Does Raney Nickel Reduce Carboxylic Acids?

Raney nickel is a powerful catalyst that can be used to reduce a variety of compounds. It’s particularly effective at reducing compounds with multiple bonds, like alkynes, alkenes, nitriles, dienes, aromatics, and carbonyl-containing compounds. It also works well with heteroatom-heteroatom bonds, such as hydrazines, nitro groups, and nitrosamines.

Let’s break down these types of compounds and see how Raney nickel can help.

Alkynes and Alkenes: Raney nickel readily reduces alkynes (compounds with a triple bond) to alkenes (compounds with a double bond) and then further to alkanes (compounds with only single bonds). This ability to selectively reduce these bonds makes it a valuable tool for organic synthesis.

Nitriles: Nitriles are compounds with a carbon triple-bonded to a nitrogen. Raney nickel reduces them to amines. This reaction is often used in the production of pharmaceuticals and other chemicals.

Dienes and Aromatics:Dienes are compounds with two double bonds. Raney nickel can be used to selectively reduce one or both of these double bonds. Aromatic compounds are characterized by a ring of carbons with alternating single and double bonds. Raney nickel can be used to reduce these double bonds, resulting in the formation of non-aromatic compounds.

Carbonyl-containing compounds: Carbonyl compounds have a carbon double-bonded to an oxygen atom. Raney nickel can reduce these compounds to alcohols. This is particularly useful in the production of alcohols from aldehydes and ketones.

Heteroatom-heteroatom bonds: These bonds are between two atoms that aren’t carbon. Raney nickel can break these bonds, which can be useful in the synthesis of various compounds. For example, it can be used to reduce hydrazines to amines and nitro groups to amines.

The power of Raney nickel lies in its ability to selectively reduce different types of bonds in a molecule, making it a versatile tool for organic chemists.

Let’s talk about reducing carboxylic acids. You’re probably wondering if diborane (B₂H₆) can do the trick. The answer is yes, but it’s a bit more nuanced than that.

Diborane is a powerful reducing agent, but it’s not the first choice for carboxylic acids. Typically, you’d use lithium aluminum hydride (LiAlH₄) to convert carboxylic acids to alcohols.

Now, why is diborane often overlooked for this job? Well, it’s because diborane is a bit more finicky when it comes to carboxylic acids. It can react with them, but it’s not as efficient or reliable as lithium aluminum hydride. Lithium aluminum hydride is a stronger reducing agent and can handle the task with more ease.

Think of it like this: diborane is like a gentle nudge, while lithium aluminum hydride is like a full-on push. Both can get the job done, but one is clearly more forceful and effective.

Let’s dive a bit deeper into why lithium aluminum hydride is the go-to for carboxylic acid reductions. It’s because lithium aluminum hydride is a complex metal hydride that can readily donate hydride ions (H^–). These hydride ions are the key players in the reduction process, attacking the carbonyl group of the carboxylic acid and ultimately replacing it with a hydroxyl group, forming an alcohol.

Diborane, on the other hand, is a weaker reducing agent. While it can react with carboxylic acids, it often leads to side reactions and less predictable outcomes. It’s less efficient at donating hydride ions, making it a less reliable choice for this specific transformation.

So, in a nutshell, diborane can be used to reduce carboxylic acids to alcohols, but lithium aluminum hydride is the preferred choice due to its greater effectiveness and reliability. It’s a more powerful and efficient reducing agent, making it the go-to option for achieving the desired transformation.

You’re right! Carboxylic acids can be reduced by catalytic hydrogenation, but it takes some special conditions.

High temperature and pressure are key. Think of it like this: you need to give the reaction a good push to get it going. The hydrogen gas needs to be able to break the strong bond in the carboxylic acid molecule, and that requires some extra energy.

Catalysts are also essential. They’re like the cheerleaders of the chemical world, encouraging the reaction to happen faster and more efficiently. Common catalysts used in catalytic hydrogenation of carboxylic acids include palladium, platinum, and nickel.

