Hydrogenation Reactions

Safe Reaction Monitoring at Elevated Temperature and Pressure

Hydrogenation reactions are among the most important reaction classes in the production of both bulk and fine chemicals. When adding hydrogen atoms to an organic compound, double or triple bonds are reduced to single bonds. This reduction enables the formation of C—C single bonds from alkenes and alkynes, C—O bonds from ketones, aldehydes, or esters, and C—N bonds (amines) from imines or nitriles.

medical gloves holding beaker of vegetable oil

Hydrogenation of Nitrobenzene

Application Note

Data-rich experimentation brings the maximum amount of information, resulting in fewer experiments. This efficiency helps identify the relationships between a wide range of reaction parameters and leads to greater process understanding.

Reaction calorimetry used in conjunction with in-situ process analytical technology (PAT) helps identify the optimal operating conditions of a chemical process by combining knowledge of kinetic and thermodynamic parameters.

1. Reduction Hydrogenation

This type of hydrogenation involves the reduction of a compound with hydrogen. For example, an alkene can be reduced to an alkane by adding hydrogen atoms to the double bond.

2. Hydrogenolysis

This type of hydrogenation involves the cleavage of a chemical bond in a molecule using hydrogen. For example, an ester can be hydrolyzed to an alcohol and a carboxylic acid by adding hydrogen atoms across the C—O bond.

3. Catalytic Hydrogenation

This type of hydrogenation is a key process in the chemical and pharmaceutical industries, crucial for the efficient reduction of alkenes.

This video offers an in-depth overview of the fundamental principles, essential techniques, and critical reaction parameters, including temperature, pressure, catalyst selection, and hydrogen feed rate, that must be precisely controlled to optimize reaction rate, selectivity, and yield.

Discover how real-time monitoring and process analytical technology (PAT) can help overcome common challenges such as managing intermediate and byproduct formation, while ensuring process safety and product quality. ReactIR, and other in-situ tools, can enhance process understanding, enabling confident, data-driven optimization of your hydrogenation applications.

Single bonds form by adding hydrogen atoms to an organic compound with double or triple-bond functionality. Examples of hydrogenation reaction products that form in a single step include:

C—C single bonds from alkenes and alkynes
C—O bonds from ketones, aldehydes, or esters
C—N bonds (amines) from imines or nitriles

Metal catalysts are often used in hydrogenation reactions to reduce the high energy barrier of the transformation and are often referred to as a catalytic hydrogenation. For example, alkenes and alkynes require a nickel, palladium, or platinum catalyst to transform into alkanes. Hydrogenation reactions can be homogenous or heterogeneous when using metals adsorbed on various substrates. For example, to achieve homogeneous asymmetric hydrogenation, specific ligands are coordinated with rhodium and iridium metal catalysts.

In all cases, the choice of the catalyst greatly influences a hydrogenation reaction. Factors of the catalyst that impact the hydrogenation reaction include the catalyst concentration, solvent, substrate purity, temperature, and pressure.

Industry Examples and Commercial Applications of Hydrogenation

Fine Chemicals: Tracking Exothermic Hydrogenation Steps With RC1

Delgado, J., Salcedo, W. N. V., Devouge-Boyer, C., Hebert, J., Legros, J., Renou, B., Held, C., Grenman, H., & Leveneur, S. (2023). Reaction enthalpies for the hydrogenation of alkyl levulinates and levulinic acid on Ru/C– influence of experimental conditions and alkyl chain length. Chemical Engineering Research & Design, 171, 289–298. https://doi.org/10.1016/j.psep.2023.01.025

This example presents a study on how to optimize catalysts for batch hydrogenation reactions using automated high-throughput experimentation. The authors describe how they used a combination of ReactIR™ in-situ FTIR spectroscopy and RC1 high-pressure reaction calorimeter to monitor and control the hydrogenation process and perform in-situ measurements of reaction kinetics and product formation.

The study showed that the automated high-throughput experimentation approach with METTLER TOLEDO instruments can significantly improve the efficiency and accuracy of catalyst optimization for batch hydrogenation reactions. The authors noted that the use of ReactIR and RC1 reactor control unit enabled real-time monitoring of the reaction, which facilitated the identification of optimal catalyst conditions based on reaction kinetics and product formation. The use of FTIR and reaction calorimetry instruments for optimizing hydrogenation processes and catalysts led to faster and more efficient reaction optimization in batch hydrogenation.

