IIT JEE , AIEEE Forum - Chemistry , Organic Chemistry

Sushmi

Look at the pic and tell me what to do and how to understand the basicity order when there is a bridgehead.

Also explain your answer.

anandghegde

is itA>C>B?

newarnav

⁺In my thinking:

order of basicity should be

1st<2nd<(obviously) 3rd

Exaplanation:

For the first compd it's highly hinderd configuration restrict it to share its lone pair with any lewis acid (most probably H⁺ )

for the second compd the lone pair is involved in the resonance and hence is less availabe for shareing but still the structure is a planer one and is open to any electrophile(Lewis acid) to attack on.

third one is easier one, NO resonance and comparitively less hindered str. allows it to share its lp more easily,one more fact is that 2⁰ amines are stronger than either 1⁰or 3^0.

^{am i rite ?}

???

doucmecomin

it can be a>c>b
a unsymm+ electron density more due to more alkyl grp. atttched
c no resonance=> more electron density
b lp_singlebond_double bond res => electron spread throughot the molecule so less electron density

plz rate if usefull

anandghegde

In B lone pair is onvolved in aromatisation. Hence it is the least basic.

In A nitrogen is at the bridgehead position hence inversion stops completely(I hope you know what is inversion) Hence lone pair is available for protonation.

notice that in C there is some inversion and hence the lone pair is not completely available for protonation.

Hence it shud be A>C>B

Sushmi

Thanks i dont know the answers.

eistien

obviously the answer is A>C>B because we know B is least basic due to involvement of lone pair in resonance in A there is more +I effect on the nitrogen than in C thus increasing basicity!!!

Ask & Discuss Questions with Community & Experts