Questions tagged [catalysis]

This tag is appropriate for reactions, their mechanisms, their kinetics, when catalysts of any kind are involved.

92 questions with no upvoted or accepted answers
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307 views

What might serve as an initial starting photocatalyst for this large water-splitting solar simulator?

Question: What might serve as an initial starting photocatalyst for this large water-splitting solar simulator? Surely there must have been some planned experiments! The Gizmodo article Insane Light ...
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92 views

Why do poisoned catalysts (Lindlar, nickel borate) result in partial hydrogenation of alkynes?

I read that alkene is more reactive than alkyne, so in hydrogenation of alkynes, it's difficult to isolate the alkenes. But with poisoned catalysts like Lindlar's catalyst or Nickel-Boron (Ni2B), they ...
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356 views

Why do catalysts have limited turnover numbers in practice?

I quote the Wikipedia page definition for Turnover number: In other chemical fields, such as organometallic catalysis, turnover number (abbreviated TON) has a different meaning: the number of moles ...
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139 views

What is the mechanism of benzyl ether hydrogenolysis?

The mechanism for the hydrogenation of alkenes or alkynes using Pd/C is fairly well explained to involve the absorption of hydrogen onto a metal's surface followed by the addition of that hydrogen ...
4
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45 views

Curtin-Hammett principle to evaluate alkene insertion

Given an unsymmetrical alkene in a simple non-stereoselective catalytic hydrogenation reaction. If one would want to investigate the nuances in the catalytic cycle of a dihydride complex leading to ...
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86 views

What is it that makes this noncontact catalytic system unique in 2020?

Phys.org's Accelerating chemical reactions without direct contact with a catalyst discusses the new Science Advances paper Noncontact catalysis: Initiation of selective ethylbenzene oxidation by Au ...
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69 views

CuAAC "Click" reaction giving inconsistent results

I apologize in advance for the large amount of text and thank all those who take the time to read it. The "Click" reaction after Fokin and Sharpless is known to achieve high yields without long ...
4
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0answers
67 views

Meaning of electrochemical vs nonelectrochemical steps

Can someone please explain to me what is meant by an electrochemical reaction step and how it differs from a nonelectrochemical reaction step in the same overall reaction in the context of ...
4
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59 views

Pd-catalysed hydrogenation of imines

Hydrogenation of imines to amines by $\ce{H2}$ on $\ce{Pd/C}$ has been used e.g. in the synthesis of Pumiliotoxin. By contrast, carbonyl groups are rarely reduced in this way, which I though was due ...
4
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0answers
2k views

How does Lindlar's catalyst work?

I can not find a mechanism online. I understand that some poisoning effect causes the catalyst to be unable to reduce an alkene to alkane; however, if the catalyst is poisoned, how does it continue to ...
3
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37 views

Why is the Tolman electronic parameter defined the way that it is?

I'm currently writing up a report on Hydrocyanation and I've been reading up on parameters people regularly use to justify their observations in regard to the performance of certain catalyst systems ...
3
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0answers
53 views

Purification of Buchwald-Hartwig amination

I am conducting a synthesis involving Buchwald-Hartwig amination. I use $\ce{Pd2(dba)3}$, $\ce{P(o-tol)3}$, and $\ce{Et3N}$ as base. In many proposed mechanisms, they often omit the precatalyst. I ...
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50 views

Advantages of p-toluenesulfonic acid over sulfuric acid in the formation of acetals

I am currently working on an undergraduate experiment to form a cyclic acetal. We were asked to use p-toluenesulfonic acid as a catalyst rather than sulfuric acid. This seems to be common practice ...
3
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37 views

database for catalytic reaction mechanism

I am looking for a database containing detailed reaction mechanisms for (homogenous) catalytic reactions. Regular organic textbooks or papers generally draw some broad picture of how the mechanism may ...
3
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58 views

Why is NOₓ conversion low at fuel rich conditions in a three-way catalytic converter?

$$ \begin{align} &\text{Oxidation:} &\quad \ce{2 CO + O2 &-> 2 CO2}\\ & & \ce{``HC" + O2 &-> CO2 + H2O}\\ & & & \\ &\text{Reduction:} &\quad \ce{2 CO +...
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570 views

Reaction between Sodium Thiosulfate and Iron Chloride

I'm doing a paper on catalytic effectiveness in this reaction, and am trying to identify how the catalysts are speeding up the reaction. Based on what I can find, $\ce{Fe}$ starts as $\ce{Fe^3+}$, ...
3
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180 views

Role of Lewis acid in synthesis of adamantane from bicyclic species

What is the role of $\ce{AlCl3}$ in the following synthesis of adamantane? I'm guessing it functions as a Lewis acid, but I am unsure how the mechanism of the second step works, as there is no region ...
3
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100 views

What are some reactions which can be used to study "Effect of Catalyst on the Rate of Reaction"?