Let’s dive deeper into how this process works:

Understanding the Chemistry:

The reduction of a carboxylic acid to an alcohol involves the addition of two hydrogen atoms. This reaction is often referred to as “hydrogenolysis”, where the carbon-oxygen bond in the carboxylic acid group is broken.

Here’s a breakdown of what happens:

1. Activation: The catalyst, typically a metal like palladium, platinum, or nickel, helps activate the hydrogen gas. This means the hydrogen molecule breaks into two hydrogen atoms, which are highly reactive.
2. Adsorption: The carboxylic acid molecule and the hydrogen atoms attach to the surface of the catalyst.
3. Reaction: The hydrogen atoms react with the carboxylic acid molecule, breaking the carbon-oxygen bond and forming an alcohol.
4. Desorption: The newly formed alcohol and the catalyst detach from each other, allowing the catalyst to repeat the process.

Practical Applications:

This reaction is important for a lot of different things in the chemistry world. It’s used in the production of various alcohols, which are essential building blocks for many products, such as pharmaceuticals, plastics, and cosmetics.

For example, the catalytic hydrogenation of benzoic acid produces benzyl alcohol, a key ingredient in many perfumes.

It’s also worth noting that this reaction can be quite selective. For example, if you have a molecule with multiple functional groups, you can carefully choose the catalyst and reaction conditions to target just the carboxylic acid group. This allows chemists to control which parts of a molecule are modified, which is crucial for synthesizing specific compounds.

You’re asking about reducing carboxylic acids with hydrogen and Raney nickel, right? Let’s break down what’s happening here.

Hydrogen with Raney nickel is a powerful reducing agent. It can tackle a lot of unsaturated compounds, like alkenes and alkynes. However, it generally doesn’t touch carboxylic acids. That’s where sodium borohydride comes in. Sodium borohydride is a more selective reducing agent, often used in the presence of methanol. It targets carbonyls like aldehydes and ketones, but leaves esters, amides, and carboxylic acids alone.

So, can you reduce carboxylic acids with hydrogen and Raney nickel? The short answer is no.

Here’s why:

Carboxylic acids are pretty stable. They have a strong carbon-oxygen double bond (C=O) and an oxygen atom bonded to a hydrogen atom (O-H). This structure makes it harder to break the bonds and add hydrogen atoms to the molecule.

Think of it like this: A carboxylic acid is a bit like a stubborn castle. Hydrogen and Raney nickel are like a friendly but not very strong army. They can conquer easy targets, like alkenes and alkynes, but they can’t break through the walls of a fortified carboxylic acid.

To conquer this stubborn fortress, you need stronger weapons, like lithium aluminum hydride (LiAlH4). This is a much more powerful reducing agent than hydrogen and Raney nickel, and it can successfully break through the carboxylic acid’s defenses to add hydrogen atoms and form an alcohol.

So, while hydrogen and Raney nickel are great for tackling unsaturated compounds, they’re not the best tools for tackling carboxylic acids. You’ll need a more powerful reducing agent like lithium aluminum hydride for that task.

Raney nickel is a powerful reducing agent in chemistry, often used to break carbon-selenium bonds. While incredibly effective, it does have a few limitations.

One key limitation is lack of chemoselectivity. This means that Raney nickel can sometimes react with other functional groups in a molecule, leading to unwanted side reactions. For example, if you’re trying to break a carbon-selenium bond in a molecule that also contains a carbon-oxygen bond, Raney nickel might react with both, making it difficult to get the desired product.

Another important consideration is that Raney nickel is pyrophoric, meaning it can ignite spontaneously in air. This requires careful handling and storage, often in a sealed container under an inert atmosphere like nitrogen.

Let’s dive a bit deeper into the lack of chemoselectivity. Imagine you have a molecule with a carbon-selenium bond and a carbon-oxygen bond. You want to break only the carbon-selenium bond, but Raney nickel might not be the best choice. It’s like trying to pick a specific apple from a basket full of different fruits – you might end up grabbing a pear instead!

