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Questions tagged [halides]

Chemical compounds that contain halogens (group 17 in the Periodic Table) as part of their chemical structure. This tag should only be applied where the halide group is one of the main focuses of the question.

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20
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3answers
11k views

Please explain why dioxygen difluoride is so dangerous

I just read this article that mentioned that dioxygen difluoride is very dangerous. The terms it uses are "awful", "violently hideous" and "deeply alarming". But I couldn't get a handle on exactly ...
-1
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1answer
705 views

Reagents to synthesise butanedioic acid from 1,2-dibromoethane

Why can't we use $\ce{HCN (g)}$ and $\ce{HCl (aq)}$ to convert 1,2-dibromoethane into butanedioic acid? I found out that the answer is $\ce{KCN (aq/alcoholic)}$ and $\ce{H2SO4 (aq)}$, I don't ...
6
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1answer
1k views

Mechanism for conversion of ketone to dichloride with phosphorus pentachloride

I would like to know the mechanism of this reaction leading to the formation of a geminal dichloride. I am unable to predict how the $\ce{C=O}$ breaks and how the 2 $\ce{Cl}$ atoms replace the oxygen ...
2
votes
2answers
420 views

Reactivity of primary and tertiary alkyl halides

From USNCO 2004, Q58: The reaction between which pair of reactants occurs the fastest for $[\ce{OH-}] = \pu{0.010 M}$? (A) $\ce{CH3CH2CH2CH2Cl + OH-}$ (B) $\ce{(CH3)3CCl + OH-}$ (C) $...
4
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2answers
161 views

Do alkyl halides with an alpha nitrogen atom undergo SN1 reaction?

Today, in my organic chemistry class, I learnt about the nucleophilic substitution reaction. The notes have stated that: Alkyl halides with $\alpha$ oxygen atom can also undergo SN1 reaction ...
13
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1answer
5k views

Why use potassium iodide instead of copper iodide in Sandmeyer reaction?

The Sandmeyer reaction is an extremely useful reaction for the functionalization of aromatic rings through a diazonium intermediate. For conversion of a diazonium intermediate to the corresponding ...
0
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2answers
695 views

How to calculate the percentage yield for a reaction with excess reagent?

A chemist mixed $12~\mathrm{g}$ of phosphorus with $35.5\ \mathrm{g}$ of chlorine gas to synthesize phosphorus(III) chloride (phosphorus trichloride). The yield was $42.4~\mathrm{g}$ of $\ce{PCl3}$. ...
7
votes
2answers
6k views

How can the hydrogen bonds in solid HF be best represented?

The hydrogen bonds in solid HF can be best represented as: The correct answer is supposed to be (c), but I don't understand why this is so. Does the strength of hydrogen bonding depend on the $\...
14
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3answers
4k views

Explanation for the trends in nucleophilicity—Orbital interactions or electrostatic attraction

The trend of halide nucleophilicity in polar protic solvents is $$\ce{I- > Br- > Cl- > F-}$$ The reasons given by Solomons and Fryhle[1], and by Wade[2] are basically as follows. Smaller ...
0
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0answers
40 views

What is the product when 1,4,6-trifluoroazulene is treated with sodium methoxide?

My logic During substitution via Path 1 and Path 2 aromatic intermediates are formed. Via path 3 anti aromatic intermediate is formed. Therefore reaction takes place via path 1 and path 2 only. ...
1
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1answer
2k views

Relative reactivities of alkyl halides in an E2 reaction

What is the exact order of reactivity of alkyl halides in an E2 reaction? Organic Chemistry by Paula Yurikanis Bruice says that the order is $3^\circ>2^\circ>1^\circ$. And I think this order is ...
2
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2answers
284 views

Can vicinal dihalide produce conjugated alkene in strong base?

In Klein's Organic Chemistry (3rd edition), p. 410, we learn that vicinal dihalide can produce alkyne in strong base. And on Reaxys I see many reactions of this sort. For example: However, why isn't ...
6
votes
1answer
685 views

Can an SN1 reaction occur in compounds with the leaving group attached to a primary carbon, which can later rearrange?

Can SN1 reactions occur in compounds where the carbocation, even though is is initially $1^\circ$, can rearrange to form a more stable carbocation? Examples cases:
15
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2answers
3k views

Why is cis-1,2-dichloroethene more stable than trans-1,2-dichloroethene?

