Questions tagged [reaction-control]

Questions related to the chemical and physical influences that influence the rate and probability of chemical reactions. Not to be confused with [catalysis] or [reaction-mechanism].

32 questions with no upvoted or accepted answers
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9
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229 views

Aza-enolates: why no reaction at N

My understanding is that aza-enolates have an advantage over enamines in enolate-type alkylations because the reaction at N is less likely. As a result, unactivated electrophiles can be used (i.e. ...
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97 views

How well will molten iron chrysolite (fayalite) react with hydrogen?

The equation balances nicely, but would the reaction tend to proceed this way? What temperature and time would be needed? $\ce{Fe2SiO4 + 2H2 -> 2H2O + 2Fe + SiO2}$ There is no problem with ...
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635 views

Role of pH in azo C-coupling reaction, continued

In the question, "What is the role of pH in azo coupling reaction of diazonium with phenol and aniline?" asked by @DhrubaBanerjee and answered by @Klaus-DieterWarzecha, I find several ends ...
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Increasing C-alkoxycarbonylation of enolates

I am working with N-tosyl-2-piperidone and attempts to use the lithium enolate of this compound to perform an nucleophilic acyl substitution reaction on an several chloroformate esters in THF has lead ...
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107 views

Is there a way to force C-protonation of an enolate?

In another question, I mentioned that O-protonation of an enolate followed by tautomerization may lead to increased amounts of the thermodynamic product over the kinetic product (when those are ...
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35 views

Decarboxylation of THCA during CO2 Extraction of Cannabis

We have a strange problem. We are performing CO2 extraction on cannabis and we are seeing considerable decarboxylation of THCA to THC. We have high quality temperature sensors at the heat exchangers, ...
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52 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 ...
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81 views

Clash between thermodynamic and kinetic processes

I have often come across reactions where kinetic and thermodynamic processes give completely different outputs. I was told that in such cases check temperature, if temperature controlled, then take ...
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84 views

Grignard reaction - exchange of groups

Why is this reaction successful: Why doesn't metal-halide exchange occur easily to get Ar-MgCl and R-Br?
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54 views

Other than heating, is there any evidence that normal RF radiation (say, microwave range) can affect chemical reactions?

There's been a lot written (and debunked) about alleged biological effects from RF radiation, even when it's too low powered to cause heating effects or ionization. Is there any chemical reason to ...
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32 views

Enantiomers in anisotropic achiral chemical environments

Consider a functionalised molecular box or cage which has an electrostatic gradient due to positively charged groups one one of its faces. This environment is achiral as there are reflection ...
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182 views

Can activated charcoal retain adsorbtion properties even when submerged in liquids?

This is following a question on Skeptics Stackexchange, where apparently medical science claims that activated charcoal can adsorb poison when ingested. One of the members posted a related question on ...
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64 views

Is there wavefunction interference between alternate reaction pathways?

I'll give a specific example to clarify my question. If we look at the approach of chloromethylenecarbene's electron pair to cis-2-butene in the reaction of creating 1-chloro-2,3-dimethylcyclopropane, ...
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36 views

How do I find the rate constant in this situation?

Say I have two kinds of molecules $A$ and $B$. The molecules of type $B$ are small and bind onto molecules of type $A$. (Any number of them may do so, but in practice this number is $\leq 8$.) We ...
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40 views

Can there be gaps in autoignition temperatures?

I recently saw a request for solids that auto-ignite between 80C and 160C. I can't find any, and none have yet been suggested. Which leads me to the theoretical question: Is it possible for there to ...
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79 views

Controlling rate of endothermic reaction

In an experiment, I have two endothermic reactions taking place simultaneously: $$ \begin{align} \ce{A + B &-> C + D}\tag{1}\\ \ce{E + G &-> Z + F}\tag{2} \end{align} $$ $\ce{C}$ and $\...
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66 views

How to predict and measure excess values of reactivity ratios for copolymerization with three monomers?