Fine Chemicals: Efficient Hydrogenation Catalyst Screening Using In-Situ FTIR

Baimuratova, R. K., Andreeva, A. V., Uflyand, I. E., Shilov, G. V., Bukharbayeva, F. U., Zharmagambetova, A. K., & Dzhardimalieva, G. I. (2022). Synthesis and Catalytic Activity in the Hydrogenation Reaction of Palladium-Doped Metal-Organic Frameworks Based on Oxo-Centered Zirconium Complexes. Journal of Composites Science, 6(10), 299. https://doi.org/10.3390/jcs6100299

The authors describe the use of METTLER TOLEDO instruments such as the EasyMax automated reactor system and in-situ FTIR probe for real-time monitoring of hydrogenation reactions. They also discuss the integration of a robotic platform to automate the process of reaction screening, allowing for high-throughput optimization of reaction conditions.

Automated platforms help reduce the time and resources required for optimizing hydrogenation reactions, as well as improving the efficiency and accuracy of the process. The use of in-situ FTIR spectroscopy instruments in combination with the automated platform provides a reliable and efficient method for screening and developing hydrogenation reactions.

Pharmaceutical: Asymmetric Transfer Hydrogenation

Zhang, Y., Yuan, M., Liu, W., Xie, J., & Zhou, Q. (2018). Iridium-Catalyzed asymmetric transfer hydrogenation of alkynyl ketones using sodium formate and ethanol as hydrogen sources. Organic Letters, 20(15), 4486–4489. https://doi.org/10.1021/acs.orglett.8b01787

This example describes a new method for the asymmetric transfer hydrogenation of alkynyl ketones using iridium catalysts. The authors discuss the use ReactIR spectrometer to monitor the progress of the reaction in real time, allowing them to optimize the reaction conditions and monitor the reaction intermediates. The use of EasyMax™ reactor system for the reaction setup allowed for precise control of the reaction parameters such as temperature and stirring speed.

The combination of the in-situ reaction monitoring instruments with the iridium catalyst system enabled the researchers to perform the reaction with high reproducibility and accuracy. This approach could be extended to other catalytic reactions, allowing for more efficient and accurate reaction optimization and analysis.

Safety and Environmental Considerations

There are several risks associated with hydrogenation reactions, including:

Explosion hazard: Hydrogen gas is highly flammable and can cause explosions if it accumulates in confined spaces.
Fire hazard: Hydrogenation reactions can generate heat, which can cause fires if not properly controlled.
Toxicity: Some hydrogenation catalysts, such as nickel, can be toxic if inhaled or ingested.
Environmental impact: Hydrogenation reactions can produce waste products that can harm the environment if not properly disposed of.
Health risks: Certain hydrogenated products, such as hydrogenated vegetable oils, have been linked to an increased risk of heart disease.
Safety risks: Hydrogenation reactions can be exothermic and generate heat during the process, which can cause thermal runaway if not properly controlled.
Handling of the reagents: Catalysts and intermediates must be handled carefully as they can be corrosive, toxic, flammable, and reactive. It is important to note that these risks can be mitigated by following proper safety protocols and using appropriate equipment and materials.

Environmental Impact of Hydrogenation

Hydrogenation reactions can have potential environmental impacts due to the use of catalysts and solvents, which can generate waste and potentially harm the environment. To alleviate these potential environmental impacts, scientists are now utilizing chemical reaction modeling and simulation software to reduce the use of hazardous materials. By using computer simulations, engineers can predict the outcome of the reaction and optimize the conditions to minimize waste and reduce the use of harmful chemicals.

Additionally, reaction modeling can be used to identify alternative, more environmentally friendly catalysts, and solvents, which can further reduce the impact of the reaction on the environment. By using chemical reaction modeling to design and optimize hydrogenation reactions, it is possible to minimize waste and reduce the environmental impact while maintaining or improving the efficiency and cost of the reaction.

Hydrogenation catalyst screening is a crucial step in the development of a successful hydrogenation reaction. It involves evaluating various catalysts to determine the most efficient and effective one for a specific reaction. During the screening process, factors such as the rate of reaction, selectivity, and stability of the catalyst are considered to select the best one.