Why is cis-1,2-dichloroethene more stable than trans-1,2-dichloroethene? Usually, trans compunds are more stable than cis ones, due to less strain and its non-polarity. But, in this case it's quite ...
4
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1answer
595 views

Best reagent to convert 4-chloro-4H-pyran into an aromatic compound

My question: My attempt: (I am not really good at mechanisms, so a little help would be good. Thank-you) I do not know what kind of reactions these will give.
3
votes
1answer
220 views

Stability of 3d metal fluorides and iodides in different oxidation states

I read that the fluorides of 3d metals in lower oxidation states, e.g. $\ce{VF2}$, $\ce{TiF2}$, and $\ce{CuF}$ are thermodynamically unstable. For example, $\ce{CuF}$ disproportionates to $\ce{Cu + ...
1
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0answers
31 views

Alkyl halide addition [closed]

For the above question....i did the usual addition of HF across double bonds and joined both of them and.i thought the answer would be option(b) but the answer is something else please help!!
0
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1answer
16k views

What is the hybridisation in BrF5 [duplicate]

What is the hybridisation of $\ce{BrF5}$ ? I find different sources giving different answers. When I approach this problem , I don't find any exceptional case like $\ce{SH6}$ (in which hybridisation ...
3
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0answers
213 views

Abnormal reaction of grignard reagent

My book states that: When isopropyl magnesium bromide is added to diisopropyl ketone, the expected tertiary alcohol is not obtained; instead the secondary alcohol; diisopropyl carbinol is obtained ...
11
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1answer
686 views

Order of halide nucleophilicity in DMF

The order of nucleophilicity for halide family in DMF is: $\ce{Cl- > Br- > I-}$. I understand the reason for this must be that DMF, being a polar aprotic solvent, is unable to solvate the ...
20
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3answers
350 views

Why don't alkynes undergo preferential anti bromination to the degree that alkenes do?

Alkenes, for the most part (unless there is a phenyl group or highly ionising solvent) undergo almost exclusively anti addition of bromine. However, under similar conditions alkynes, although undergo ...
1
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2answers
628 views

Metal reagent in dehalogenation of vicinal dihalides

In the dehalogenation of vicinal dihalides why can't sodium be taken as a reagent? I understand that zinc is taken because it is reactive and rate of reaction would be considerably high and it ...
1
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2answers
1k views

Is fluorine sp3 hybridized in BF3

Since BF3 has the shape of tetrahedral, and in the provided solution, Boron is sp2, why is Fluorine sp3 hybridized?
13
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1answer
260 views

Does (2-fluoroethyl)benzene undergo elimination via E1cb or E2?

I have seen in two different sources claiming that $\ce{PhCH2CH2F}$ gives styrene $\ce{PhCH=CH2}$ when treated with alcoholic $\ce{KOH}$, but one source suggests an E1cb mechanism, while the other ...
1
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1answer
844 views

Isn't the mechanism of aqueous sodium hydroxide and 1-bromobutane involves both heterolytic bond fission and attacking by a nucleophile?

What is involved in the mechanism of the reaction between aqueous sodium hydroxide and 1-bromobutane? A. attack by a nucleophile on a carbon atom with a partial positive charge B. heterolytic bond ...
1
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2answers
264 views

Does carbon monoiodide (CI) exist?

Many of my students get chlorine $\ce{Cl}$, confused with carbon monoiodide $\ce{CI}$, despite my promises to use serif fonts whenever possible and to never give them carbon monoiodide in a question. ...
5
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7answers
20k views

The solubility of haloalkanes in water

Haloalkanes aren't very soluble in water because they can't form hydrogen bonds, and the energy required to break hydrogen bonds in water etc is higher than the energy released when new bonds between ...
8
votes
1answer
666 views

Treatment of allylic alcohol with thionyl chloride: why is the product rearranged?

I have read that $\mathrm{S_Ni}$ reactions involving the attack of $\ce{SOCl2}$ on alcohols proceed without the formation of discrete carbocations, and hence there is no rearrangement involved. But ...
1
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1answer
38 views

What is the configuration of dimethyl[tris(trifluoromethyl)]-λ⁵-phosphane?

I know that $\ce{(CH3)2P(CF3)3}$ is geometry of trigonal bipyramid and according to Bent's rule $\ce{CH3}$ goes to axial positions and $\ce{CF3}$s remains on equatorial positions. However, as per ...
0
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1answer
1k views

2nd Electron Affinity of halogens

I have seen questions regarding EA but they were all about the 1st EA so this question is not duplicate. I came across a statement which goes like "2nd EA of halogens is almost zero". How is this ...
7
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1answer
2k views

What is the difference between “bromine” and “bromine water” in their reaction with an alkene?

In question 16 of the A-Level Chemistry 2013 exam, there is this reaction scheme: $$\ce{CH3CH=CH2 ->[?] CH3-CHBr-CH2Br}$$ The question asks for both the name of the reagent and the product. I ...
2
votes
0answers
454 views

Reactivity and selectivity in free radical halogenation of alkanes

I read about the free radical halogenation of alkanes with $\ce{X2}$ and I have the following questions: Given that the first step is the homolytic breaking of the $\ce{X-X}$ bond, and the homolytic ...
3
votes
0answers
48 views

Can the directionality of an SN2 reaction depend on solvent polarity?

