E-Z Nomenclature rules SEQUENCE RULE 1: If the four atoms directly attached to the double bond are all different, priority depends on atomic number, with the atom of higher atomic number receiving the higher priority. COROLLARY: If two atoms are isotopes of the same element, the heavier isotope receives the higher priority. LIYING 2021/2/10
LIYING 2021/2/10 E-Z Nomenclature Rules ❖SEQUENCE RULE 1: If the four atoms directly attached to the double bond are all different, priority depends on atomic number, with the atom of higher atomic number receiving the higher priority. ❖COROLLARY: If two atoms are isotopes of the same element, the heavier isotope receives the higher priority
E-Z Nomenclature rules SEQUENCE RULE 2: If the relative priority of two groups cannot be decided by Rule l, it shall be determined by a similar comparison of the next atoms in the groups (and so on, if necessary), working outward in ranks from the double bond LIYING 2021/2/10
LIYING 2021/2/10 E-Z Nomenclature Rules ❖SEQUENCE RULE 2: If the relative priority of two groups cannot be decided by Rule 1, it shall be determined by a similar comparison of the next atoms in the groups (and so on, if necessary), working outward in ranks from the double bond
E-Z Nomenclature rules To complete the Iupac name of a particular isomer, enclose the(e)or Z)symbol in parentheses and place it at the front of the entire name of the compound. Separate the(e)or(z symbol from the rest of the name with a hyphen LIYING 2021/2/10
LIYING 2021/2/10 E-Z Nomenclature Rules ❖To complete the IUPAC name of a particular isomer, enclose the (E) or (Z) symbol in parentheses and place it at the front of the entire name of the compound. Separate the (E) or (Z) symbol from the rest of the name with a hyphen
H2C CCH H CHOCH CH3(C) C2H5(第二原子:CH,H CH2>H CH第二原子:HHH C2H5>CH3 (E)-3-甲基-2-戊烯 Question:(CH3)3C-与 CH2C哪个为优先基团? LIYING 2021/2/10
LIYING 2021/2/10 C C H3C H CH3 CH2CH3 CH3 (C) CH3 >H C2H5 (第二原子：C,H,H) CH3 (第二原子：H,H,H) C2H5 >CH3 (E)-3-甲基-2-戊烯 Question: (CH3 )3C-与 -CH2Cl哪个为优先基团？
CH 3 CH3=CH=CH一CH2-CH H CH3-CH2-CH CH 3 trans-6-Methyl-3-propyl-2-octene LIYING 2021/2/10
LIYING 2021/2/10 C C CH3 H CH2 CH2 CH3 CH2 CH2 CH CH2 CH3 CH3 trans-6-Methyl-3-propyl-2-octene