To overcome this challenge, chemists often use other techniques like protecting groups. These groups can temporarily block certain functional groups on a molecule, preventing unwanted reactions.

For example, if you want to break the carbon-selenium bond without affecting the carbon-oxygen bond, you might add a protecting group to the carbon-oxygen bond before using Raney nickel. This prevents the nickel from reacting with the oxygen. Once the carbon-selenium bond is broken, you can remove the protecting group, leaving you with the desired product.

While Raney nickel is a powerful tool, its pyrophoric nature and lack of chemoselectivity require careful consideration and planning. It’s not always the best choice for every reaction. By understanding these limitations, you can make informed decisions about whether Raney nickel is the right reagent for your specific needs.

Let’s dive into why NaBH4 isn’t strong enough to reduce carboxylic acids.

The carbonyl carbon in esters, amides, and carboxylic acids is connected to an atom with a lone pair that participates in resonance with the carbonyl group’s double bond. This resonance makes the carbonyl group less electrophilic and harder to reduce. NaBH4, being a weaker reducing agent, simply doesn’t have the power to overcome this resonance stabilization and reduce these functional groups.

Think of it like this: Imagine you’re trying to push a heavy rock uphill. NaBH4 is like a small, weak person trying to push the rock. It just doesn’t have enough strength. Now, imagine a powerful bulldozer trying to move the same rock. That’s like a stronger reducing agent like LiAlH4; it has the power to overcome the resistance and get the job done.

LiAlH4, a more potent reducing agent, can tackle the tougher task of reducing carboxylic acids. It’s like the bulldozer; it has the necessary power to break through the resonance stabilization and reduce the carbonyl group.

Here’s a deeper look at why NaBH4 is less effective than LiAlH4:

Hydride Reactivity: NaBH4 has a less reactive hydride ion compared to LiAlH4. This difference in reactivity stems from the electronegativity of the metal cation. Aluminum is less electronegative than boron, making the hydride ion in LiAlH4 more nucleophilic and reactive.

Steric Hindrance:NaBH4 is also less bulky than LiAlH4. This smaller size makes it less effective at attacking sterically hindered carbonyl groups. Carboxylic acids often have bulky substituents surrounding the carbonyl group, further hindering the attack of NaBH4.

Solvent Compatibility: NaBH4 is typically used in protic solvents like methanol or ethanol, whereas LiAlH4 requires anhydrous conditions. Protic solvents can deactivate NaBH4 by reacting with its hydride ions, further reducing its effectiveness.

In summary, while NaBH4 is a great tool for reducing aldehydes and ketones, it lacks the punch to overcome the resonance stabilization present in carboxylic acids. LiAlH4, on the other hand, is powerful enough to accomplish this reduction.

Sodium borohydride (NaBH4) is a powerful reducing agent, but it’s not strong enough to convert carboxylic acids or esters to alcohols. Let’s break down why this is.

Sodium borohydride is great at reducing aldehydes and ketones to alcohols, but it struggles with carboxylic acids. The reason lies in the reactivity of the carbonyl group in carboxylic acids. This group is more stable than the carbonyl group in aldehydes or ketones. In simpler terms, the carbon in the carbonyl group of carboxylic acids is less reactive than the one in aldehydes or ketones. This difference in reactivity means that sodium borohydride lacks the power to overcome the stronger bond in carboxylic acids.

Think of it this way: Imagine you have a strong lock and a weak key. The key may be able to open other, less secure locks, but it won’t be able to open the strong lock. In the same way, sodium borohydride can “open” the less secure carbonyl groups in aldehydes and ketones, but it’s not strong enough to “open” the more secure carbonyl group in carboxylic acids.

What happens when NaBH4 reacts with a carboxylic acid?

When sodium borohydride reacts with a carboxylic acid, an aldehyde is produced as an intermediate. This aldehyde is very reactive and quickly reacts further, forming back into the original carboxylic acid. This means that the aldehyde can’t be isolated.

