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Chair and Boat Shapes for Cyclohexane. Created by Sal Khan.
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For all the cyclic molecules we've dealt with so far.
We've just drawn them as rings.
For example, for cyclohexane.
We've literally just drawn it as a hexagon.
We've drawn cyclohexane like that.
We know from the last several videos that all the bonds for carbon don't sit in the same plane.
We take the example of methane, that's.
The simplest example.
You have your carbon sitting in the middle.
You'll have kind of a hydrogen popping out like that.
Another hydrogen that's in the plane of the screen.
Another one that's behind the screen, and another one that is straight up.
You kind of have this tetrahedral structure.
And in the case of methane, you have that 109.5 degree bond, angles.
Carbon likes to form bonds of this shape.
It won't always be 109.5, degrees.
It'll, be something close to it, depending on what the different atoms or molecules are that.
It is bonded to.
So given that.
What would a cyclohexane molecule? Actually look like if we try to visualize it in three dimensions? So to think about that, let's think about these two bonds, first.
I'll, try my best to draw it in one of its three-dimensional shapes.
Those bonds right there.
I will draw like that.
Then this down here, in orange, I will draw like this.
Then this up here, in magenta, I will draw like that., And then.
Let me see, in, in purple, I'll.
Do these two right over here, and I'll, draw them like this.
You have that and like that.
This, hopefully makes clear that over there is that end over there.
This end over here is this end over here.
And this way that I've drawn the cyclohexane is called a chair.
Configuration., Chair, shape.
It might be obvious.
It looks like a chair.
The back of the chair.
This is where you would sit down on the chair, and I.
Guess? The back of your calves would go against here.
Your, knees would sit on it someplace like that.
That's called the chair.
Another configuration that it could be in is called the boat.
So if I were to put this exact one in the boat configuration, if I take it from a slightly different perspective, if I'm looking at it, kind of, head on, it would look something like this in the boat.
It would look like this., Now I want to use the purple.
It would look like that.
The first thing you're probably saying, is, Sal, you said that the reason why it looks like this is because carbon likes to form these kind of tetrahedral, or this tripod shaped bonds., I don't, see the tripod shaped bonds either here or here.
Let me, draw that boat a little bit.
At least this end of the boat a little bit better.
You say, well, I don't, see that tripod shape over there.
And to see the tripod shape.
You just have to draw the hydrogens.
Let me draw some hydrogens here.
Let me draw a hydrogen here that will go straight down like this., A, hydrogen that goes straight down over here.
A hydrogen that goes straight up over here, straight up over here, straight down over here, straight up.
I've now, drawn one hydrogen on every carbon.
Now, let me draw some hydrogens.
Let me, draw a hydrogen here that goes straight up, not up really-- to the side over here.
So, a hydrogen there.
Let me draw a hydrogen over here.
That does the same thing.
Those guys have their hydrogens.
Hydrogen, right over here., And, then, let's, see.
This guy needs his hydrogens still.
So he'll have a hydrogen that goes down like that, and a hydrogen.
And it goes like that.
This guy will have a hydrogen that goes like that.
When you see it like this, if you look at any one carbon on this molecule, if you look at any one carbon, you can see that's forming the same tetrahedral shape that has a tripod at every one.
You have that close to, roughly 109 degree, 110 degree angle between each of the constituents that are bonding to the carbon.
Now, I've drawn, the different hydrogens that are coming off of these carbons in different colors, and I've done it for a purpose.
The ones that are going straight up or straight down.
We call those axial hydrogens.
And, the ones I drew in orange that are kind of going to the side in some level.
We call these equatorial.
These are equatorial hydrogens.
The reason why it's useful to know that name is when we talk about the different configurations, the different chair and boats, whether something is equatorial or axial can change if this were to flip up, or vice versa, and things like that., And, we'll, talk more about that in the next video.
The reason why they're called equatorial is if you think about it, and it's sometimes hard to visualize, this bond, right here is parallel to this bond right over there.
This bond right over here is parallel to that.
The equatorial bonds are parallel, to some part of the ring.
So that one is parallel to that right over there.
Actually I should even, I could even color-code that., This, well, I, don't want to use that same color.
This is parallel to this.
And this is parallel to that.
We could do it for all the equatorial bonds.
So for example, I don't, want to-- I'm running out of colors, here.
This right here is parallel to this, and this, and that over there.
We could keep doing it for all of them.
I could do it for the other set right? Here.
This guy, right here is parallel to that guy over there.
I, didn't, quite draw.
It like that.
But hopefully it makes the idea clear.
And, I'll do one more of these just to show what's parallel to what.
This bond is parallel to that.
The ones that are parallel to some part of the ring we're, calling equatorial.