The screening process typically involves conducting a series of experiments with different catalysts, evaluating the results, and making comparisons to determine the most suitable catalyst. In addition to traditional catalysts like nickel and palladium, other catalysts such as rhodium, iridium, and ruthenium can also be evaluated. The outcome of the hydrogenation catalyst screening process is important because it directly impacts the efficiency, cost, and overall success of the hydrogenation reaction.

Catalyst Selection

Another challenge with hydrogenation reactions is achieving the desired degree of selectivity, or the ability to selectively hydrogenate certain bonds or molecular functional groups while leaving others unreacted. This can be difficult, especially when the molecule contains multiple bonds or functional groups that can be hydrogenated.

In-situ FTIR spectroscopy is an analytical technique that provides instantaneous information and enables actionable decisions to be made in real time. FTIR probe technology, such as ReactIR, is impervious to solid particles, gases, and most reaction conditions, and offers advantages over alternative offline analytical methods with the ability to:

Investigate homogeneous and heterogeneous hydrogenations under actual reaction conditions, including at elevated pressure and temperature
Identify, track, and measure reactants, reagents, products, reaction intermediates, and byproducts produced in hydrogenations
Rapidly acquire data-rich information for determining reaction kinetics and understanding reaction mechanisms and pathways
Test and develop ideal hydrogenation conditions for optimizing end-product yield and minimizing side products
Quickly screen catalysts and conditions for specific hydrogenation reactions
Eliminate the introduction of air, moisture, or disturbing reaction equilibria resulting from sample extraction

Learn more about in-situ FTIR spectroscopy

Another challenge with hydrogenation reactions is catalyst deactivation or the loss of catalytic activity over time. This can be caused by various factors, such as the poisoning of the catalyst by impurities in the reactants or by-products, or by sintering (the formation of a solid mass) of the catalyst. The use of a probe-based automated sampling system provides representative reaction samples over extended periods, even under pressure.

Pressure Control

Hydrogenation reactions are typically carried out under high pressure, which can be dangerous and cause equipment to fail, potentially leading to accidents and injuries. As such, it is important to carefully control the pressure during the reaction to ensure that it remains within a safe and consistent range.

Appropriate safety measures should be in place to protect workers and equipment. This includes the use of pressure-rated equipment, such as reactors and piping, as well as safety devices like pressure relief valves and pressure gauges.

Learn more about lab-scale high pressure reactors

Hydrogenation Reaction pressure management

Heat Management

Hydrogenation reactions are exothermic, meaning that they release heat. Managing the heat of reaction can be challenging, as excessive heat can cause problems such as thermal runaway (a rapid increase in temperature) or decomposition of the reactants.

Reaction calorimetry is used to identify thermodynamic and kinetic parameters, which are crucial for the design and optimization of chemical processes and safety evaluations.

High-accuracy calorimetric measurements under pressure are essential for trustworthy and reliable data for process safety evaluations.

Inaccurate calorimetry results might lead to:

Lack of understanding of accurate thermochemistry data
Risk of accidents and personnel injuries
No trust in data - plant cannot run in an optimal way
Environmental consequences
Monetary and reputation loss

Learn more about reaction calorimetry

Additional Resources

Catalytic Hydrogenation of Nitrobenzene to Aniline

This application note outlines the reduction of nitrobenzene using a commercially available catalyst...

Endpoint Detection of a Hydrogenation

Automated sampling of a hydrogenation at 5 bar pressure improved product quality by enabling the stu...

Tandem Hydroformylation/Hydrogenation of Alkenes

Real time, in-situ mid-FTIR reaction monitoring leads to a greater understanding of catalyst activit...

Acid Catalyzed Transfer Hydrogenation

Asymmetric organocatalytic hydrogenation of benzoxazines in continuous-flow microreactors as a metal...

Avoid By-Product Formation in Hydrogenation

This white paper discusses the root cause of by-product formation in a hydrogenation reaction. and h...

Examples of Reaction Control, Analysis, and Modeling to Drive Green Chemistry and Sustainable Development

Drive sustainable development through green chemistry practices by achieving efficiency and reducing...

Guide to Chemical Process Safety

Guide to Process Safety discusses challenges to consider when designing a safe process including the...

Reaction Calorimetry Guide

Minimize risks and ensure the safety of your lab and personnel. Our guide covers all aspects of reac...

