Nomenclature of Bridge Compounds in Organic Chemistry
Understanding the nomenclature of bridge compounds is essential in organic chemistry. This involves defining bridge heads, bridges, main ring selection, main bridge heads, main bridges, secondary bridges, and more. The IUPAC nomenclature of bridge systems includes indicating the number of rings using prefixes, numbering atoms, and naming hydrocarbons with specific bridge configurations. Learn the rules and examples to name bridge compounds accurately.
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Nomenclature of Bridge Compounds Dr. Snigdha Roy Assistant Professor Department of Chemistry B. B. College Asansol Asansol-713303
Bridge Compounds Some Important Definitions Bridge head atom: A bridge head is any skeletal atom of the ring system which is bonded to three or more skeletal atoms (excluding hydrogen). Bridge heads are common to all the rings. Bridge: A bridge is an unbranched chain of atoms or an atom or a valence bond connecting two bridge heads. Main Ring of Polycyclic system is selected in such a manner so that it includes as many skeletal atoms of the polycyclic compound as possible. Main bridge heads: These bridge heads must be linked by at least 3 bridges. Main bridge: The main bridge connects between two main bridge heads. Secondary Bridge is any bridge not included in the main bridge or in the main ring. Independent secondary bridge links bridge head which are part of the main ring or main bridge. Dependent Secondary Bridge links at least one bridge head which is a part of secondary bridge.
Example: The following compound contains seven carbon atoms is, therefore, a bicycloheptane.
IUPAC Nomenclature of Bridge System Indicate the number of rings using the prefix bicyclo- , tricyclo- etc. Examine the bridge lengths. Number the atoms starting from a main bridge head following the longest bridge of the main ring of the polycyclic system to reaching at the other bridge head position. Complete the counting by putting the last numbers sequentially on the smallest bridge of the compound. Interpose in the name an expression in square brackets that denotes the number of carbon atoms in each bridge (in order of decreasing length) excluding the bridge heads. So, here, the name of the hydrocarbon would be like the following: It indicates the total number of skeletal atoms i.e. 8 (or octane) Three bridges are there, in decreasing order of size that would be [3.2.1].
IUPAC Nomenclature of Bridge System Suffix including functional group (-COOH, Ketone, C=C etc.) [ a . b . c . d ] [placed in decending Order i.e. a>b>c>d] Parent alkane General Naming Rule: Compound Type (bicyclo/tricyclo etc.) 10 7 4 4 5 1 1 1 1 Bicyclo[4.1.1]octane Bicyclo[2.2.1]heptane Bicyclo[3.3.3]undecane Bicyclo[3.2.1]octane 9 1 5 3 8 1 Bicyclo[1.1.1]pentane Tricyclo[3.2.1.02,4]octane Bicyclo[3.3.1]nonane
IUPAC Nomenclature of Bridge System If substituents are present, number the bridged ring system starting from one bridgehead proceeding first along the longest bridge to the other bridgehead, then along the next longest bridge back to the first bridgehead. The shortest bridge is numbered last. Suffix including functional group (-COOH, Ketone, C=C etc.) 7 [ a . b . c . d ] Parent Alkane [placed in descending Order i.e. a>b>c>d] Prefix Substituent attached Compound Type (bicyclo/tricyclo etc.) 1 7 9 4 1 6 7 1 2 8 3 8 1 Tricyclo[2.2.1.02,6]heptane 3 Bicyclo[3.2.1]oct-2-ene 9-Methyl-bicyclo[4.2.2]dec-7-ene #7: Please note: Von Baeyer name suggested for a ring which is not yet in dictionary Tricyclo[4.2.1.03,8]nonane
IUPAC Nomenclature of Bridge Compounds H N 3 OMe O 1 1 5 3 3-Oxa-9-aza-tricyclo[3.3.1.02,4]nonane OMe 1,3-Dimethoxy-bicyclo[2.2.1]heptane 1 O O 2 7 4 NH 5 2-Oxa-4-aza-bicyclo[3.2.1]octane Bicyclo[2.2.1]hept-5-en-2-one