And, the ones that kind of jump out of the ring, that aren't parallel to any other part of the ring, we're calling those axial.
And, the way I've drawn.
The axials are the ones that point up and point straight up and point straight down.
We can do the same thing on a boat configuration.
One question, you might ask is, well, there's, these two configurations.
Both of these would result in tetrahedral type shapes at each of the carbons.
Let me draw it for you.
This axial hydrogen is pointing straight down.
This one is pointing straight down.
This hydrogen is actually going to point straight down because we flipped it up.
And then over here, you would have a hydrogen point, straight up.
And then one that's kind of pointing down.
This gives a tripod there.
To have the tripod over here, you'll have to have a hydrogen that points a little bit like that, one that's pointing a little bit like that, along, well.
You can kind of view it along the same plane as this guy would be parallel.
It's hard to see it in this.
But he would actually parallel to that.
This guy would be out like this.
And then this guy would have an axial hydrogen.
And then he would have one equatorial one just like that.
You could draw the tripod shapes in either the chair or boat configuration.
One question, is, well, what's, more stable?, That's, actually, one of the main points of being able to visually think about the three dimensional structure of any of these hydrocarbons, or in this case, cyclohexane.
So in this situation, we know from past videos, that all of these carbons with their hydrogens around them.
These bonds, these have electron clouds around them.
The electron clouds are negative.
And so they want to get as far away from each other as possible.
This chair configuration, you have this carbon up here.
The ch2 we could consider it, has two hydrogens and is connected to the rest of the ring.
It's as far as possible from this ch2 as possible.
So in that situation.
We have a lower potential energy, or it is a more stable.
Shape., Or, more stable, configuration.
In, the boat configuration.
This ch2 up here is much closer to this ch2, I, mean, that's, really the main difference between the two.
They want to get away from each other.
They want to repel ech, other.
This one will have higher potential energy, or it will be less stable.
This is just a starting point of how to visualize cyclic hydrocarbons and we'll use this information in the next video to think a little bit more about, maybe, the different chair configurations that a molecule could have, and what could be more stable.
This situation, in the case of just cyclohexane, the two chair configurations are equally stable.
Let me just touch on that a second.
You have, well, I, don't have to-- actually.
Let me see.
I, won't copy and paste.
I'll just redraw.
The other chair configuration for this guy.
Let me just do it separately over here because I've made the colors here.
Let me, draw two, the same cyclohexane.
But in two different chair configurations that it could be equilibrium in.
You could have this one.
You could have this one.
So this could be one chair, configuration, and I'll draw it like this.
Then the same hydrocarbon could be in-- or the same cyclohexane could be in equilibrium with the this other chair configuration that looks like this.
Let me have a little more space.
It looks like this.
Let me do the pink.
It goes up like that, like that., Let me, make sure I'm-- no, I want to do it.
Pink guy goes like this.
Then the blue guy is going to be just like this.
So notice, in this situation, this carbon appears kind of at the top of the chair, and this carbon is at the bottom.
And then they've flipped.
These are equally stable.
One way to think about is all of the axial guys on this carbon here turned into equatorial on this carbon and vice versa on the two.
Let me show it to you.
Let me just draw the hydrogens on this carbon.
This carbon's, hydrogens has an axial hydrogen, and has an equatorial hydrogen, whose bond would be parallel to that just like that.
This guy would have an equatorial hydrogen whose bond is parallel to actually both of these guys.
And, an axial hydrogen.
But when it flips, and I'm just drawing those guys' hydrogens.
But when this structure flips like that, what happens? Well, this hydrogen over here goes into this position.
And this yellow hydrogen over here goes into this position.
So over here.
It was equatorial.
And now it becomes axial.
Same argument can be made over here.
This equatorial hydrogen.
When it flips-- when this whole blue part flips down-- now becomes axial.
This axial hydrogen, when you flip, it down, becomes equatorial.
You can actually do that for all of the hydrogens.
Over here you have an axial hydrogen.
You flip it.
You have an axial hydrogen.
And then you have an equatorial hydrogen.
You flip it.
These two equatorial hydrogens become axial.
They become axial.
And then both of these guys become equatorial.
Let me do that in yellow.
Both, this guy, and this guy become equatorial So this.
And that become equatorial.
They become parallel to the other end.
You could do it for these two hydrogens, as well.
Another interesting to think about.
This is really just practice on visualizing what's going on.
When we when we visualize--.
The Boat Conformation of cyclohexane is created when two carbon atoms on opposite sides of the six-membered ring are both lifted up out of the plane of the ring creating a shape which slightly resembles a boat. The boat conformation is less stable than the chair form for two major reasons.What shapes does cyclohexane have? ›
Conformations of cyclohexane
A regular hexagon shape contains internal angles of 120o. However, the carbon-carbon bonds belonging to the cyclohexane ring have a tetrahedral symmetry, with the bond angles corresponding to 109.5o.
