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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1answer
68 views

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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1answer
20 views

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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1answer
43 views

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 ...
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1answer
64 views

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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2answers
105 views

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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71 views

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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1answer
265 views

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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76 views

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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1answer
166 views

Grignard reaction on electron-poor benzyl bromides

I am trying to prepare a Grignard reagent from 4-nitrobenzyl bromide but the reaction just doesn't work. My conditions are: 10 mL of THF (anhydrous); 7.04 mmol of 4-nitrobenzyl bromide; 7.04 mmol of ...
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42 views

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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1answer
122 views

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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67 views

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 ...
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2answers
823 views

Reaction of coumarin with phenylmagnesium bromide

I came across this problem.. I thought that the Grignard reagent, PhMgBr, would cleave the lactone and then subsequently add to the ketone formed, giving an allylic tertiary alcohol after aqueous ...
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1answer
122 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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1answer
80 views

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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1answer
268 views

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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1answer
245 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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1answer
162 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 ...
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109 views

Is it possible to obtain n-butane by treating halopropane grignard reagent with methanol?

The answer is a,b. My mechanism however doesn't give n-butane when R is propyl. Is this a case of textbook errata? Himanshu Pandey, Advanced Problems In Organic Chemistry, 9th edition ...
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1answer
3k views

Grignard Reagent in THF vs in Diethyl ether

While learning about the Grignard reagent I was taught this by my teacher, but I couldn’t justify why it was so.. I cannot see how Grignard reagent would react differently in basically an ethereal ...
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0answers
546 views

Why might the yield of my synthesis of triphenylmethanol be so poor?

I performed the classic Grignard reagent formation leading into the preparation and purification of triphenylmethanol using phenylmagnesium bromide as my Grignard, and benzophenone as the reagent for ...
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1answer
468 views

Ring contraction when cyclohexene oxide is treated with methyl Grignard

My book writes that: Recall that epoxides rearrange with Lewis acids in a pinacol-like fashion, and that Grignard reagents in THF exist in the following equilibrium: I approached this ...
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241 views

Steric Factors on reaction with grignard reagent

I was asked to find the products X and Y. For the product X,Here the grignard reagent and even the carbonyl substrate was too sterically hindered to approach the carbonyl center so no reaction would ...
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1answer
4k views

What is the role of ammonium chloride in the workup of a Grignard reaction?

In the following Grignard reaction, why is aqueous ammonium chloride used to get to the products? I don't see how it participated in or modified the reaction from what is normally expected.
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1answer
312 views

How does Grignard reagent form? [duplicate]

So I've read that during the formation of the Grignard reagent, The R-X bond cleaves homolytically forming free radicals. My question is how is this happeneing? Due to the high electronegativity ...
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1answer
27 views

Chain elongation with a substituent

Can this compound exist in a stable form. If so, can it be used to add the chloroethyl group to a carbonyl compound
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287 views

Is HMgX also a Grignard Reagent like RMgX?

We do know that the Grignard Reagent is $\ce{RMgX}$ where R is some alkyl group & X is any halogen group. So, my question is that, whether $\ce{HMgX}$ is also a Grignard Reagent like $\ce{RMgBr}$?
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1answer
359 views

Can thiols be created using a Grignard reagent?

I'm trying to find information on the synthesis of thiols via Grignard reagents. While looking at the synthesis routes on Wikipedia, it said that a Grignard reagent will react with sulphur to form ...
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1k views

Why does magnesium prefer to insert into C–Br bonds over C–Cl bonds?

In the formation of a Grignard reagent from a compound possessing both bromine and chlorine, magnesium preferentially inserts into the C–Br bond over the C–Cl bond. For example, the formation of a ...
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1answer
597 views

Why do Grignard reagents add to propargyl alcohols?

In Phil Baran's lectures on heterocyclic chemistry at Scripps, one of the lecture problems is concerned with this synthesis of Vioxx: The first step supposedly involves an anti addition of the aryl ...
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1answer
740 views

Compatibility of Grignard reagents with aromatic nitro groups [closed]

Is it possible to form a Grignard reagent from 1-chloro-3-nitrobenzene, as shown below? Specifically, will the nitro group react with the Grignard reagent formed?
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1answer
438 views

Rearrangement of Grignard reagent formed from exocycloproyl vinyl bromide

First, I prepared the grignard reagent then performed nucleophilic addition to the carbonyl carbon and then did hydrolysis. So basically in my product, $\ce{-Br}$ is replaced by $\ce{-CH2OH}$ But ...
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1answer
2k views

Which alkyl halides can not form grignard reagent [closed]

Which compounds are not useful for preparation of grignard reagents? a) 4-chlorobut-1-yne b) 2-chloroethan-1-amine c) 1-bromobutan-2-ol d) 4-bromocyclohexan-1-ol
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1answer
524 views

Reactions of Grignard Reagent: 1,2 vs 1,4 addition

So I was reading through Grignard reagent and I came across this answer by jerepierre, which mentions: In general, Grignard reagents and organolithium reagents add directly to the carbonyl carbon, ...
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1answer
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Reaction of Grignard reagent with primary amines

What does the reaction $\ce{CH3CH2NH2 + CH3MgBr ->}$ form? Does it form a secondary amine or a tertiary amine or an alcohol? I can't find what a Grignard reagent does to a primary amine.
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148 views

What will be the product of this reaction?