How can you reduce carboxylic acids?

If you want to reduce carboxylic acids to alcohols, you need a stronger reducing agent like lithium aluminum hydride (LiAlH4). This powerful reagent can overcome the stability of the carbonyl group in carboxylic acids and successfully reduce them to alcohols.

Carboxylic acids are generally soluble in ethanol, toluene, and diethyl ether. This is because carboxylic acids can form hydrogen bonds with these organic solvents.

Let’s dive a little deeper into why these solvents work so well with carboxylic acids.

Ethanol is a good solvent for carboxylic acids because it can form hydrogen bonds with the carboxyl group (-COOH) of the acid. Ethanol has a hydroxyl group (-OH) that can participate in hydrogen bonding, making it a good choice for dissolving carboxylic acids.

Toluene is a good solvent for carboxylic acids because it is a nonpolar solvent. This means that it can dissolve nonpolar compounds like carboxylic acids. While toluene doesn’t form hydrogen bonds with the carboxyl group, it can still interact with the hydrophobic (water-repelling) part of the molecule.

Diethyl ether is a good solvent for carboxylic acids because it is a polar solvent. It has a dipole moment, which allows it to interact with the polar carboxyl group of the acid. This interaction is similar to how water dissolves salts – a polar solvent like water interacts with the ions of salt to pull them apart.

Think of it like this: ethanol, toluene, and diethyl ether are all like keys that unlock the “door” to dissolve the carboxylic acid. They each use different mechanisms, but they all get the job done.

Raney Nickel: A Powerful Tool for Ketone Reduction

Raney nickel is a highly porous nickel-aluminum alloy that is a fantastic catalyst for various chemical reactions. One of its most prominent uses is in the reduction of ketones to secondary alcohols.

This method is incredibly efficient when using refluxing 2-propanol containing a trace of HCl. The refluxing 2-propanol provides a suitable solvent environment, while the trace of HCl acts as a promoter, enhancing the catalytic activity of the Raney nickel.

Let’s break down the process:

Ketone Reduction: When a ketone is exposed to Raney nickel in this specific reaction environment, the nickel catalyst facilitates the transfer of hydrogen atoms from the 2-propanol to the ketone. This hydrogenation process results in the conversion of the ketone group (C=O) to a secondary alcohol group (C-OH).
2-Propanol as a Hydrogen Source: The 2-propanol acts as a hydrogen source, supplying the necessary hydrogen atoms for the reduction. The refluxing conditions ensure that the 2-propanol is constantly vaporizing and condensing, providing a continuous supply of hydrogen.
HCl as a Promoter: The addition of a trace of HCl plays a crucial role in enhancing the catalytic activity of the Raney nickel. This small amount of acid helps activate the nickel catalyst, making it more efficient in promoting the hydrogenation reaction.

In summary, the combination of Raney nickel, refluxing 2-propanol, and a trace of HCl creates a highly effective system for reducing ketones to secondary alcohols. This method is widely employed in organic synthesis due to its reliability and efficiency.

Let’s delve a bit deeper into the benefits of using Raney nickel for this specific reaction:

High Activity:Raney nickel boasts an incredibly high surface area, making it a highly active catalyst. This characteristic allows for rapid and efficient hydrogenation of ketones.
Selectivity:Raney nickel exhibits excellent selectivity for reducing ketones, meaning it preferentially targets the ketone group without significantly affecting other functional groups within the molecule.
Mild Conditions: The reaction conditions are relatively mild, requiring only refluxing 2-propanol and a trace of HCl. This makes the process suitable for a wide range of organic molecules.
Ease of Handling:Raney nickel is commercially available and relatively easy to handle, making it a convenient and practical catalyst for laboratory and industrial applications.

In conclusion, Raney nickel offers a versatile and effective solution for reducing ketones to secondary alcohols. Its high activity, selectivity, mild reaction conditions, and ease of use make it a valuable tool for organic chemists.

