Questions tagged [grignard-reagent]

For questions about Grignard reagents RMgX (R = alkyl/aryl/vinyl, X = halide): their chemical and physical properties and reactions.

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Reaction of Grignard reagents with phosphoric acid derivatives

The use of Grignard reagents that people are most familiar with is the production of tertiary alcohols by reaction with a suitable carbonyl compound, whether it be an ester, ketone, or aldehyde. As I ...
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Mesylation of cyanohydrins [closed]

Is it possible to add methane sulfonyl chloride to benzaldehyde cyanohydrin, or add toluene sulfonyl chloride to form the tosylate group on the alcohol and then perfom a grignard reaction on the ...
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Grignard-type reaction of 3-bromocyclohexene, or rather recombination?

I have a question regarding a proposed Grignard-type reaction which involves the conversion of 3-bromocyclohexene to 1-(cyclohex-2-en-1-yl)propan-1-ol, in diethylether. As the bromine atom lies in ...
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166 views

Bond type in Grignard reagent

I just want to confirm if the $\ce{R-Mg}$ bond is a covalent bond which undergoes heterolytic fission during reactions while the bond between magnesium and halogen atom is ionic. Am I right or wrong?
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Can Mg/ether reduce carbonyl groups?

One of the ways of preparing Grignard reagent is: $\ce{R-X ->[Mg/ether] R-MgX}$ However let's assume that a carbonyl group is present along with a halide in the substrate. Will $\ce{Mg/ether}$ ...
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41 views

Which double bond will PhMgBr attack and why? [duplicate]

I am confused about which double bond will undergo nucleophilic addition.C=O should undergo but the book says the double bond of the ring.Please tell why
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Grignard Reagent Facilitates Epoxide Opening

I have read from my textbook, that the opening of an epoxide ring with a strong nucleophile like a Grignard reagent, takes place from a less substituted side, with a higher SN2 character. The acidic ...
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Can a Grignard reagent form magnesium halide with an alkyl halide? [duplicate]

$$\ce{RMgX + R'X' -> RR' + MgXX'}$$ Is this reaction possible? I am not able find any reference to it in the books that I have. Anyone has a reference?
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How many equivalents of Grignard reagent does a nitrile group consume?

I was looking at reactions of grignard reagent with certain kinds of compounds and came across it's reaction with nitrile group: What I was wondering is what if we don't react the Imine formed after (...
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59 views

Preparation of Alcohols from Grignard Reagent

We were given this question in the class: Answer given: I got 2-Methyl Butanol. Why doesn't the methyl attack the 2nd carbon atom from the oxygen atom and form 2-Methyl Butanol instead of attacking ...
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Reacting Grignard reagent with esters to excusively produce a ketone [duplicate]

Adding 2 moles of grignard reagent to an ester, gives out 2 alcohols. But, if 1 mole of grignard reagent is added, will the reaction exclusively produce a ketone? How to prepare a ketone in a reaction ...
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Stereochemistry & mechanism of β-cyano enone methylation

I am helping a friend with some upper-level mechanism problems. We came across this one. This is my proposal. Do you agree/disagree? Thank you for any input. Source question:
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146 views

Reacting Grignard reagent with amides

Propene in the presence of $\ce{HBr}$ and $\ce{H2O2}$ gives A. A on reaction with $\ce{Mg}$ in dry ether gives B. B on reaction with acetamide, $\ce{CH3C(O)NH2}$, gives C. In the above question, I ...
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156 views

Reaction of acyl chloride with excess Grignard reagent

I have a reaction to which I must find the majority organic product. I think I found the correct product but the fact that the reaction takes two moles of propylmagnesiumbromide confuses me a bit. I ...
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283 views

Synthesis of (1S,2S,4S)-4-ethenyl-5-methylcyclohexane-1,2-diol

I'm trying to devise a synthesis for the following question. I am aware it involves retrosynthetic, Wittig, Grignard and diels alder reactions, but unfortunately I can't really grasp all concepts ...
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115 views

Grignard reaction with cycloheptatriene

I'm having trouble with the following set of reactions and their products. Product A is achieved by exploiting the unique aromaticity of cycloheptatriene cations. When A is treated with the Grignard ...
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Why are Grignard reagents nucleophiles and not ambiphiles?

