Why is water nucleophile

So we can see that it has two properties that would favor nucleophilicity, but its not the best nucleophile. Thus in the the absence of a better nucleophile, the water molecule can act as a nucleophile. Also, in the grand scheme of a reaction, it can be used to go from a greater relative energy state to a lower energy state, thus the interaction with water is going to be favorable. Jump to. The back of the molecule is completely cluttered with CH 3 groups.

In the first stage, a small proportion of the halogenoalkane ionises to give a carbocation carbonium ion and a bromide ion. This reaction is possible because tertiary carbocations are relatively stable compared with secondary or primary ones. Even so, the reaction is slow. Note: Not sure about the stability of carbocations carbonium ions? Follow this link if you need to find out. Once the carbocation is formed, however, it would react immediately it came into contact with a water molecule.

One of the lone pairs on the water is strongly attracted towards the positive carbon, and moves towards it to create a new bond. How fast the reaction happens overall is going to be governed by how fast the halogenoalkane ionises - because that's a slow process. Because this initial slow step only involves one species, the mechanism is described as S N 1 - substitution, nucleophilic, one species taking part in the initial slow step.

The water takes part in the fast step of the reaction, and so the fact that a weakish nucleophile like water is involved doesn't significantly slow the overall reaction down.

The rate is determined by the slow ionisation of the halogenoalkane. As with primary halogenalkanes, there is a final stage to this reaction in which a hydrogen ion is transferred from the organic ion to a water molecule in the solution.

What happens is exactly the same as with the primary halogenoalkanes described above. The reaction between primary halogenoalkanes and water - the S N 2 mechanism Water as a nucleophile A nucleophile is a species an ion or a molecule which is strongly attracted to a region of positive charge in something else.

Use the BACK button on your browser to return to this page. The high electronegativity of oxygen stabilizes the electrons of oxygen making it a poor nucleophile. The hydrogen of water on the other hand, is induced electrophilic, due to the highly electronegative oxygen. The electrophilic potential of hydrogen is strong enough to withdraw electron density from the poor nucleophile oxygen aspect of water to form a hydrogen bond. Pages: [ 1 ] Go Up.

Sponsored Links. The product will include a Br and Hydroxy group Halohydrin Formation. Sign up to join this community. The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Learn more. Is water a better nucleophile than bromide? Ask Question. Asked 6 years, 9 months ago. Active 3 years, 11 months ago. Viewed 5k times.

The question is, was my professor wrong or is there something I'm missing? Thank you very much. Improve this question.