Because of the effects of solvation, halide ions have differing nucleophilicity in protic solvents vs aprotic solvents, iodide being the best nucleophile in protic solvents and fluoride being best in ...
-1
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1answer
54 views

Can methyl halide be used in Wurtz reaction?

Yields of product(alkanes) are best for 1°(60%) and least for 3°(10%) alkyl halides. Can methyl halides be used in Wurtz reaction? Would it produce a good yield?
7
votes
0answers
901 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 ...
5
votes
1answer
3k views

Products of radical bromination and mechanism

My organic chemistry final is next Tuesday, and I have worked through the practice final. The last question is the following: Give and name all the compounds resulting from the radical monobromination ...
2
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1answer
2k views

What happens when (+) 2-iodobutane is treated with NaI in acetone?

After treating the compound with NaI, we should follow SN2 mechanism and the product will follow an optical inversion, giving us (-)2-iodobutane, but the answer is (±)2-iodobutane. After going ...
-1
votes
1answer
36 views

Will a reverse osmosis membrane exclude perfluorobutanoic acid?

I recently did a water quality test and it showed a detectable level of perfluorobutanoic acid, a potentially dangerous carboxylate PFC. Will a reverse osmosis water purification system exclude this ...
1
vote
1answer
99 views

Monobromination of napthalene derivative

How does this reaction take place? Why does the bromine attach to that one particular location? I do know that since is $\ce{FeBr3}$ is present only 1 $\ce{Br}$ will attach non-substituted areas of ...
5
votes
1answer
1k views

What is the structure of the hypothetical xenon octafluoride?

According to Frlec et al.,[1] theoretical studies indicated that there is a possibility (albeit slim) that neutral xenon octafluoride ($\ce{XeF8}$) might exist. I am curious as to what structure this ...
5
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1answer
2k views

How can I choose the correct mechanism for nucleophilic substitution of aryl halides?

I was reading about nucleophilic substitutions of aryl halides, and there are three different mechanisms discussed, namely the SN1, SNAr (addition-elimination), and benzyne (elimination-addition) ...
6
votes
1answer
123 views

If liquid hydrogen fluoride autoionises, how can it be an insulator?

According to Wikipedia, one of the last major hurdles in the isolation of elemental fluorine was the need to mix hydrogen fluoride with another substance in order for its electrolysis to be possible (...
2
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0answers
56 views

Why do reactions of sodium halides with sulfuric acid produce sodium hydrogen sulfate instead of sodium sulfate?

In the reaction of sodium halides with sulfuric acid, sodium hydrogen sulfate is produced \eqref{NaHSO4}. Why would this be produced instead of sodium sulfate \eqref{Na2SO4}? \begin{align} \ce{NaX + ...
5
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1answer
5k views

Why do sodium halides react so differently with sulfuric acid?

Why do sodium halides react so differently with sulfuric acid? \begin{align} \ce{NaF + H2SO4 &-> NaHSO4 + HF} \tag{1a}\label{NaF}\\ \ce{NaCl + H2SO4 &-> NaHSO4 + HCl} \tag{...
11
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1answer
2k views

Why does treatment of a geminal dihalide with sodium amide lead to an alkyne and not an allene?

I've come across the following problem in Klein's Organic Chemistry, 2nd edition: However, I'm a little bit confused about why the terminal alkyne is produced. I believe that an allene should be ...
1
vote
1answer
273 views

What's the difference between FFKM and PTFE?

These two fluorocarbon polymers seem to me very similar, the only difference I see is that FFKM is elastomer while PTFE aka Teflon is more of hard type of plastic. Isn't FFKM just PTFE with lower ...
44
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8answers
27k views

Why do compounds like SF6 and SF4 exist but SH6 and SH4 don't?

Both $\ce{SF6}$ and $\ce{SH6}$ and $\ce{SF4}$ and $\ce{SH4}$ have the same central atom and the same hybridization, but my teacher specifically mentioned that $\ce{SH6}$ and $\ce{SH4}$ don't exist. I'...
1
vote
1answer
476 views

Wurtz Reaction with acidic alkyl halides [closed]

My chemistry book says we cannot use alkyl halides containing acidic hydrogen for Wurtz reaction. Why is this so?
8
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2answers
1k views

Why does chlorination of toluene stop at two chlorine atoms?

My instructor mentioned a reaction for preparation of benzaldehyde by chlorination of toluene in presence of sunlight to form benzal dichloride, which on hydrolysis gives benzaldehyde. However, I'm ...
10
votes
1answer
836 views

Mechanism of lithium-halogen exchange of primary alkyl iodide

On Clayden's page 190 this reaction is given for preparation of organometallics: What is the mechanism of this reaction? I expected the "almost carboanion" part of the $\ce{t-BuLi}$ to attack as a ...