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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107 views

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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104 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 ...
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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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2answers
141 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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83 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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283 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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66 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 ...
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194 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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83 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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76 views

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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108 views

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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276 views

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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55 views

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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2answers
167 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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141 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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27 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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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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236 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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189 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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156 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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513 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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122 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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48 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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167 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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1answer
124 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 obvious that ester ...
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172 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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82 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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741 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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449 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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259 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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224 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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258 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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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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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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448 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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880 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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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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348 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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29 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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468 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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440 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

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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613 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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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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725 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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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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202 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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379 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 by $\ce{...