The most stable conformation of cyclohexane is called the “chair“ conformation, since it somewhat resembles a chair. In the chair conformation of cyclohexane, all the carbons are at 109.5º bond angles, so no angle strain applies.What is the structure of a boat? ›
The hull is the main, and in some cases only, structural component of a boat. It provides both capacity and buoyancy. The keel is a boat's "backbone", a lengthwise structural member to which the perpendicular frames are fixed. On some boats a deck covers the hull, in part or whole.What is the structure of a boat called? ›
The body of a boat is called its hull . At the upper edges of the boat's hull are the gunwales . The gunwales provide extra rigidity for the hull. The cross-section of the stern, where you attach an outboard motor, is called the transom. On the top of the boat are metal fittings called cleats.What are the shapes of Cycloalkanes? ›
Cycloalkanes are alkanes that are in the form of a ring; hence, the prefix cyclo-. Stable cycloalkanes cannot be formed with carbon chains of just any length.What is chair and boat conformation? ›
The terms chair conformation and boat conformation apply mainly to cyclohexane. The key difference between chair and boat conformation is that a chair conformation has low energy, whereas a boat conformation has high energy. Therefore, the chair conformation is more stable than boat conformation at room temperature.Why does cyclohexane adopt a chair conformation? ›
Although there are multiple ways to draw cyclohexane, the most stable and major conformer is the chair because is has a lower activation barrier from the energy diagram.What is chair conformation of cyclohexene? ›
In the chair conformation of cyclohexane, all the carbons are at 109.5º bond angles, so no angle strain applies. The hydrogens on adjacent carbons are also arranged in a perfect staggered conformation that makes the ring free of torsional strain as well.What is the most stable chair conformation of cyclohexane? ›
The most stable conformation of cyclohexane is the chair form shown to the right. The C-C-C bonds are very close to 109.5o, so it is almost free of angle strain. It is also a fully staggered conformation and so is free of torsional strain.
Cyclohexene has two sp2 hybridised carbons in the six-membered ring. The predominant conformer of the cyclohexene is half-chair. The half-chair conformation has a C2 axis present and belongs to C2 point group. The chiral half-chair conformation has two enantiomeric isomers associated with it.Why is boat conformation less stable? ›
Boat form of cyclohexane is less stable than chair form due to an interaction of flag pole H creates steric strain at top of carbon.Which chair conformation of cyclohexane is the least stable? ›
Half chair conformer is least stable due to maximum strain.Why is the chair conformation more stable than boat? ›
For many cyclohexanes, the chair conformation gives the molecule a lower total energy, and thus more stable spatial arrangement than the boat conformation because steric hindrance is minimized, particularly for the 1,4 nonbonding hydrogen or substituent interactions.What shape is best for a boat? ›
"V-shaped" hulls are planing hulls, and are the most common type of hull for powerboats. Deep v-shaped boats are designed to plane on top of the water at higher speeds and provide a smoother ride through choppy water.What is the shape of the boat and why? ›
Hence The shape of boats and ships is streamlined. to reduce friction due to air.What shapes are used in a boat? ›
Different Types of Boat Hulls:
Flat Bottom Hulls: a hull that has almost no deadrise. Deep-V Hulls: a wedge-shaped hull from bow to stern. Modified-V Hulls: the most common hull for small boats.
When looking forward, toward the bow of a ship, port and starboard refer to the left and right sides, respectively.What are boat dimensions called? ›
Important words in this category are: Beam – The width of the widest point of the boat. Beam on the centerline (BOC) – The beam measurement as used for multihull vessels. Draft – The distance between the keel of the boat and the waterline; indicates the minimum depth of water the vessel needs to float.What is the shape around each carbon in cyclohexane? ›
Answer and Explanation: The given compound is cyclohexane . hybridization and possess a tetrahedral geometry. As in the given structure for cyclohexane, each carbon atom is bonded to carbon and hydrogen atoms through 4 single covalent bonds; therefore, the geometry of the carbons is cyclohexane is a tetrahedral.
There are two ways to draw cyclohexane because it can be in a hexagon shape or in a different conformational form called the chair conformation and the boat conformation.Are cycloalkanes tetrahedral? ›
Just as in the straight–chain alkanes, the four orbitals around each carbon atom in the cycloalkanes are arranged tetrahedrally.What are the two types of chair conformation? ›
Axial and Equatorial Bonds
Apart from these are two types of bonds we use in chair conformations: axial and equatorial.