I ask this question because I haven't found interesting literature on the subject and I would like to know if my way to think is good or pure bullshit. Also the question is quite long because I have ...
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67 views

Is chemical equilibrium possible at any temperature and pressure?

Consider the chemical reaction ${\rm Na+Cl\to NaCl}$ by mixing ${\rm Na}$ with ${\rm Cl}$ (or by mixing ${\rm NaOH}$ with some acid). This process is exothermic while the reverse ${\rm NaCl\to Na+Cl}$ ...
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184 views

Aluminium etching

I'm trying to etch a very fine pitch ($\pu{0.5 mm}$) aluminium stencil for use with SMT printed circuit board making. I've done some reading on the topic and found that the safest way probably is to ...
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154 views

Could stabilized aqueous ozone be bottled to prevent half life/sanitization window?

Could stabilized aqueous ozone be bottled to prevent half life/sanitization window? Typically upon creating stabilized aqueous ozone, it has a shelf life and a sanitization window of 24 hours from ...
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183 views

Will Ethanol degrade Silicone or “RTV” specifically “RTV 734”, or cause it to “leach” ingredients at temperatures below 250 degrees farenheit?

Will Ethanol degrade Silicone or "RTV" specifically RTV 734, a flowable sealant produced by Dow Corning, or cause it to "leach" ingredients at temperatures below 250 degrees Fahrenheit? Such as in ...
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70 views

Mathematical model for reaction rate in fixed volume

Is there a way to find the rate of reaction of a chemical reaction inside a closed container that is fixed in volume as a function of time? Can the answer provide an example reaction (such as baking ...
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410 views

Water-gas shift reaction without catalysts

I'm designing an experimental gas generator. The details are not really important here, but I want to convert a mixture of carbon monoxide, hydrogen and $\ce{H2O}$ gas to a safer form. I know the ...
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34 views

Return time after perturbation in a chemostat

I'm wondering how I can derive the return time of the culture cell concentration back to a steady-state in a chemostat after a small perturbation of the bulk culture cell concentration. More specific,...
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199 views

Chemical equilibrium and Le Chatelier Braun for ammonia production

In the book of Chemical, biochemical and engineering thermodynamics 4th edition from Stanley I. Sandler (Wiley, 2006), there is a problem about the ammonia producing reaction at page 770. 13.17 The ...
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46 views

Limit the production of hydrogen in a small container

I have to produce hydrogen at a near-constant pressure inside of a really small container without using an automatic pressure release value. I would like the pressure to be relatively high, but the ...
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30 views

What does spontaneous mean in term of forward and reverse reactions?

I just learnt about Gibb's Free Energy and was thinking about an exothermic reaction with a negative change in entropy. This means that the reaction would occur at low temperatures. But that means ...
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39 views

Is the activation energy always inversely proportional to the reaction rate?

When I obtained the activation energy using the Arrhenius equation for a 10-minute glowstick (rapid, rigorous reaction), it was almost 4 times that of a 12-hour glowstick (slow, mild reaction). ...
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141 views

How long does it take Freon refrigerant to disappear from a room after an accidental major leakage?

I would like to know please how long does it take Freon refrigerant to completely disappear from a room after an accidental major leakage? Does it stick to surfaces , clothes or walls? Does natural ...
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34 views

What factors affect the chemiluminesnence of a glow stick reaction?

I know that temperature affects the reaction rate of a glowstick, but are there any other factors? I was thinking the different color dye molecules would have an effect on the reaction rate, since ...
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38 views

Chloride Process TiO2 recovery

In the chloride process (the process used to create titanium oxide from titanium ore), how is TiO2 collected? What prevents the TiO2 from building up on the walls of the reactor chamber? It's my ...
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122 views

Why mixture turns brown upon heating, during esterification with H2SO4?

In the lab I was synthesising an ester with sulphuric acid as a catalyst. However the mixture turned brown and my teacher said I had burnt the acid, but what does this actually mean?