You’re right to ask, “Can LiAlH4 reduce carboxylic acids?”. Lithium aluminum hydride (LiAlH4) is a powerful reducing agent and is very useful for converting carboxylic acids to primary alcohols.

Let’s take a look at how LiAlH4 does this. LiAlH4 reacts with carboxylic acids to form an alkoxide intermediate. This intermediate is then protonated by water, yielding the corresponding primary alcohol. This reaction typically requires a large excess of LiAlH4 and is usually conducted in an ethereal solvent, such as diethyl ether or tetrahydrofuran (THF).

Here’s an example:

The reduction of acetic acid to ethanol by LiAlH4:

CH3COOH + 4[H] → CH3CH2OH + H2O

LiAlH4 is a very strong reducing agent and can reduce a wide variety of functional groups, including carboxylic acids, esters, and acid halides. It’s important to note that LiAlH4 is extremely reactive with water and will react violently if exposed to air. Therefore, it’s crucial to use LiAlH4 under anhydrous conditions.

LiAlH4 is a powerful reagent that can reduce carboxylic acids to their corresponding primary alcohols, opening up a world of synthetic possibilities. It’s a valuable tool for organic chemists and a testament to the power of chemical reduction.

Raney Nickel Catalyzed Hydrogenation: A Green Solution

Raney nickel is a highly porous nickel-aluminum alloy that’s a powerful catalyst for hydrogenation reactions. It’s commonly used to add hydrogen atoms to unsaturated compounds, like carboxylic acids.

This process, called Raney nickel catalyzed hydrogenation, is a green and efficient way to reduce these acids. What makes it so special?

Firstly, it’s incredibly selective. This means it can target specific bonds in a molecule without affecting others. This is a big advantage when working with complex molecules, ensuring you get the desired product.

Secondly, this method is mild. This means it can be done at relatively low temperatures and pressures, making it safer and easier to control.

Finally, it’s environmentally friendly. By using water as the solvent, it avoids the use of harmful organic solvents, reducing waste and minimizing environmental impact.

So, how does it work? Well, Raney nickel acts as a catalyst, providing a surface for the hydrogen gas to attach to. This activated hydrogen can then react with the unsaturated bonds in the carboxylic acid, transforming them into saturated compounds.

A Safe and Practical Method

The sodium borohydride-Raney nickel (W6) system is a particularly effective way to perform this reaction. Sodium borohydride is a reducing agent, providing the hydrogen needed for the reaction. The Raney nickel acts as a catalyst, speeding up the process. This combination is especially useful for reducing unsaturated carboxylic acids because it’s highly selective and can be used in water, making it a safe and practical method for various applications.

The use of sodium borohydride in this system is particularly advantageous. It’s a powerful reducing agent, capable of reducing a wide range of functional groups, including carbonyl groups and nitro groups. However, it’s also very selective, only reacting with the desired groups in most cases.

Combining this selectivity with the advantages of Raney nickel catalysis, we get a powerful tool for organic chemists. It’s a method that’s both effective and environmentally conscious, leading to a cleaner and safer approach to chemical synthesis.

We wanted to see if CO affects how well Raney® nickel works as a catalyst. To figure this out, we studied how acetophenone is changed using transfer hydrogenation. We did this both with and without CO present. The results are shown in Figures 1 and 8.

Let me break down what’s happening here. Transfer hydrogenation is a chemical reaction where hydrogen atoms are transferred from one molecule to another. In this case, the hydrogen comes from a source called a hydrogen donor, and it’s added to the acetophenone molecule. Raney® nickel acts as a catalyst, speeding up this reaction.

Now, CO is known to bind to metal surfaces, and Raney® nickel is a metal. This binding can block the active sites on the nickel surface where the hydrogenation reaction takes place. In simpler terms, CO can get in the way and prevent the nickel from doing its job effectively.

Our experiment was designed to see if this was happening. By comparing the hydrogenation results with and without CO, we could see if CO was indeed inhibiting the catalytic activity of Raney® nickel.