The way I see it, the -R (alkyl part) obtains a negative charge and the MgX obtains a net positive charge on bond dissociation. So a nucleophile and an electrophile both are obtained simultaneously. ...
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Will a crystal of iodine lower the yield of an Grignard Reaction

I discussed the following today: If adding an iodine crystal to a Grignard to make the reaction go. will this tiny crystal force some of the metal or reagent to be used up. ergo, therefore, there is ...
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How do I synthesise this tertiary amide from these 5 compounds?

So basically I'm at a loss as to how to proceed. I started with the idea of converting the primary alcohol into an aldehyde and that is where I stoped. I understand that each substituent of the ...
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Why can't Grignard reagents react like Organolithium does (with acids)?

I'd read yesterday that Grignard reagents can't give ketones on reaction with carboxylic acids. It is because of the fact that Grignard reagent is a "super-base", and it will deprotonate the ...
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166 views

Ways to determine the concentration of alkyl halides in organic solvents

I have a volatile alkenyl bromide dissolved in hexanes. I have to use the halide in a Grignard reaction but separating it from hexanes is hard (the bromide is light sensitive and very volatile). I ...
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106 views

Why does magnesium bromide transfers from a carbon atom to nitrogen in piperidine?

In this reaction, why does $\ce{MgBr}$ goes to the $\ce{>NH}$ group and form a bond with nitrogen by removing $\ce{-H}$. Also where does the negative charge go?
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Reaction Of Grignard's Reagent with Acyl Chloride

My organic chemistry book says that Grignard reagents react with acyl chloride just as hydride reagents. Further in an in-text question now using above theory, my answer is But Answer in Solution ...
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797 views

Why do Grignard reagents act as sources of nucleophilic R− and not Br−?

In reactions with Grignard reagents, I've always seen the alkyl group being the nucleophilic component, with the R–MgBr bond being broken. This is always rationalised by the fact that the alkyl carbon ...
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Grignard with nitrile: why is the imine protonated twice?

Steps 2 and 3 in the picture show the imine being protonated twice to form the iminium ion in step 4. I'm a little confused as to why the second protonation occurs; does the imine after step 2 still ...
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477 views

Priority order of attack of grignard reagents on functional groups

Recently I was solving carbonyl compounds and I came across this. Is there some priority order, or logic behind why alcohol reacts first with Grignard reagent and then ketone. Whereas ester could've ...
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126 views

Hydride shift and Ring Expansion

Below is a problem I got stuck at in a test . The first compund in this chain was easy to figure out , it was something like this : Then I had this intermediate compound for B.(I didn't add the ...
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Preparation of Grignard reagent. Free radical rearrangement

Mechanism of formation of Grignard Reagent $$\ce{R-X + ^.Mg^. ->[\text{r.d.s.}] R^. + ^.Mg+X-} $$ $$\ce{R^. + ^.Mg+X- -> R-Mg+X-} $$ As the mechanism of preparation of Grignard reagent suggests,...
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Why ester reaction with one equivalent of Grignard reagent produces ketone?

While reviewing my old materials before an external exam which also covers these topic I stopped by one of the reactions - Grignard w/esters: From what I remember, and what my notes are also telling ...
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Is it possible to produce an epoxide from 2-bromoacetyl bromide using methyl magnesium bromide

This is also one of the questions from practice papers for the JEE , asks for 2 step reaction for epoxidation of ketene For product A , π complex is generated on c-c bond since carbon labelled 1 is ...
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Grignard reagent will act as a base or a nucleophile [duplicate]

R- from grignard reagent (RMgBr) and gilmann's reagent (R2CuLi) although being a strong base reduces the carbonyl group and does not act as a base. Why can't it abstract the alpha hydrogen forming an ...
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Grignard alkoxide intermediate as starting material for ether or ester synthesis

I'm having a Grignard reaction between a ketone or aldehyde with RMgX in mind. The average workup uses water to hydrolize the intermediate alkoxide. But could this intermediate be used without ...
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259 views

Will a Grignard reagent react with an epoxide or episulfide first? [closed]