You can see the chair conformation of cyclohexane in the image to the right. In this type of conformation, there are two positions: axial and equatorial. Axial positions which perpendicular to the plane of the ring – these are highlighted in red on the diagram. The angles of these bonds are usually around 90˚.How many chair conformations does cyclohexane have? ›
Since there are two equivalent chair conformations of cyclohexane in rapid equilibrium, all twelve hydrogens have 50% equatorial and 50% axial character.What are the four conformations of cyclohexane? ›
- Half Chair Form ( Ring Strain=108 kcal/mol)
- Boat Form ( Ring Strain=7.0 kcal/mol)
- Twist Boat ( Ring Strain=5.5 kcal/mol)
- Chair Form( Ring Strain=0 kcal/mol)
Answer: Chair conformation of cyclohexane is more stable than boat form because in chair conformaion the C-H bonds are equally axial and equatorial, i.e., out of twelve C-H bonds, six are axial and six are equatorial and each carbon has one axial and one equatorial C-H bond.How many types of conformation are possible in cyclohexane? ›
Cyclohexane can form three different conformations.What are the stable conformations of cyclohexane? ›
Chair form is the most stable conformer of cyclohexane.What is the order of stable conformation of cyclohexane? ›
Chair > twist boat > boat > half chair.
A third conformation is produced by twisting the boat to give the twist or skew-boat conformation. The twist relieves some of the torsional strain of the boat and moves the flagpole H further apart reducing the steric strain. Consequently the twist boat is slightly more stable than the boat.What is the structure of cyclohexane molecule? ›
Cyclohexane (C6H12) is a cyclic compound in which six carbons are covalently bonded in a ring structure. Because of this ring structure, each carbon is bound to two hydrogen and to two adjacent carbons, as seen in the Lewis structure below.What is the point group of boat form of cyclohexane? ›
Hence, the point group of boat conformation of cyclohexane is C 2 v .Why is the boat conformation of cyclohexane less stable? ›
Boat form of cyclohexane is less stable than chair form due to an interaction of flag pole H creates steric strain at top of carbon.Is boat conformation the most stable conformation of cyclohexane? ›
The chair conformation is the most stable conformation of cyclohexane. A second, much less stable conformer is the boat conformation. This too is almost free of angle strain, but in contrast has torsional strain associated with eclipsed bonds at the four of the C atoms that form the side of the boat.How do you draw the structure of cyclohexane? ›
The easiest way using which we can draw the structure of cyclohexane is by simply drawing a hexagon. And in the hexagon each point depicts a fully saturated carbon atom with hydrogen atoms. When cyclohexane is depicted using a hexagon each carbon atom and each hydrogen atom in the structure appears the same.What is the simple structure of cyclohexane? ›
Cyclohexane has the chemical formula of C6H12. It forms a ring, so there are no CH3 ends, instead each carbon is attached to a CH2. The simplest way to draw cyclohexane is simply draw a hexagon. According to this format, each point depicts a fully saturated (with hydrogen atoms) carbon.What is the structure and uses of cyclohexane? ›
Cyclohexane is used as a solvent, oil extractant, paint and varnish remover, and in solid fuels.How will you justify the chair form of cyclohexane is more stable than the boat form? ›
The chair conformation drawing is more favored than the boat because of the energy, the steric hindrance, and a new strain called the transannular strain. The boat conformation is not the favored conformation because it is less stable and has a steric repulsion between the two H's, shown with the pink curve.Why is the chair conformation of cyclohexane more stable than boat conformation? ›
Answer: Chair conformation of cyclohexane is more stable than boat form because in chair conformaion the C-H bonds are equally axial and equatorial, i.e., out of twelve C-H bonds, six are axial and six are equatorial and each carbon has one axial and one equatorial C-H bond.
In the chair conformation of cyclohexane, all the carbons are at 109.5º bond angles, so no angle strain applies. The hydrogens on adjacent carbons are also arranged in a perfect staggered conformation that makes the ring free of torsional strain as well.Why is chair more stable than boat conformation? ›
For many cyclohexanes, the chair conformation gives the molecule a lower total energy, and thus more stable spatial arrangement than the boat conformation because steric hindrance is minimized, particularly for the 1,4 nonbonding hydrogen or substituent interactions.Why is boat less stable than chair? ›
The boat conformation suffers from torsional strain, making it less stable (higher in energy) than the chair. Steric strain in the boat arises mainly from the repulsion (steric crowding) between the two hydrogens on the ends of the "boat.Why is twist boat cyclohexane more stable than boat form? ›
The twist relieves some of the torsional strain of the boat and moves the flagpole H further apart reducing the steric strain. Consequently the twist boat is slightly more stable than the boat.Why is boat conformation stable? ›
Boat conformation has steric hindrance on their carbon 1 and Carbon 4 between two equatorial hydrogen which gives them the high torsional stress and their $ C - C $ bond are also ellipse making them less stable than the chair conformers.