6
$\begingroup$

I'm currently learning about substitution and elimination reactions and to do so I need to learn about bases and nucleophiles.

Apparently a good base is an unstable species.

What does stability even mean in chemistry?

I just need to conceptually understand and wrap my head around this concept of a compound or atom or species being 'stable' or 'unstable'. Please don't explain it in complicated terms.

$\endgroup$
  • 3
    $\begingroup$ Thinking about something as being 'stable' or 'unstable' is often misleading as stability can depend on many things. Esters, for instance, may be perfectly 'stable' if left out in a vial, but incredibly unstable if stirred in a flask with some aqueous base. Stability should, therefore, always be qualified, for instance thermodynamic stability and kinetic stability are both terms often considered by chemists. $\endgroup$ – NotEvans. Nov 12 '15 at 23:54
  • $\begingroup$ And to take @NotNicolaou’s comment a step further, kinetic ‘stability’ should not be called ‘stability’ at all but better inertness. $\endgroup$ – Jan Dec 25 '15 at 22:37
2
$\begingroup$

Stability has several meanings. A compound can be stable on its own, under the given conditions such as temperature and pressure. This is the case for a lot of compounds. The other definition of stable could be a compound's inability to react with other molecules (like the inability of carboxylic acids to be oxidized). This is probably what you meant. A good base, like $R-O^-$ is unstable because of the +I effect of the alkyl group, which shifts the electron density towards oxygen, which in turn makes the ion a very good and strong nucleophile. This is the reason why such "good bases" tend to cause eliminations and substitutions in organic molecules.

P.S.: This is the simplest explanation I can provide. If you have any doubts, ask them in the comments.

P.S.S.: Stability of a compound can also be explained on the basis of what @NotNicolaou said.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.