Life	2 years when stored properly

Safety Information

Hazard Statement	Precautionary Statement
H302: Harmful if swallowed	P264: Wash skin thoroughly after handling.
H312: Harmful in contact with skin	P270: Do not eat, drink or smoke when using this product.
H315: Causes skin irritation	P280: Wear protective gloves/protective clothing/eye protection/face protection.
H319: Causes serious eye irritation	P301 + P312: IF SWALLOWED: Call a POISON CENTER or doctor/physician if you feel unwell.
H332: Harmful if inhaled	P302 + P352: IF ON SKIN: Wash with plenty of soap and water.
H335: May cause respiratory irritation	P305 + P351 + P338: IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.

Physical and Chemical Properties

DBU p-toluenesulfonate is a white to off-white crystalline powder that is highly soluble in water and polar organic solvents such as ethanol. Its molecular structure consists of a bicyclic amine (DBU) and a p-toluenesulfonate group, which gives it both basic and acidic functionalities. The compound has a melting point of 165-167°C, making it suitable for high-temperature reactions. Its pH in a 1% aqueous solution ranges from 8.5 to 9.5, indicating that it is a moderately basic compound.

Comparison with Other Compounds

Compound	Molecular Weight	Solubility	pH (1% Solution)	Applications
DBU p-Toluenesulfonate	366.45 g/mol	Water, Ethanol	8.5-9.5	Polymerization, Catalysis, Material Science
DBU Hydrochloride	242.77 g/mol	Water, Ethanol	6.5-7.5	Acidic Catalysts, Organic Synthesis
DBU Carbonate	326.38 g/mol	Water, Ethanol	9.0-10.0	Base Catalysts, Polymer Crosslinking
Triethylamine p-Toluenesulfonate	285.38 g/mol	Water, Ethanol	8.0-9.0	Phase Transfer Catalyst, Polymerization

As shown in the table above, DBU p-toluenesulfonate has a higher molecular weight than DBU hydrochloride and triethylamine p-toluenesulfonate, which can affect its solubility and reactivity. Its pH is slightly more basic than DBU hydrochloride but less basic than DBU carbonate, making it a versatile compound for both acidic and basic reactions.

Applications in Polymer Science

1. Initiator for Anionic Polymerization

Anionic polymerization is a powerful technique for producing well-defined polymers with narrow molecular weight distributions. DBU p-toluenesulfonate has been widely used as an initiator for anionic polymerization due to its ability to generate active species under mild conditions. The presence of the p-toluenesulfonate group helps to stabilize the anionic intermediate, leading to more controlled polymer growth.

Example: Polystyrene Synthesis

In one study, DBU p-toluenesulfonate was used to initiate the anionic polymerization of styrene. The reaction was carried out at room temperature in tetrahydrofuran (THF) with a small amount of water as a co-initiator. The resulting polystyrene had a polydispersity index (PDI) of 1.1, indicating excellent control over the polymerization process. The use of DBU p-toluenesulfonate allowed for the preparation of high-molecular-weight polystyrene with precise chain lengths, which is crucial for applications in coatings, adhesives, and electronic materials.

Literature Reference:

Moad, G., & Solomon, D. H. (2006). The Chemistry of Radical Polymerization. Elsevier.
Matyjaszewski, K., & Davis, T. P. (2002). Handbook of Radical Polymerization. John Wiley & Sons.

2. Catalyst for Ring-Opening Polymerization (ROP)

Ring-opening polymerization (ROP) is a widely used method for synthesizing biodegradable polymers, such as polylactide (PLA) and polyglycolide (PGA). DBU p-toluenesulfonate has emerged as an efficient catalyst for ROP due to its strong basicity and ability to activate cyclic monomers. The p-toluenesulfonate group helps to stabilize the transition state, leading to faster and more selective polymerization.

Example: Polylactide Synthesis

In a recent study, DBU p-toluenesulfonate was used to catalyze the ring-opening polymerization of lactide. The reaction was performed at 130°C in the absence of solvent, and the resulting polylactide had a high molecular weight (Mn = 50,000 g/mol) and a narrow PDI of 1.2. The use of DBU p-toluenesulfonate allowed for the preparation of polylactide with excellent thermal stability and mechanical properties, making it suitable for biomedical applications such as drug delivery and tissue engineering.

Literature Reference:

Albertsson, A.-C. (2003). Degradable Aliphatic Polyesters. Springer.
Loh, X. J., & Teo, W. S. (2004). Progress in Polymer Science, 29(1), 1-26.

3. Crosslinking Agent for Thermosetting Polymers

Thermosetting polymers are widely used in industries such as automotive, aerospace, and construction due to their excellent mechanical properties and thermal stability. DBU p-toluenesulfonate has been explored as a crosslinking agent for thermosetting polymers, particularly epoxy resins. The compound undergoes a two-step reaction: first, it deprotonates the epoxy groups, and then it facilitates the formation of crosslinks between the polymer chains.

Example: Epoxy Resin Crosslinking

In a study by Zhang et al. (2018), DBU p-toluenesulfonate was used as a crosslinking agent for diglycidyl ether of bisphenol A (DGEBA) epoxy resin. The cured epoxy resin exhibited a significantly higher glass transition temperature (Tg) compared to the uncrosslinked resin, indicating enhanced thermal stability. Additionally, the crosslinked epoxy resin showed improved mechanical properties, including increased tensile strength and modulus. The use of DBU p-toluenesulfonate as a crosslinking agent offers a simple and effective way to enhance the performance of thermosetting polymers.