Development of a Transfer Hydrogenation Controlled by Nitrogen Flow

In this presentation, we review the development of Belzutifan and how the Merck team applied concept...

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Hydrogenation Reaction Monitoring in Peer-Reviewed Publications

Delgado, J., Salcedo, W. N. V., Devouge-Boyer, C., Hebert, J., Legros, J., Renou, B., Held, C., Grenman, H., & Leveneur, S. (2023). Reaction enthalpies for the hydrogenation of alkyl levulinates and levulinic acid on Ru/C– influence of experimental conditions and alkyl chain length. Chemical Engineering Research & Design, 171, 289–298. https://doi.org/10.1016/j.psep.2023.01.025
Baimuratova, R. K., Andreeva, A. V., Uflyand, I. E., Shilov, G. V., Bukharbayeva, F. U., Zharmagambetova, A. K., & Dzhardimalieva, G. I. (2022). Synthesis and Catalytic Activity in the Hydrogenation Reaction of Palladium-Doped Metal-Organic Frameworks Based on Oxo-Centered Zirconium Complexes. Journal of Composites Science, 6(10), 299. https://doi.org/10.3390/jcs6100299
Wheelhouse, K. M. P., Fenner, S., & Whiting, M. (2022). Application of High-Throughput experimentation in identification of conditions for selective nitro group hydrogenation. In Acs Symposium Series (pp. 79–91). https://doi.org/10.1021/bk-2022-1420.ch005
Zhang, Y., Yuan, M., Liu, W., Xie, J., & Zhou, Q. (2018). Iridium-Catalyzed asymmetric transfer hydrogenation of alkynyl ketones using sodium formate and ethanol as hydrogen sources. Organic Letters, 20(15), 4486–4489. https://doi.org/10.1021/acs.orglett.8b01787 https://doi.org/10.1021/acs.orglett.8b01787
Ehnes, C., Lucas, M., & Claus, P. (2016). In‐situ ATR‐IR Spectroscopy: Monitoring Hydrogenation of CO2 and Formation of Formic Acid. Chemie Ingenieur Technik, 88(10), 1474–1479. https://doi.org/10.1002/cite.201600031
Liu, W., Yuan, M., Yang, X., Ke, L., Xie, J., & Zhou, Q. (2015). Efficient asymmetric transfer hydrogenation of ketones in ethanol with chiral iridium complexes of spiroPAP ligands as catalysts. Chemical Communications, 51(28), 6123–6125. https://doi.org/10.1039/c5cc00479a
Hamilton, P., Sanganee, M. J., Graham, J., Hartwig, T., Ironmonger, A., Priestley, C., A, L., Senior, Thompson, D. R., & Webb, M. R. (2014). Using PAT to understand, control, and rapidly scale up the production of a hydrogenation reaction and isolation of pharmaceutical intermediate. Organic Process Research & Development, 19(1), 236–243. https://doi.org/10.1021/op500285x
Mitchell, C., Strawser, J. D., Gottlieb, A., Millonig, M. H., Hicks, F. A., & Papageorgiou, C. D. (2014). Development of a Modeling-Based Strategy for the safe and effective scale-up of highly energetic hydrogenation reactions. Organic Process Research & Development, 18(12), 1828–1835. https://doi.org/10.1021/op500207r
Crump, B., Goss, C. A., Lovelace, T., Lewis, R. M., & Peterson, J. J. (2013). Influence of reaction parameters on the first principles reaction rate modeling of a platinum and vanadium catalyzed nitro reduction. Organic Process Research & Development, 17(10), 1277–1286. https://doi.org/10.1021/op400116k
Richner, G., Van Bokhoven, J. A., Neuhold, Y., Makosch, M., & Hungerbühler, K. (2011). In situ infrared monitoring of the solid/liquid catalyst interface during the three-phase hydrogenation of nitrobenzene over nanosized Au on TiO2. Physical Chemistry Chemical Physics, 13(27), 12463. https://doi.org/10.1039/c1cp20238c
Littler, B. J., Looker, A. R., & Blythe, T. A. (2010). Optimization of a Hydrogenation Process using Real-Time Mid-IR, Heat Flow and Gas Uptake Measurements. Organic Process Research & Development, 14(6), 1512–1517. https://doi.org/10.1021/op100169j
Casey, C. P., Beetner, S. E., & Johnson, J. J. (2008). Spectroscopic Determination of Hydrogenation Rates and Intermediates during Carbonyl Hydrogenation Catalyzed by Shvo’s Hydroxycyclopentadienyl Diruthenium Hydride Agrees with Kinetic Modeling Based on Independently Measured Rates of Elementary Reactions. Journal of the American Chemical Society, 130(7), 2285–2295. https://doi.org/10.1021/ja077525c
Blackmond, D. G., Ropic, M., & Štefinović, M. (2006). Kinetic Studies of the Asymmetric Transfer Hydrogenation of Imines with Formic Acid Catalyzed by Rh−Diamine Catalysts. Organic Process Research & Development, 10(3), 457–463. https://doi.org/10.1021/op060033k

