Shweta thakur Asked a Question
May 3, 2020 3:00 pmpts 30 pts
mageS aae ITO 2.5. RELATIVE STABILITIES OF DIENES-STRUCTURE OF 1, 3-BUTADIENE Heats of hydrogenation can be used to determine the relative stabilities of dienes. We know that alkenec with similar structures have approx. the same value of heat of hydrogenation. For mono substituted alkenes RCH CH,), it is approx. 125-4 kJ/mole, for disubstituted alkenes, (RCH = CHR or R,C = CH,), it is about 117-1 kJ/mole and for trisubstituted alkenes (R,C = CHR), it is about 112.9 kJ/mole. For a compound having more than one double bond, it is reasonable to expect a heat of hydrogenation which is the sum of the heat of hydrogenation of the individual double bonds. Let us consider, the heats of hydrogenation of 1, 3-pentadiene (a conjugated diene) and 1, 4-pentadiene (an isolated diene). Xottu 2 3 4 5 CH, = CHCH = CHCH+ 2H, 1,3-Pentadiene Ni CH CH,CH,CH,CH n-Pentane Found : AH =- 226-2 kJ mol- AM Calculated: AH = (117.1 + 125-4) = - 2425 kJ mol 2 5 CH,=CH ČH, CH=CH, + 2H Ni CH,CH,CH,CH,CH 1,4-Pentadiene n-Pentane Found: AH =-254-2 kJ mol- Calculated: AH = - 2x 125.4 =-250-8 kJ mno o-
  • 1 Answer(s)
  • 0 Likes
  • 1 Comments
  • Shares
  • Suresh khokhar thankyou
    due to resonance 1 3 butadiene is more stable as comparison to 1,4 penta diene
    Likes(0) Reply(0)
Head Office :
MPA 44, 2nd floor, Rangbari Main Road,
Mahaveer Nagar II, Kota (Raj.) – 324005

Corporate Office:
212, F-1, 2nd Floor, Evershine Tower,
Amrapali Marg,
Vaishali Nagar, Jaipur (Raj.) – 302021

Mail: info@eduncle.com
All Rights Reserved © Eduncle.com