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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1,4 (conjugate) addition in unsaturated aldehydes and ketones

When carbonyl compounds react with grignards, they usually give a 1,2 addition (direct addition) product. However, under certain conditions, they give conjugate addition (1,4 addition) product as the ...
Ayanokouji Kiyotaka's user avatar
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1 answer
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Why is the ketone not attacked by the Grignard reagent/cuprate in this case but a double bond is?

According to the book the answer is (a) Here I assume transmetallation occurs and then the nucleophilic carbon of methyl attacks the ring but what I don’t understand is why the ketone remains ...
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Why don't Alkyl Fluorides form Grignard Reagents

The reactivity of forming Grignards reagent were given as RI > RBr > RCl > RF and was noted that Grignard reagent with alkyl fluorides cannot be formed. What is the reason for this?
Shridp's user avatar
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Why do grignard reagents add to carbonyls at the carbonyl carbon, and not deprotonate at the alpha carbon to form an enol? [duplicate]

I thought that since grignards are such strong bases that they would be immediately protonated by the alpha hydrogen since it is an acidic hydrogen. However, I keep seeing answers that are saying that ...
Carly's user avatar
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Does Grignard reagent on reaction with PbCl2 give PbR4 and not PbR2?

I was told by my teacher that $\ce{RMgX}$ forms $\ce{PbR4}$ when it reacts with either $\ce{PbCl2/PbCl4}$ the later case is clear to me but why does $\ce{PbCl2}$ forms a compound of the form $\ce{PbR4}...
Ayush Upadhyay's user avatar
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Formation of tertiary alcohol with Ester and ONLY 1 equivalent of Grignard reagent [closed]

I don't understand how 2 methyl groups can be added to an ester to form a tertiary alcohol when I only have 1 equivalent of MeMgBr. Doesn't 1 equivalent mean that I only have 1 Methyl group that I can ...
Jacob Beaulac's user avatar
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What is the driving force of Bartoli indole synthesis?

The Bartoli indole synthesis mechanism begins with a series of attacks on the nitroarene regent by the Grignard reagents. But the atom $\ce{O}$ in $\ce{-NO2}$ should be negative, and Grignard reagent ...
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Why don’t Grignard reagants react with their alcohol products?

I’ve read that Grignard reagants react pretty quickly with alcohols and carboxylic acids to form their respective conjugate bases. I’ve also learned that Grignards can be used for the prepararion of ...
Allie's user avatar
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Sigmatropic Rearrangement along with oxidation [closed]

I was going through an organic chemistry book I came along this question it's solution used sigmatropic rearrangement along with oxidation in Jones reagent, how does this rearrangement work??
Awadhesh Prajapati's user avatar
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Mechanism of Grignard reaction with 2-(thiiran-2-yl)oxirane

What will be the final major product? The answer is 2-(methoxymethyl)-3-(substituted methyl)thiirane: I think $\ce{R}$ of $\ce{RMgX}$ attacks thiirane ring because negative charge on sulfur is more ...
Arpit Raj Choudhary's user avatar
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Why are the products of Grignard reaction on an alpha-chiral ketone diastereomers rather than a racemate?

Comment on stereochemistry of products. This is a Grignard reaction and the product has two chiral carbons. I think it should be a racemic mixture. However, my teacher says the correct answer is ...
Arpit Raj Choudhary's user avatar
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Why doesn't an acid-base reaction occur in basic amide hydrolysis instead of nucleophilic acyl substitution?

In the reaction of Grignard reagent with a primary and secondary amide, nucleophilic acyl substiution doesn't happen. The reason given is that R- is a strong base as well as strong nucleophile, an ...
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Can primary amine be produced using Grignard reagent?

I found a way to produce Secondary Alkyl Amines using Grignard Reagent. (source: wiley.com) Ref: Z. Huang, J. Lv, Y. Jia, Chemistry Select 2016, 1, 5892. DOI: 10.1002/slct.201601464 But I want to ...
K M F Ruhan's user avatar
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Preparation of tertiary Grignard reagents

Has anyone a good and detailed experimental procedure to prepare tertiary Grignard reagents from tertiary alkyl halides on the lab scale (1-5 mmol)? The actual procedures in the literature are very ...
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Would magnesium react with acyl halides to form a variant of grignard reagent just like alkyl and aryl halides?

We were having a chemistry class in our school and we were discussing the answer to some question related to acyl halides when this popped up. Our teacher mused that it may be possible but he hadn't ...
InnocentZero's user avatar
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Reaction of Grignard reagent with hydrogen cyanide

Grignard acts as a base with compounds containing acidic hydrogen: $$\ce{RMgX + R'-OH -> R-H + R'-O-Mg-X}$$ and it acts as a nucleophile with others with an electrophilic site: $$\ce{RMgX + R'-CHO -...
newbie105's user avatar
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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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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?
Soumil Gupta's user avatar
5 votes
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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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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
Prakritish Ghosh's user avatar
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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 ...
Anmoldeep's user avatar
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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 (...
Prajwal Tiwari's user avatar
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303 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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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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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 ...
David's user avatar
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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 ...
Rehearse's user avatar
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1 answer
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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 ...
Pöytä Laatikko's user avatar
5 votes
1 answer
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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. ...
Saumya Chaturvedi's user avatar
-1 votes
1 answer
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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 ...
user53617's user avatar
4 votes
1 answer
155 views

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 ...
Chem Geek's user avatar
3 votes
1 answer
638 views

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 ...
Rahul Verma's user avatar
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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 ...
Raul Luciano's user avatar
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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?
Soham Chatterjee's user avatar
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187 views

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 ...
Bornloser's user avatar
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1 answer
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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 ...
ICHO aspirant's user avatar
2 votes
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360 views

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 ...
Clara Li's user avatar
2 votes
1 answer
1k 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 ...
shreya's user avatar
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2 answers
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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 ...
Harsh18's user avatar
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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,...
Cubehacks's user avatar
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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 ...
Fallen Grenade's user avatar
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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 ...
Yashwini's user avatar
3 votes
1 answer
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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 ...
elchemiste's user avatar
1 vote
2 answers
466 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 ...
Aditya suresh's user avatar
1 vote
2 answers
163 views

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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