Rank the substituents in each of the following sets...

Rank the substituents in each of the following sets according to the sequence rules: (a) $-\mathrm{CH}_{3},-\mathrm{OH},-\mathrm{H},-\mathrm{Cl}$ (b) $-\mathrm{CH}_{3},-\mathrm{CH}_{2} \mathrm{CH}_{3},-\mathrm{CH}=\mathrm{CH}_{2},-\mathrm{CH}_{2} \mathrm{OH}$ (c) $-\mathrm{CO}_{2} \mathrm{H},-\mathrm{CH}_{2} \mathrm{OH},-\mathrm{C} \equiv \mathrm{N},-\mathrm{CH}_{2} \mathrm{NH}_{2}$ (d) $-\mathrm{CH}_{2} \mathrm{CH}_{3},-\mathrm{C} \equiv \mathrm{CH},-\mathrm{C} \equiv \mathrm{N},-\mathrm{CH}_{2} \mathrm{OCH}_{3}$

Rank the substituents in each of the following sets according to the sequence rules:
(a) $-\mathrm{CH}_{3},-\mathrm{OH},-\mathrm{H},-\mathrm{Cl}$
(b) $-\mathrm{CH}_{3},-\mathrm{CH}_{2} \mathrm{CH}_{3},-\mathrm{CH}=\mathrm{CH}_{2},-\mathrm{CH}_{2} \mathrm{OH}$
(c) $-\mathrm{CO}_{2} \mathrm{H},-\mathrm{CH}_{2} \mathrm{OH},-\mathrm{C} \equiv \mathrm{N},-\mathrm{CH}_{2} \mathrm{NH}_{2}$
(d) $-\mathrm{CH}_{2} \mathrm{CH}_{3},-\mathrm{C} \equiv \mathrm{CH},-\mathrm{C} \equiv \mathrm{N},-\mathrm{CH}_{2} \mathrm{OCH}_{3}$

Key Concepts

CIP Priority Rules

The Cahn-Ingold-Prelog (CIP) system provides a set of rules for ranking substituents attached to a stereocenter. It is crucial for assigning stereochemical configurations (R/S and E/Z) by comparing atoms sequentially based on their atomic numbers and connectivity.

Atomic Number Comparison

At the core of the CIP rules is the comparison of atomic numbers of the atoms directly attached to the stereocenter. A substituent with an atom of higher atomic number is given priority over one with a lower atomic number, making this step essential in determining substituent order.

Treatment of Multiple Bonds

In the CIP system, multiple bonds are treated as if the bonded atoms are duplicated. For example, a double bond is considered as two single bonds to the same type of atom. This approach allows for a meaningful comparison of substituents that contain multiple bonds.

Sequential Comparison of Substituents

When the atoms directly attached to the stereocenter are identical, the CIP rules require a stepwise examination of the next set of atoms along each substituent's chain. This sequential approach continues until a point of difference is found, ensuring an unambiguous ranking of the substituents.

Transcript

00:01 Sequence rules are used to determine the ez notation and also the rs configuration.

00:08 So for sequence rule we have to first of all determine the atomic number of each atom which is at the point of attachment.

00:18 Okay, so first of all we have given here ch3 -o -h substituent, then h -substituent, then h -substituent, and then cl substituent.

00:34 So we will determine here atomic numbers for each of them for the point of attachment atom.

00:41 So now for ch3, i have carbon atom here and carbon has six atomic number.

00:50 For oh i have oxygen at the point of attachment and for oxygen we have eight atomic number.

00:57 For hydrogen, so that is present at the point of attachment and we have one atomic number.

01:03 Number for chlorine we have 17 atomic number okay so for this reason increasing order for substituents so that we have first of all cl okay so cl then we have this then we have this oh group cl substituent then then oh substituent then we have ch3 substituent and then in the last we have this hydrogen substituent okay so that will be the order now b part so this time we have ch3 ch2 ch3 then we have che double bond ch2 and then we have ch2 oh.

02:50 In this case all the substituents we have so they have carbon atom at the point of attachment.

02:57 Okay.

02:58 So now when we have same kind of atoms present at the point of attachment then we consider the rest of the atoms it is attached to.

03:09 Okay.

03:09 So now, so in ch3 carbon is attached to three hydrogen atoms in ch2, the carbon is attached to one carbon atom in c.

03:49 Ch double bond ch 2 in this case 2 in this case we have double bonds okay so this double bond is counted as to two individual bonds okay so in that case we will see we will say that to two carbon and one hydrogen atom and in in ch2 oh so carbon is attached to 3 hydrogen and 1 oxygen atom okay so now we will consider the atomic number so substituent ch2 oh will be in first place because here we consist of oxygen atom and that has the more atomic number rest of these and then we will consider ch double bond ch 2 because here we have double bond and that is considered as 2 carbon atom okay and then we have then we have ch2 ch3 because it consists of more carbon atoms and more hydrogen atoms in comparison to ch3 okay, so this will be the order.

05:43 Now, c part.

05:47 So we have c -o -2 -h.

05:50 That can also be written as c -o -h, right? and c -h -2 -o -h and c -t -w -triple bond n and c -h -2...

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