Question

#22 w/ explanation please

22. The most stable conformation of 3-bromo-2-methylpentane, viewed through the C-3-C-4 bond (i.e., C-3 in the front, C-4 in the back): CH3 (CH3)2 CH3 CH(CH3)2 CH(CH3)2 CH3 Br CH(CH3)2 CH3 CH2CH3 CH3 IV A) I B) II C) III D) IV E) V 23. An anticipated IR absorption band may not be observed because: A) the intensity is so weak that it cannot be differentiated from instrument n B) it occurs outside the range of the instrument used. C) no change occurs in the dipole moment during the vibration. D) the absorption band is eclipsed by another. E) All of these

Answer 1

From above data that staggered conformations are more step than eclipsed conformations rightarrow more stable conformation has substituting at anti - position and less no. of value integrations From option II is eclipsed, that cannot be most stable III does not have substitutes at anti - position and iv and v have more no . of gauss integrations then 1 (IV has 2 gauche Integrations) so from above options most stable conformation is 1 i. e It has only 1 gauche integration between (H_3 and Br) option A is right answer.