I wish to study the effect of catalyst on the rate of reaction as an investigatory project. What are some reactions and ideas that I could use to study this? One example to this is the decomposition ...
3
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0answers
286 views

Is there a catalyst for the decomposition for hydrogen peroxide that speeds it up but still makes the reaction light dependent?

I am building a Rube Goldberg machine for Science Olympiad, and one of the scoring steps is to use light to trigger a chemical reaction, which made me immediately think of the decomposition of ...
3
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112 views

Selectivity of olefin cross-metathesis reaction

I'm looking at the reaction shown below which uses a ruthenium catalyst: I am confused because the ruthenium catalyst which is used in the reaction should be Z selective due to the features on the ...
3
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331 views

Reaction with Urushibara Catalyst

I'm not a chemist, nor an organic chemistry student, but I do a lot of research. I have a question about the end of this synthesis. Dissolve 5g pure phenylnitropropene in 50ml Ethanol and add to Ni ...
3
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139 views

How does metal ions assist oxidative rancidity?

Oxidative rancidity is defined as the oxidation of unsaturated lipids and the carbon-carbon double bond with the presence of typically oxygen gas. Sometimes aldehydes and ketones are released as ...
3
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44 views

Does product induced poisoning qualify as a rate limiting step?

I have a question about whether a particular situation qualifies as a rate limiting step. I have a catalyst that under normal conditions gets poisoned when products accumulate on the catalyst surface. ...
3
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1k views

What are the specific disadvantages of using a bio-catalyst (called Lipolase) in the synthesis of the drug pregabalin?

I am studying the synthesis of a drug pregabalin, for which both chemical and bio-catalysts are used. Using a biocatalyst is way better than chemical route, as explained here. In fact, The invention ...
3
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118 views

Photoelectrochemical (PEC) water splitting

I'm starting to prepare for my research project on photoelectrochemical (PEC) splitting of water into H and O using (F doped) titanium dioxide as the photoanode. I've been unsuccessfully searching in ...
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29 views

Can an alloy catalyst change during a reaction?

I am studying the reaction pathway of oxygen evolution reaction (OER) on a PtNi alloy catalyst using density functional theory (DFT). What I found is that, for different intermediates, the most stable ...
2
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38 views

What is the rate constant k for the reaction between potassium manganate and oxalic acid?

For my school's chemistry classes, I am investigating the kinetics of the redox reaction between $\ce{K2MnO4}$ and $\ce{C2H2O4}$. I analyzed the data using a colorimeter set to $\pu{565nm}$. ...
2
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82 views

Hydrogen peroxide and potassium iodide reactions

What is the explanation for the two possible reactions of $\ce{H2O2}$ with $\ce{KI}$ in acid media (iodide-catalyzed decomposition of hydrogen peroxide or iodide oxidation by hydrogen peroxide) and ...
2
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0answers
18 views

Why do electrocatalysts based on polyoxometalates and carbon materials have a weaker activity/performance in acidic media?

I am testing now some doped N and S doped carbon nanomaterials alone and immobilized in POM for the purpose of developing a nanocomposite that can serve as an electrocatalyst for energy-related ...
2
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0answers
90 views

Reactivity of Ni Vs. Pd - available oxidation states

I'm hoping someone can help me tighten up my understanding of the origins of the differences between Ni and Pd catalysis. I understand that Ni has higher charge density and this is the reason for it'...
2
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0answers
40 views

What is the mechanism of platinum as catalyst poisons on alumina?

I'm wondering if anyone knows by what mechanism is platinum (or other noble metals) catalyst on alumina substrate poisoned? Presently, I'm using platinum on alumina to decompose a hydrogen peroxide / ...
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155 views

What happens to promoters or poisons during a catalyzed reaction?

Catalysts are substances that influence reaction rates without undergoing changes in their mass and chemical composition, but may undergo physical changes. Promoters, poison etc. affect the activity ...
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594 views

Rate order of decomposition of hydrogen peroxide

I have been having some troubles finding a source for my investigation. I am inverstigating the decomposition of hydrogen peroxide, which (according to my teacher/supervisor) is a second order ...
2
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0answers
81 views

Name for reaction producing carbon from CO2

Some years ago I heard of a reaction where hydrogen could be used to reduce $\ce{CO2}$ to carbon and water, similar to the Sabatier reaction. I believe it also used iron as a catalyst at high ...
2
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0answers
450 views

Units on rate constants from transition state theory and DFT

I am using density functional theory (DFT) to compute the energy profile and, by extension, kinetic parameters for a catalytic process. I know that the rate constant from transition state theory (TST) ...
2
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0answers
53 views

Calculate optimal surroundings for given reaction mechanism to lower activation energy?

