Tell whether each of the following compounds has the E or the Z configuration: a. b. c. d.

Name: Problem 35, Chapter 3: Organic Chemistry
Uploaded: 2021-07-19T22:31:12-08:00
Duration: 8 min 43 s
Channel: Allison Krajewski
Description: Tell whether each of the following compounds has the E or the Z configuration: a. b. c. d.

Tell whether each of the following compounds has the E or...

Key Concepts

Geometric Isomerism

Geometric isomerism refers to the existence of compounds with the same connectivity of atoms but different spatial arrangements due to restricted rotation. In double bonds, this phenomenon gives rise to isomers based on the different positions of substituents relative to the double bond's plane.

E/Z Configuration

The E/Z configuration is a system for categorizing alkenes based on the relative positions of the highest priority substituents attached to the double-bonded carbons. 'E' (from the German 'entgegen') indicates that the highest priority groups are on opposite sides, while 'Z' (from 'zusammen') indicates they are on the same side.

Cahn-Ingold-Prelog Priority Rules

The Cahn-Ingold-Prelog priority rules are a set of guidelines used to assign priorities to substituents attached to stereocenters or double bonds. This ranking is based on atomic numbers and connectivity, allowing chemists to determine which substituents govern the E/Z configuration in alkenes.

Transcript

00:01 Okay, so for each of these problems, you want to identify whether the structure has e or z nomenclature.

00:11 So the first thing you want to do is assign priority to each of these two substituents on the carbons of the double bond.

00:22 So one, assign priority.

00:28 And then step two, if you have your high priority is on the same side, then you would call it z.

00:40 If they're on opposite sides, you call it e.

00:46 So the way that i do this is, and the way that you should do this, is look at one carbon.

00:51 This is carbon one, and this is carbon two.

00:55 Well, it's not really, it's really carbon three and carbon four, but you get the idea.

01:05 So for carbon one, we have a methyl group and we have an etho group.

01:10 So if you go carbon by carbon, you want to look, it's kind of like alphabetical order.

01:16 So you want to look at your first atom on each of these.

01:19 So you have a carbon and you have a carbon.

01:22 So this carbon here is attached to three hydrogens, so three hydrogens, and it's attached to one carbon on this bond here.

01:31 This carbon here is attached to two hydrogens, and then it's also attached to two carbons.

01:38 So the carbon of the double one and the carbon of this methyl group.

01:44 So because going based on this, you have one carbon versus two carbon, your ethel group has a higher priority than your methyl group.

01:58 And then if we go on carbon two, again, let's go carbon by carbon.

02:03 So we have ch2.

02:06 So this carbon is attached to two carbons and two hydrogens.

02:11 This carbon is also attached to two carbons and two hydrogens.

02:15 So then we move on to the second carbon.

02:18 So this carbon is attached to one carbon and three hydrogens.

02:22 This carbon is attached to one carbon, two hydrogens, and one chlorine.

02:29 So of these, our chlorine has a higher priority than our carbon.

02:34 It's kind of like the most, not the least common denominator, the opposite of that, where you have whatever priority is your highest for each of these groups, you can compare them, meaning you want to compare your chlorine and your carbon.

02:56 So because chlorine has a higher priority, so now you have your higher priorities are both on the same side.

03:06 So because they're on the same side, that makes them z.

03:16 Let's go down to the second one.

03:18 So again, even since i'm calling them one and two, i'll call them a and b.

03:23 So on carbon a, you have, let's go atom by atom.

03:29 So on carbon a, you're attached to two carbons.

03:32 So this first carbon is attached to the one carbon, carbon a, and attached to these three hydrogen.

03:40 This carbon is attached to carbon a, and remember that a triple bond is the equivalent of saying this carbon is attached because this carbon and this carbon are in a triple bond, it's like saying this carbon is really bonded to three individual carbons.

03:57 So this carbon, we can say, is bonded to four carbons.

04:02 So because four carbons has a higher priority than one carbon, this is going to be our higher priority side.

04:13 On carbon b from the double bond, again, we want to go carbon by carbon.

04:20 So this carbon here, we're attached to two carbons and two hydrogens.

04:24 For this carbon here, this is an isopropal group...

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