Figures 1 and 8 would show us the extent of the reaction (how much acetophenone was converted) under both conditions. If the reaction proceeded much slower with CO, that would confirm that CO is inhibiting the catalytic properties of Raney® nickel.

Raney nickel is a very useful catalyst with many applications in chemistry. One of its most notable uses is in the reduction of C-S bonds to C-H bonds. This is a very important reaction because it can be used to convert ketones to alkanes. This is a very useful reaction because it allows us to make alkanes from ketones.

Let’s delve deeper into this specific application of Raney nickel. The reduction of C-S bonds to C-H bonds is a two-step process. First, the ketone is converted to a thioketal. This is done by reacting the ketone with a thiol, such as ethanethiol. The second step is the reduction of the thioketal to an alkane. This is done by using Raney nickel as the catalyst and hydrogen gas as the reducing agent. This reaction is also known as the desulfurization of a thioketal.

This process has several advantages over the traditional Wolff-Kishner reaction, a common method used to convert ketones to alkanes. Firstly, the reaction conditions for the Raney nickel-catalyzed desulfurization are milder than those for the Wolff-Kishner reaction. Secondly, the Raney nickel-catalyzed desulfurization is more efficient than the Wolff-Kishner reaction. This means that the reaction proceeds faster and produces more of the desired product. Finally, the Raney nickel-catalyzed desulfurization is more selective than the Wolff-Kishner reaction. This means that the reaction is less likely to produce unwanted side products.

Overall, Raney nickel-catalyzed desulfurization is a very useful and versatile method for converting ketones to alkanes. It is a mild, efficient, and selective method that can be used in a variety of applications.

Can hydrogen on platinum reduce carboxylic acids and esters?

Can $\ce{H2/Pt}$ reduce carboxylic acids and esters? I am confused about the reducing nature of hydrogen in presence of platinum. In some books, it reduces carboxylic acid and ester while in others, not. I have checked Finar and Boyd books for it. Chemistry Stack Exchange

Reagent Friday: Raney Nickel – Master Organic Chemistry

Reduction Of Sulfur Groups (Dithianes) To Alkanes With Raney Nickel What it’s used for: Like palladium on carbon (Pd/C) and platinum on carbon (Pt/C), Raney nickel can be used for the Master Organic Chemistry

Raney® nickel-catalyzed hydrodeoxygenation and

Raney® nickel is recognized as a widely-used industrial hydrogenation catalyst for the reduction of monosaccharide sugars, nitriles, nitro- and carbonyl ScienceDirect

Myers Reduction Chem 115 – Harvard University

Borane is commonly used for the reduction of carboxylic acids in the presence of esters, lactones, amides, halides and other functional groups. In addition, borane rapidly Harvard Web Publishing

Raney Nickel–Catalyzed Hydrogenation of Unsaturated

A mild, selective, and green method for the reduction of unsaturated carboxylic acids with sodium borohydride–Raney nickel (W6) system in water is Taylor & Francis Online

21.7: Reduction of Carbonyl Compounds and Acid

Another way to reduce carbonyl groups and acid chlorides is through the catalytic addition of hydrogen. Just like the C=C bond, the C=O bond is capable of adding one mole of hydrogen. The catalyst Chemistry LibreTexts

Some like it weak: different activity of Raney® nickel in

However, the most applicable catalyst of the family is certainly Raney® nickel (metallic nickel sponge, skeletal nickel), primarily in conventional hydrogenation ScienceDirect

General synthesis of primary amines via reductive

Here a nickel catalyst—formed by pyrolysis of a nickel complex on a γ-Al2O3 support—is shown to be highly active for synthesis of primary amines via Nature

Raney Nickel Catalyzed Hydrogenation of Unsaturated

practical method for the reduction of unsaturated carboxylic acids in water. We have selected sodium borohydride as hydrogen source and Raney nickel (W6 grade) as ResearchGate