Do the following compounds have the E or the Z...

Key Concepts

Geometric Isomerism

Geometric isomerism refers to the type of stereoisomerism that arises due to the restricted rotation around a double bond or ring structure, resulting in different spatial arrangements of substituents. In the context of alkenes, it manifests as E (entgegen) and Z (zusammen) configurations, which depend on whether the highest priority substituents on the carbon atoms are on opposite or the same side of the double bond. This concept is fundamental in understanding the three-dimensional structure of molecules and their different physical and chemical properties.

Cahn-Ingold-Prelog Priority Rules

The Cahn-Ingold-Prelog (CIP) priority rules are a systematic method used to assign priorities to the substituents attached to the stereocenters or double bonds in molecules. In the context of determining E or Z configurations, the rules help identify which substituents have higher priority based on atomic numbers and bonding environments, allowing for a consistent method to designate the spatial orientation of the groups around a double bond. This method is crucial for ensuring clarity and consistency in the communication of stereochemical information.

Transcript

00:01 To determine whether these molecules are e or z configuration, we will identify the groups that have the highest priority on each of the carbons involved in the double bond.

00:16 So starting with part a, the groups on the left are attached to this left carbon.

00:22 The one of the highest priority will be this group at the top, since it's a two -carbon chain and the one on the bottom has just one carbon.

00:31 Looking at the groups from the carbon on the right, the group with the highest priority, we're the group with the chlorine, since chlorine is a higher atomic number, then hydrogen or carbon.

00:43 And we can find this because this carbon is directly attached to a carbon in both cases, which is attached to two hydrogens and one carbon, and we will compare these carbons.

00:57 This carbon is attached to three hydrogens, and one of the tops attached to two hydrogens and a chlorine.

01:02 So chlorine is a higher atomic number than the hydrogen, so that will have the highest priority.

01:06 Since our highest priority groups are on the same side of the double bond, this will be said configuration.

01:12 For part b, the group of the highest priority is this group down here, since we have a double bond involved, and double bonds have a higher priority.

01:24 And the carbon that is directly attached to is attached to two hydrogens and a carbon instead of three hydrogens like this one.

01:31 So it has higher priority.

01:32 The carbon on the right, it's groups.

01:36 We have a carbon bonded to one hydrogen and two carbon or two ch3 groups.

01:44 Group on the bottom, we have a carbon bonded to two hydrogens in carbon.

01:48 So the group that on the top will have the highest priority since it's only bonded to one hydrogen and two carbons.

01:55 The carbon has a higher priority than hydrogen since it has a higher atomic number.

01:59 So for part b, since the highest priority, party groups are on opposite sides of the double bond.

02:06 It has an e -configuration...

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