Literature Reference:

Zhang, Y., Li, J., & Wang, X. (2018). Journal of Applied Polymer Science, 135(15), 46344.
Mark, J. E. (2001). Physical Properties of Polymers Handbook. Springer.

4. Additive for Controlled Radical Polymerization (CRP)

Controlled radical polymerization (CRP) techniques, such as atom transfer radical polymerization (ATRP) and reversible addition-fragmentation chain transfer (RAFT) polymerization, have revolutionized the field of polymer chemistry by allowing for the synthesis of polymers with well-defined architectures. DBU p-toluenesulfonate has been investigated as an additive in CRP processes, where it serves as a base to regenerate the active radical species and maintain control over the polymerization.

Example: RAFT Polymerization of Methyl Methacrylate

In a study by Hawker et al. (2001), DBU p-toluenesulfonate was used as an additive in the RAFT polymerization of methyl methacrylate (MMA). The presence of DBU p-toluenesulfonate led to a more controlled polymerization, with a narrower PDI and higher conversion rates compared to the control experiment without the additive. The use of DBU p-toluenesulfonate in CRP processes offers a promising approach to achieving better control over polymer architecture and properties.

Literature Reference:

Hawker, C. J., & Wooley, K. L. (2001). Macromolecules, 34(21), 7248-7251.
Chiefari, J., Chong, Y. K., Ercole, F., Krstina, J., Lamberti, A., Mayo, F., … & Solomon, D. H. (1998). Macromolecules, 31(19), 6501-6513.

5. Modifier for Surface Functionalization

Surface functionalization is a critical step in the development of advanced polymer-based materials, such as coatings, membranes, and biomedical devices. DBU p-toluenesulfonate has been used as a modifier to introduce reactive groups onto the surface of polymers, enabling further chemical modifications or interactions with other materials.

Example: Surface Modification of Polyethylene

In a study by Kim et al. (2017), DBU p-toluenesulfonate was used to modify the surface of polyethylene (PE) films. The modified PE films were then subjected to grafting reactions with acrylic acid, resulting in the formation of carboxylic acid groups on the surface. The presence of these functional groups allowed for the attachment of biomolecules, such as antibodies and enzymes, making the modified PE films suitable for biosensing applications. The use of DBU p-toluenesulfonate as a surface modifier offers a simple and effective way to tailor the properties of polymer surfaces for specific applications.

Literature Reference:

Kim, J., Park, S., & Lee, S. (2017). Langmuir, 33(12), 3055-3062.
Bhatia, S. K., & Hills, G. A. (1991). Polymer Surfaces and Interfaces: Characterization, Modification, and Applications. Springer.

Conclusion

DBU p-toluenesulfonate (CAS 51376-18-2) is a versatile compound with a wide range of applications in polymer science. Its unique combination of basicity and acidity, along with its excellent solubility and thermal stability, makes it an ideal choice for various polymerization processes, including anionic polymerization, ring-opening polymerization, and controlled radical polymerization. Additionally, DBU p-toluenesulfonate has shown promise as a crosslinking agent for thermosetting polymers and a modifier for surface functionalization.

As research in polymer science continues to advance, the demand for efficient and versatile reagents like DBU p-toluenesulfonate is likely to grow. By exploring new applications and optimizing existing ones, scientists and engineers can unlock the full potential of this remarkable compound and develop innovative polymer-based materials for a wide range of industries.

In summary, DBU p-toluenesulfonate is not just a chemical; it’s a key player in the world of polymer science, opening doors to new possibilities and pushing the boundaries of what we can achieve with polymers. Whether you’re working on cutting-edge biomedical materials or developing the next generation of high-performance coatings, DBU p-toluenesulfonate is a tool worth considering. So, why not give it a try? After all, as they say in the world of chemistry, "sometimes, a little salt can make all the difference." 🧪

References:

Moad, G., & Solomon, D. H. (2006). The Chemistry of Radical Polymerization. Elsevier.
Matyjaszewski, K., & Davis, T. P. (2002). Handbook of Radical Polymerization. John Wiley & Sons.
Albertsson, A.-C. (2003). Degradable Aliphatic Polyesters. Springer.
Loh, X. J., & Teo, W. S. (2004). Progress in Polymer Science, 29(1), 1-26.
Zhang, Y., Li, J., & Wang, X. (2018). Journal of Applied Polymer Science, 135(15), 46344.
Mark, J. E. (2001). Physical Properties of Polymers Handbook. Springer.
Hawker, C. J., & Wooley, K. L. (2001). Macromolecules, 34(21), 7248-7251.
Chiefari, J., Chong, Y. K., Ercole, F., Krstina, J., Lamberti, A., Mayo, F., … & Solomon, D. H. (1998). Macromolecules, 31(19), 6501-6513.
Kim, J., Park, S., & Lee, S. (2017). Langmuir, 33(12), 3055-3062.
Bhatia, S. K., & Hills, G. A. (1991). Polymer Surfaces and Interfaces: Characterization, Modification, and Applications. Springer.