Solvent Innovations from Clariant for Safer and More Sustainable Formulations

Introduction

Solvents are fundamental components in modern agricultural formulations, playing a crucial role in ensuring the effectiveness and sustainability of crop protection products. As the agricultural industry evolves, formulators face increasing challenges in developing high-performance solutions that meet stringent regulatory requirements while maintaining environmental responsibility. The complexity of state-of-the-art agrochemical formulations, particularly Emulsifiable Concentrates (EC) or Dispersible Concentrates (DC), demands innovative approaches to solvent selection and design.

Today's agricultural practices often require the combination of multiple active ingredients (AIs) with different modes of action in a single formulation. These combinations typically include various chemical classes, and the different actives presenting distinct physicochemical characteristics and solubility profiles make the identification of suitable solvents increasingly complex.

The regulatory landscape, particularly in Europe, has significantly impacted the available toolbox of solvents over the past decade. The ban of reproductive toxicity category 1B solvents, like N-methyl-2-pyrrolidone (NMP), has created a pressing need for safer alternatives. Furthermore, the industry's growing focus on sustainability demands solvents that are biodegradable, exhibit low ecotoxicity, and demonstrate high circularity through renewable raw materials and reduced carbon footprints. Also, certain renewable resources, such as palm oil, are coming under more regulatory scrutiny as they are associated with a number of environmental and social issues, including deforestation (e.g. EU Deforestation pause Regulation EUDR in Europe) making the use of renewable feedstocks more attractive. 

Formulators must now consider multiple factors when selecting solvents: solubilization performance across various temperatures, specific physicochemical properties, regulatory compliance, and environmental impact. Additionally, practical considerations such as flash point, chemical stability, water miscibility, and packaging compatibility cannot be overlooked. Table 1 gives an overview of the desired characteristics of a good solvent. 

Table 1: Desired characteristics of good solvents

Clariant has a dedicated portfolio of water miscible and water immiscible solvents with high performance and good safety profiles, enabling the efficient development of EC, EW, SE and DC formulations (see Table 2). In the following, we highlight our most recently developed innovative solvent solutions, Genagen NBP and Genagen PA, as well as how we intend to speed up the development of new solvents in the future.

Table 2: Overview of Clariant solvents portfolio with key product characteristics

Genagen NBP – a safe water miscible solvent with high solvency power

Anticipating market needs and regulatory changes, such as the ban of NMP in Europe as well as the recently published proposed EPA ruling on an NMP ban for pesticides and other industries [1], Clariant has developed an alternative to enable formulations of NMP free products. Genagen NBP is a water miscible, aprotic polar organic solvent which provides the same outstanding solvency power as NMP and acts as a safe functional replacement. As shown in Table 3 Genagen NBP is a safe replacement for NMP without reprotoxic classification.

Table 3: Selected safety data of Genagen NBP compared to NMP.

The product shows excellent solubilization power for multiple active ingredient classes through all indications, including plant growth regulators (Figure 1).

Furthermore, Genagen NBP is suitable as the sole liquid phase, or in combination with water, in SL formulations. It is also a good co-solvent when combined with various non-water miscible solvents in EC formulations and miscible in all proportions with many typical solvents and carriers like propylene glycol, polyethylene glycol, aromatic hydrocarbons, methylated seed oil or mineral oil. 

Figure 1:  Solubility performance of Genagen NBP for a selection of active ingredients

Genagen NBP improves bioavailability of actives

With a Leica DM 4000 M microscope equipped with crossed polarizers and a DMC4500 camera, the spray deposit morphology of selected AIs was investigated using polarized light microscopy after water evaporation. The studies of the spray deposit morphology show that actives dissolved in Genagen NBP remain in a non-crystalline, amorphous state in the spray deposit after the spray water has evaporated.  As a result, Genagen NBP reduces active ingredient crystallization and the so called ″coffee ring″ phenomenon (Figure 2) which is beneficial for bioavailability.

Figure 2: Polarized light microscopy images of spray deposits of an insecticide and fungicide with and without NBP 

The positive effect of Genagen NBP on bioavailability was also studied with an advanced high-throughput cuticle penetration test available in our Clariant research facilities (see Figure 3), which measures the diffusion of actives through enzymatically isolated leaf cuticles. The droplets of the spray mixture are applied and exposed to controlled conditions of temperature (including cold) and humidity.  The penetration and interplay of actives, adjuvants and other ingredients is measured with HPLC using two 10x10 blocks per system allowing extensive testing and sufficient repetitions to overcome biological variability (further details of the used method are cited in literature [2]).

Figure 3:  Cuticular penetration setup availabe at Clariant for active penetration measurements

Figure 4:  Penetration of fungicide AI as affected by the addition of NMP and Genagen NBP

The results in Figure 4 show that Genagen NBP enhances foliar penetration, hence offering improved adjuvancy. The penetration enhancement was also observed at low temperatures (10°C, results not shown) and is concentration dependent. 

