nomeclature of bicyclo تسمية المركبات bicyclo

Naming bicyclic molecules
Fused ring systems that share more than two atoms are called bicyclic molecules.
To name bicyclic alkanes, you follow these three steps:

Count the total number of carbons in the entire molecule. This is the parent name (eg. ten carbons in the system would be decane)
Count the number of carbons between the bridgeheads, then place in brackets in descending order. (eg. [2,2,1])
Place the word bicyclo at the beginning of the name.

Example: Name the following molecule by the IUPAC system of nomenclature.
nomeclature of bicyclo تسمية المركبات bicyclo Bicyclic1

Count the total number of carbons. In this case there are 7 carbons so the parent name is heptane
Count the total number of carbons between bridgeheads. In this case there are 2, 2, and 1 carbons between the bridgehead. Placed in descending order between brackets it is [2,2,1]
Put the word bicyclo in the front of the name

The name is thus bicyclo [2,2,1] heptane

Now you try naming these (click on the molecule to get the answer)
nomeclature of bicyclo تسمية المركبات bicyclo Bicyclic3

nomeclature of bicyclo تسمية المركبات bicyclo Bicyclic3

bicyclo[4,3,1] decane
nomeclature of bicyclo تسمية المركبات bicyclo Bicyclic4

bicyclo[2,2,2] octane
nomeclature of bicyclo تسمية المركبات bicyclo Bicyclic5

bicyclo[3,3,1] nonane

Bicyclic Alkanes. II. Two Ring Carbons Common.

When the two rings of the bicyclic compound have two carbons common there are three different paths between the two common carbons following carbon, carbon bonds. Take for example the following molecule:

nomeclature of bicyclo تسمية المركبات bicyclo Al0046

nomeclature of bicyclo تسمية المركبات bicyclo Al0046

In this example, the carbon atoms labeled a and b are the carbons common to the two rings, often refered to as bridgehead carbons, and the three different paths between a and b contain 1,2 and 4 intervening carbon atoms.

The generic name for compounds such as this is

bicyclo[x.y.z]alkane

where x, y, and z are the numbers of intervening carbons on the three paths between the two bridgehead carbons cited in decreasing numerical order, and alk refers to the total number of carbons in the ring systems. (For a check, this number is the sum of the three numbers, x, y, and z, plus 2 for the two bridgehead carbons.)

The compound illustrated above is thus named:

bicyclo[4.2.1]nonane

Note carefully the similarities and the differences in naming these compounds and in naming the spiro compounds.
Other named examples:

nomeclature of bicyclo تسمية المركبات bicyclo Al0047

nomeclature of bicyclo تسمية المركبات bicyclo Al0047

bicyclo[2.2.1]heptane (aka norbornane).

nomeclature of bicyclo تسمية المركبات bicyclo Al0049

bicyclo[4.3.2]undecane .

nomeclature of bicyclo تسمية المركبات bicyclo Al0050

bicyclo[4.1.0]heptane .

nomeclature of bicyclo تسمية المركبات bicyclo Decalin

bicyclo[4.4.0]decane, aka decalin .

Before proceding further, make sure that you have this basic naming system understood and learned.
Numbering the ring systems for substituent positioning

The rules for numbering the rings in these bicyclic compounds differ from those for the spiro compounds and are as follows:

Start with one of the bridgehead carbons and number it 1.

Proceed round the longest chain of carbons to the second bridgehead.

Number the second bridgehead carbon and continue on round the next longest chain of carbons back towards the first bridgehead carbon.

Pass over the first bridgehead carbon (it already has the number 1) and along the shortest chain of carbons to the second bridgehead carbon again.

Examples.
Follow the numbering of the following two compounds:

nomeclature of bicyclo تسمية المركبات bicyclo Al0047-1

for bicyclo[2.2.1]heptane (aka norbornane).

nomeclature of bicyclo تسمية المركبات bicyclo Al0050-1

for bicyclo[4.1.0]heptane .

Follow the naming of the following substituted bicycloalkanes:

nomeclature of bicyclo تسمية المركبات bicyclo Al0048

7,7-dimethylbicyclo[2.2.1]heptane.

nomeclature of bicyclo تسمية المركبات bicyclo Al0051

4-ethyl-2-isopropylbicyclo[4.1.0]heptane .

nomeclature of bicyclo تسمية المركبات bicyclo Al0052

1-methyl-8-propylbicyclo[4.3.0]nonane .

nomeclature of bicyclo تسمية المركبات bicyclo Al0053

1,9-dimethylbicyclo[4.2.1]nonane .

nomeclature of bicyclo تسمية المركبات bicyclo Al0054

2,6,6-trimethylbicyclo[3.1.1]heptane.

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