Let's take a reaction that's fairly well understood, which in this case means that the reaction mechanism is known, maybe something like this from here: If we know the reaction mechanism, we also ...
2
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0answers
1k views

How to reduce Al2O3 in a H2 atmosphere on industrial scale?

As known, reducing $\ce{Al2O3}$, which is the main process of the aluminium production, isn't really cheap, mainly because its energy need. Its high energy need is coming from the high binding energy ...
2
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0answers
114 views

Selectivity of catalysts

What is the reason behind the fact that methane on controlled oxidation gives methanol in presence of Cu catalysts whereas formaldehyde is obtained if we use molybdenum oxide ($\ce{Mo2O3}$)? IUPAC ...
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0answers
51 views

Can fluid catalytic cracking work on a smaller scale in a laboratory?

Fluid Catalytic Cracking usually requires a very large and tall structure. Is there a way of miniaturizing the process to fit inside a chemical lab with 10 ft ceilings? Specifically: can a fluidized ...
2
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0answers
34 views

Are there any suitable catalysts for ferric oxide and aluminum reaction?

As an exercise, I am trying to figure out how to catalyze the reaction of ferric oxide and aluminum Fe2O3 + 2Al -> 2Fe + Al2O3 I've been trying to find a substance A such that the reaction could be ...
2
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1answer
693 views

Catalytic poison in Pt catalysed manufacture of H2SO4

I came across a question that goes as: In manufacturing of sulfuric acid in presence of platinum catalyst, which metal impurity acts as a catalytic poison? Fe Cr Cu V I searched ...
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52 views

What is the product of reaction between 2‐cyclobutyl‐2‐isopropyl‐1,3‐dioxane and hydrogen with Raney nickel?

I have 2‐cyclobutyl‐2‐isopropyl‐1,3‐dioxane (alcohol protection) and I have to react it with $\ce{H2}$ and Raney nickel, but I don't know what the product would be. I have seen a similar reaction ...
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0answers
30 views

catalysts in catalytic hydrogenation

I am studying the very BASIC introduction of catalysis in general chemistry and encountered an example of a heterogeneous catalyst, which is catalytic hydrogenation of alkene into alkane using Pt/C or ...
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48 views

Why is copper(II) used a catalyst here instead of as an intermediate?

Photochromic glass, used for sunglasses darkens when exposed to bright light and becomes more transparent again when the light is less bright. The depth of color of the glass is related to the ...
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0answers
36 views

Are there any chemical pathways or catalysts that could produce electricity from fossil fuels without combustion?

While fossil fuels are dense in energy, I have known only one way to retrieve energy from them, namely, to burn them. I wish we could have a way to get energy from them without combustion. Is there ...
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0answers
72 views

Is activation energy directly related to the reaction rate? (keeping the temperature, concentration, catalyst, particle size and pressure constant)

For different chemical reactions, does the activation energy of that reaction directly relate to the reaction rate? In other words, would a reaction always be slower if it had a higher activation ...
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0answers
38 views

Will a Lewis acid catalyze the reaction of HBr with primary alcohols?

It is well-established that a Lewis acid catalyst (popularly $\ce{ZnCl2})$ is necessary to form an alkyl chloride when reacting $\ce{HCl}$ with a primary alcohol. This actually changes the mechanism: ...
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0answers
26 views

What is the equation that describes the variation in concentration of an inhibitor in an heterogeneous catalysis?

I find myself in quite a pinch: I have to sustain a Chemical Physics exam, and I know for a fact that the professor often asks this particular question: Suppose that we have both a reacting species ...
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0answers
32 views

Why isn't the base reformed in base-catalyzed hydrolysis of esters?

In acid-catalyzed hydrolysis, the hydronium ion is clearly reformed; however, in the base-catalyzed hydrolysis, an alcohol is formed as a by-product, but the strong base isn't reformed. Is it a ...
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0answers
24 views

Why do polyoxometalates have good electrochemical/ redox properties?

Many authors are using polyoxomethalates immobilised in carbon nanomaterial as electrocatalysts for energy related reactions (ORR, HER, OER). Other metal alloys have also shown to be successful as ...