Genagen NBP a flexible solvent allowing many formulation options

Its high solubilization power for many actives and its ready miscibility with all common agrochemical solvents unlocks many options such as high-load and combo formulations. Genagen NBP can be implemented in new products across the globe due to its extensive registration status. Figure 5 displays an example of a complex DC combo formulation concept with an azole and a strobilurin fungicide. Combining selected co-formulants and an adjuvant package, the formulation provides enhanced biological performance while preventing crystal growth in the spray liquid. 

Figure 5: DC 250 g/L combo formulation concept and EC 250 g/L formulation concept

Genagen PA – a palm-free non-water miscible solvent innovation

Solvents based on palm oil derivatives, such as the well-established alkyl dimethyl amide solvents Genagen 4166 and Genagen 4296, are widely used in agrochemical formulations as they provide high solubilization power for many agrochemical actives. Yet, palm oil is also associated with several environmental and social issues, including deforestation. Anticipating market needs and regulatory changes, we have developed the palm-free alkyl dimethyl amide alternative Genagen PA. It is a palm-free solvent based on widely available pelargonic acid derived from renewable sources.  Similar to the palm-based alternatives in Clariant’s portfolio, Genagen PA is readily biodegradable and shows excellent solubilization power for a broad range of AIs as highlighted for a range of pesticide active ingredients in Table 4.

Table 4: Selected solubility data of Genagen PA for a selection of AIs

The solvent can be used in EC, EW, DC as well as SE formulations. It is easy to formulate, supports emulsion stabilization, and prevents the crystallization of actives in the formulation as well as in the spray tank, avoiding clogging of spray nozzles. An example of a formulation concept for an azole fungicide EC formulation is given in Figure 6.

Figure 6: EC 250 g/L formulation concept for Azole fungicide

In addition, Genagen PA acts as an adjuvant, improving spray retention and coverage on leaves while also enhancing the uptake of active ingredients for improved biological efficacy, as shown in the cuticular penetration measurement (method described earlier) in Figure 7.

Figure 7: Penetration of tebuconazole from a suspension concentrate Genagen PA

Digital Innovation to speed up sustainable solvent development

Clariant has developed an innovative digital platform to facilitate the transition towards safer and more sustainable solvents, recently recognized with the prestigious CEFIC responsible care award [3]. This solution integrates data mining, data integration, and visualisation technologies into a Graphical User Interface (GUI), supporting the ideation and prioritisation of chemical alternatives while avoiding regrettable substitutions.

This platform marks a significant advancement in the development of sustainable solvents by accelerating and streamlining the development process. The approach seamlessly integrates Safe and Sustainable-by-Design (SSbD) principles with advanced computational toxicology, enabling early assessment of chemical safety without extensive initial testing. 

The system's strength lies in its comprehensive data integration approach, combining chemical profiles, performance characteristics, and safety assessments through multiple data sources including public and commercial experimental databases, predictive tools, and integrated computational methods. Supporting the 3R concept (Reduction, Replacement, and Refinement of Animal Testing), it provides rapid evaluation of both existing and new innovative chemical structures and enables early-stage decision-making through data-driven hazard characterization.

For agrochemical applications specifically, it helps identify water-immiscible solvents with optimal characteristics, including a variety of physicochemical parameters, and favorable toxicity and ecotoxicity profiles (see Figure 8). 

Figure 8: Solvent Selector GUI with integrated Performance and Safety Data were allowing solvents to be visually compared to potential ″safer″ alternatives

For agrochemical formulators this means faster identification of promising solvent candidates that meet both performance requirements and sustainability criteria. The tool's ability to integrate human health and environmental indicators, while visualizing complex data, helps avoid regrettable substitutions and reduces development time and costs, ultimately accelerating the transition to more sustainable agrochemical formulations. This innovative approach positions Clariant at the forefront of sustainable solvent development, ready to meet evolving regulatory requirements and growing market demands for environmentally responsible agrochemical solutions.

Conclusion

The growing demand for sustainable agrochemical formulations requires innovative solvents that balance performance, safety, and environmental responsibility. Clariant addresses these needs with Genagen NBP, a safe water-miscible solvent offering high solvency power and enhanced bioavailability for various active ingredients, and Genagen PA, a palm-free renewable solvent which is non-water miscible and that excels in preventing active crystallization while improving spray retention and penetration. These next-generation solvents demonstrate Clariant's commitment to developing solutions that meet stringent safety and environmental standards without compromising performance. Supported by advanced digital tools, which seamlessly integrate Sustainable-by-Design (SSbD) principles with advanced computational toxicology, Clariant’s innovation process continues to accelerate the development of sustainable solvents to offer innovations for the evolving needs of the agrochemical industry.

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References: 

[1] Ref: EPA-HQ-OPPT-2020-0744 

[2] Baur P., Bodelon L., Lowe B.; 2014. A novel adjuvant blend for in-can and tank-mix application potential combining sustainability and performance as versatile penetration enhancer. In: Carmine S ed. Pesticide Formulations and Application Systems. American Society for Testing and Materials, West Conshohocken, ASTM STP 1569

[3] https://cefic.org/responsible-care/the-european-responsible-care-awards-2024-2/designing-safe-and-sustainable-products-with-digital-solutions

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