النتائج 1 إلى 3 من 3

الموضوع: Structure of Benzene

  1. #1
    عضو ذهبي الصورة الرمزية ماجده
    تاريخ التسجيل
    Aug 2011
    الدولة
    Jordan - Zerqa
    المشاركات
    901

    افتراضي Structure of Benzene

    Benzene represents a special problem in that, to account for all the bonds, there must be alternating double carbon bonds



    The various representations of benzene




    X-ray diffraction shows that all of six carbon-carbon bonds in benzene are of the same length of 140 picometres (pm). The C–C bond lengths are greater than a double bond (135 pm) but shorter than a single bond (147 pm). This intermediate distance is consistent with electron delocalization: the electrons for C–C bonding are distributed equally between each of the six carbon atoms.
    The molecule is planar.
    One representation is that the structure exists as a superposition of so-called resonance structures, rather than either form individually. The delocalization of electrons is one explanation for the thermodynamic stability of benzene and related aromatic compounds. It is likely that this stability contributes to the peculiar molecular and chemical properties known as aromaticity
    . To indicate the delocalized nature of the bonding, benzene is often depicted with a circle inside a hexagonal arrangement of carbon atoms



    The delocalized picture of benzene has been contested by Cooper, Gerratt and Raimondi in their article published in 1986 in the journal Nature. They showed that the electrons in benzene are almost certainly localized, and the aromatic properties of benzene originate from spin coupling rather than electron delocalization. This view has been supported in the next-year Nature issue, but it has been slow to permeate the general chemistry community.

    As is common in organic chemistry, the carbon atoms in the diagram above have been left unlabeled. Realizing each carbon has 2p electrons, each carbon donates an electron into the delocalized ring above and below the benzene ring. It is the side-on overlap of p-orbitals that produces the pi clouds.

    Derivatives of benzene occur sufficiently often as a component of organic molecules that there is a
    Unicode symbol in the Miscellaneous Technical block with the code U+232C (⌬) to represent it with three double bonds, and U+23E3 for a delocalized version.

    عضو في نادي ماركا الأكاديمي


  2. #2
    عضو مميز الصورة الرمزية قمر بلحاج
    تاريخ التسجيل
    Jul 2012
    المشاركات
    5,302

    افتراضي رد: Structure of Benzene

    جزاكم الله خيرا

    عضو في نادي ماركا الأكاديمي


  3. #3
    مراقب عام الصورة الرمزية Eiman
    تاريخ التسجيل
    Jul 2011
    الدولة
    الاردن - ماركا
    المشاركات
    14,750

    افتراضي رد: Structure of Benzene

    شكرا جزاكم الله خيرا ....
    من جد وجد ....... ومن سار على الدرب وصل

معلومات الموضوع

الأعضاء الذين يشاهدون هذا الموضوع

الذين يشاهدون الموضوع الآن: 1 (0 من الأعضاء و 1 زائر)

الكلمات الدلالية لهذا الموضوع

المفضلات

ضوابط المشاركة

  • لا تستطيع إضافة مواضيع جديدة
  • لا تستطيع الرد على المواضيع
  • لا تستطيع إرفاق ملفات
  • لا تستطيع تعديل مشاركاتك
  •