In this question, I am confused whether the Grignard reagent will attack the epoxide or the episulfide (thiirane) first. The solution says ring opening of the episulfide will occur due to greater ...
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Chirality and number of sterioisomers

I have recently read that the number of sterioisomers in a compound having n chiral centres is $2^n$. (That is, if no meso form is present) The below question asks for the number of sterioisomers in ...
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Addition of Methyl Grignard and use of HClO4 in this question

Okay so the first step is the use of Grignard. I know that Grignard does a 1,2 addition(generally) and the attack happens directly on the carbonyl,and I think HClO4 basically does protonation.Not sure ...
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Reaction of grignard in presence of Halogen [closed]

What happens when a Ketone say $$RCOCH3$$ on reaction with grignard reagant in presence of X2 (halogen) what happens?? Can someone please explain
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Confirmation regarding nucleophilic addition of Grignard reagent

$\ce{A ->[(i)EtMgCl][(ii)H2O] Et3C-OH}$ A can be: a) $\ce{COCl2}$ b) $\ce{EtCOOEt}$ c) $\ce{Et2CO}$ d) $\ce{All}$ The answer should be (d) according to me, but is marked as (a) in the answer key. ...
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Allylic Rearrangement in formation of Grignard Reagent

Is an allylic rearrangement possible in formation of Grignard reagent? Going by the following single electron transfer mechanism, I think it's possible. But, I haven't found any references.
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Why is this grignard synthesis incorrect?

This reaction is mentioned as incorrect in my exercise book. Why is this so? My guess was that the Magnesium, instead of forming a grignard reagent with the compound and bromine, would instead form a ...
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A compound that reacts with ethyl magnesium bromide and also decolorizes bromine water

Which of the following compounds reacts with ethyl magnesium bromide and also decolorizes bromine water solution: Is the answer only option (c)?
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Grignard reagent with sulfur dioxide

I have studied that the Grignard reagent $\ce{RMgX}$ reacts with $\ce{CO2}$ to form $\ce{RCOOH}$ after acid hydrolysis. But does the same apply for sulfur dioxide? Grignard reagents are good bases ...
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Preparation of 3-ethylpentan-3-ol

Is it possible to use CI3TMS (a carbon with three iodo groups and a trimethylsilyl protecting group) and three equivalents of an ethyl grignard reagent to prepare 3-ethylpentan-3-ol? By deprotecting ...
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Reaction rate of Mg with aryl halides

I have been thinking of the rate of reaction of aryl bromide and aryl chloride with $\ce{Mg}$ to form Grignard. When considering the electronegativities the carbon in aryl chloride is more ...
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Grignard alkene on a carbonyl

I was given the following mechanism to prove today post-lecture: and my attempt is given below. Now, when the negative charge on the alkene attacks the carbonyl, the electrons are pushed onto the ...
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Reactivity of Grignard reagent

I had the following question at an exam: What is the fastest reacting compound towards nucleophilic addition with Grignard reagent? (a) Acyl chloride (b) Aldehyde (c) Ester It is obvious that ester ...
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245 views

Reaction of 1 equivalent of Mg in ether with 1,4-dibromobut-2-yne

What will be the product formed the if the reaction of Mg in ether with 1,4-dibromobut-2-yne occurs? At first, I thought the answer would be cyclobutyne, but the correct answer is buta-1,2,3-triene. ...
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What is wrong in this reaction? [closed]

What is wrong in this reaction? I cannot find anything wrong, please help. Any hints would be appreciated.
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What will form when Dihalides or Trihalides or Polyhalides react with Magnesium?

I know that "R-X + Mg" gives RMgX. I want to ask if the Halide is Poly, then How's the formation of Grignard take place? For example. If 1,4 - Dibromobutane react with Mg, then what will be the ...
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675 views

Grignard reagent and acidic hydrogen

Why does the Grignard reagent not react as a base in case of ketones even though the α-hydrogen atom in case of ketones is acidic? Grignard reagents do react with ethyne to give hydrocarbons, so why ...
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353 views

Carbonation of Grignard reagent with a carbonyl group present in it

Here's the question in my book (see picture) Option A is a standard reaction which gives a carboxylic acid. Option B is definitely wrong because an acid base reaction will take place and CH4 will be ...