We have an alpha beta unsaturated ether, along with a keto group in the same compound, which is being treated with a grignard reagent shown (assume the grignard reagent is in excess). Will it only ...
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1answer
242 views

Reaction of carbonyl cyclic diene with Grignard reagent

Predict the major product of this reaction: The two compounds on the right are the possibilities that I thought of (weren't given in the question). According to me: attack on carbonyl carbon ...
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2answers
5k views

What are the pros and cons of using Gilman reagent over Grignard reagent to synthesize a hydrocarbon?

As far as I know, in order to synthesize a hydrocarbon $\ce{R-R'}$, Grignard reagent or Gilman reagent could be used. $\ce{RMgX + R'X -> RR' + MgX2}$ $\ce{R2CuLi + R'X -> RR' + LiX + RCu} $ ...
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Does grignard reagent react with oxygen?

Does this reaction actually take place - $$\ce{C2H5MgCl + O2 ->[H2O] C2H5OH}$$ I never saw this kind of a reaction. I thought that grignard reagent might take a proton from water and just form ...
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1answer
381 views

Preparation of an aromatic Grignard reagent

I was tasked with preparing 4-fluorophenylmagnesium chloride from the corresponding aryl chloride. But I've heard that aryl Grignard reagents are very difficult to prepare. I think that the optimal ...
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1answer
182 views

The reactions of grignard reagent

Question Find y in this question : The $\ce{ -CH2-Cl}$ below according to me will not take part the reaction (or please correct me) thus my answer is y=2 but actually it's y=3
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4k views

Phenol preparation from Grignard reagent

Reaction: Phenyl magnesium bromide in presence of excess oxygen, on acidification yields phenol, as below. My instructor told me that the above reaction occurs, and if the reagent is in excess then ...
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3answers
468 views

Conversion from t-butanol to alkene

How can I accomplish the above conversion? My thoughts: One way of introducing the double bond, would be using the appropriate Grignard Reagent after oxidation of t-butanol (somehow) I think that ...
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2answers
1k views

Getting 3,4-dimethylhex-3-ene from but-2-ene

How can one get 3,4-dimethylhex-3-ene from but-2-ene ? $\hskip2in$ Using $\ce{Br_2}$ then two equivalents of $\ce{CH_3CH_2MgBr}$, I can get the corresponding alkane (3,4-dimethylhexane) but I don't ...
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711 views

Mechanism for reaction of an allene with the Grignard Reagent(RMgX)

How does the Grignard Reagent($\ce{RMgX}$) react with an allene $\ce{CH_2=C=CH_2}$ and what are the products formed? This is exactly what I tried to do. Any help will be appreciated.
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1answer
106 views

Grignard Reagent and Ester [closed]

Is this answer wrong? I feel like there should be a hydrogen instead of a carbon where I indicated in red. Thank you.
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100 views

Leaving group stability when treated with grignard

Why does $\ce{-NH2}$ not leave in $\ce{RCONH2}$ while in $\ce{RCONR2}$ $\ce{NR2}$ leaves when treated with Grignard? I thought $\ce{NH2}$ should leave as there negative charge is more stable on $\ce{N}...
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1answer
558 views

Why do orthoesters react with Grignard reagents, but acetals and ketals don't?

My book mentions the synthesis of aldehydes and ketones using alkyl ortho esters. It's called Bodroux-Chichibabin aldehyde synthesis. Now, later, the book mentions this: R- displaces EtO-, giving ...
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1answer
335 views

Stereochemistry of product in Grignard-Gilman addition reaction

I would like to know whether the stereochemistry given in the following reaction is correct or not? Which attack is more likely? axial or equatorial? I think I should say pseudo axial or pseudo ...
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1answer
327 views

Why is a Grignard reagent not protonated by chloramine?

When $\ce{RMgX}$ (Grignard reagent) reacts with chloramine ($\ce{NH2Cl}$) it forms $\ce{RNH2}$. But why doesn't it form $\ce{RH}$ by taking a hydrogen atom from chloramine as the negative charge so ...