DAT Destroyer #108

[Dental_14]

I don't really understand why Bromine would be considered a spectator ion and then Florine wouldn't be. And also why Nitrate would be considered a spectator ion and then Carbonate wouldn't be either. Why wouldn't they react in a similar fashion.

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[DAT Destroyer]

I don't really understand why Bromine would be considered a spectator ion and then Florine wouldn't be. And also why Nitrate would be considered a spectator ion and then Carbonate wouldn't be either. Why wouldn't they react in a similar fashion.

You have asked a VERY IMPORTANT question. Lets review the strong acids,,,, HI, HBr, HCl, HNO3, H2SO4, and HCLO4 are the most common..... For bases Hydroxides of Na, Li, K, Cs, Rb, Ca, Ba, and Sr. Now....anions of strong acids are VERY WEAK.......thus will not react with water.......hence are called spectators. Thus Br- is a spectator.....it is the anion of HBr.....NO3- is also weak,,,,,it is the anion of the super strong acid Nitric ,,,HNO3. Now.....F- is not a spectator,,,,,since it is not derived from a strong acid, namely HF......HF is not considered a strong acid. Consequently, F- would indeed react with water to produce HF and OH-.

I hope this helps.....If you still need clarity......Zumdahl, Chang, Brady and Ebbing do a splendid job explaining this in their textbooks.

Dr. Romano

 

[Dental_14]

Thank you very much, that cleared it up.
Also, I wanted to ask about stability of carbocations and radicals. I understand the an allylic radical would be more stable than a tertiary radical but this also apply to carbocations? Or would a tertiary carbocation be more stable that an allylic carbocation?
@orgoman22

 

[DAT Destroyer]

Thank you very much, that cleared it up.
Also, I wanted to ask about stability of carbocations and radicals. I understand the an allylic radical would be more stable than a tertiary radical but this also apply to carbocations? Or would a tertiary carbocation be more stable that an allylic carbocation?
@orgoman22

It turns out .....no ! Experimentally...... a Tertiary carbocation beats out a primary allylic carbocation ......which is slightly less stable than a secondary carbocation. How is a tertiary carbocation beat ? Species such as Aromatic cations !!!!!
This order is not the same for radicals...
For radicals...... Benzylic >allylic>tertiary.secondary>primary

Professors may have told you a slightly different ordering. The stability of these intermediates is not so easy to measure. I have cited the newest order using Smith-March Advanced Organic Chemistry text as my reference...2013 edition.

I hope this helps !

Dr. Romano

 

[Dental_14]

Thank you again for the clarification, appreciate it.