Hydrogenation FAQs

What is a hydrogenation reaction with an example?

In a chemical process called hydrogenation, hydrogen is added to a molecule. At normal temperatures, hydrogenation is not thermodynamically advantageous, thus a catalyst is required. This catalyst is often made of metal. Margarine, mineral turpentine, and aniline are a few examples of goods that have been hydrogenated.

What type of reaction is hydrogenation?

A hydrogenation process, also known as a reduction reaction, occurs when hydrogen molecules are added to an alkene. Alkanes are created via an addition reaction between alkenes and hydrogen gas in the presence of a catalyst, usually metal.

What is the main purpose of hydrogenation?

Hydrogenation is a process widely used in the chemical industry to add hydrogen to unsaturated organic compounds, with the aim of producing saturated compounds. Chemical engineers are heavily involved in the design and optimization of hydrogenation processes, which play a vital role in various industries, including food and fuel production.

In the food industry, hydrogenation is commonly used to produce solid fats from liquid oils, such as margarine and shortening. By hydrogenating vegetable oils, their stability, functional properties, and overall quality can be improved. Similarly, in fuel production, the hydrogenation of unsaturated hydrocarbons in crude oil can produce more stable and less reactive compounds.

As a crucial part of the hydrogenation process, chemical engineers must select appropriate catalysts, design reactors, and process conditions to optimize conversion and selectivity, and manage safety considerations associated with high-pressure hydrogenation reactions. Additionally, they must strive to develop sustainable and environmentally friendly hydrogenation processes that minimize waste and energy consumption.

What are the reaction conditions for hydrogenation?

The typical reaction conditions for hydrogenation depend on the specific reaction and the reactants involved. Some common parameters that are often used in hydrogenation reactions include:

Temperature
Pressure
Catalyst
Solvent
Hydrogen source
Reaction time

The reaction conditions used for hydrogenation reactions depend on the specific reactants and the desired product, and optimization of these conditions can lead to improved reaction efficiency and selectivity.

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Hydrogenation Reactions

Safe Reaction Monitoring at Elevated Temperature and Pressure

Hydrogenation of Nitrobenzene

Types of Hydrogenation Reactions

1. Reduction Hydrogenation

This type of hydrogenation involves the reduction of a compound with hydrogen. For example, an alkene can be reduced to an alkane by adding hydrogen atoms to the double bond.

2. Hydrogenolysis

This type of hydrogenation involves the cleavage of a chemical bond in a molecule using hydrogen. For example, an ester can be hydrolyzed to an alcohol and a carboxylic acid by adding hydrogen atoms across the C—O bond.

Mechanism of Hydrogenation Reaction

Industry Examples and Commercial Applications of Hydrogenation

Fine Chemicals: Tracking Exothermic Hydrogenation Steps With RC1

Fine Chemicals: Efficient Hydrogenation Catalyst Screening Using In-Situ FTIR

Pharmaceutical: Asymmetric Transfer Hydrogenation

Challenges of Hydrogenation Reactions

Environmental Impact of Hydrogenation

Hydrogenation Catalyst Screening

Catalyst Selection

Catalyst Deactivation

Safety Measures for Conducting Hydrogenation Reactions

Additional Resources

Related Products

ReactIR

Reaction Calorimeters

Scale‑up Suite

EasySampler

Chemical Synthesis Reactors

Pressure Reactors

Citations and References

Hydrogenation FAQs

What is a hydrogenation reaction with an example?

What type of reaction is hydrogenation?

What is the main purpose of hydrogenation?

What are the reaction conditions for hydrogenation?

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