Priorities for Plane Drawings of Hexane
Drawing and Understanding Diagrams
The ability to draw and interpret the different diagrams that are used to stand for the different conformations is a very important skill to acquire. It will likely require that you maximise your artistic skills! The but person that will be decieved past your poor diagrams is yous! Your teacher(s) will be able to tell instantly that you are struggling, don't know or are trying to hide that you don't really know.
Nosotros need these diagrams because molecules typically have 3D shapes associated with them and we demand to exist able to accurately depict those 3D shapes on a 2d page (newspaper or screen). I due north many ways this is similar to the way nosotros wait at the plans for a house or a Lego kit where we use those plans to create that object exactly every bit intended. The different types of diagrams each have a specific feature that defines the fashion they demand to be fatigued and interpretted. This then allows for the unambiguous interpretation of those diagrams. Information technology is these features that are important to know and understand.
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Wedge-hash diagrams
Wedge-hash (or wedge-dash) diagrams are the most common representation used to show 3D shape every bit they are ideally suited to showing the construction of sp3 hybridised (tetrahedral atoms). They are rarely needed for sp2 (e.g. alkenes) or sp systems (east.g. alkynes).
Wedge-hash diagrams are usually drawn with ii bonds in the plane of the page, one infront of the plane, and 1 backside the plane. This gives the molecule 3D perspective: we envisage the bold lines being closer to u.s.a. and the hashes fading abroad in the groundwork.
When drawing wedge-hash it is a good idea to visualise the tetrahedral arrangement (or the appropriate geometry) of the groups and endeavour to make the diagram await like this. Information technology is worth looking at the cartoon and asking yourself does it make geometric sense ? Can you lot meet the shape you are trying to describe ? If the answer to that question is "no", then the diagram is inadequate and should be redrawn.
As a suggestion, they seem to be near constructive when the "like" pairs of bonds (two-in-aeroplane, 2-out-of-aeroplane) are next to each other, equally shown in the left box above.
Here are some other examples to review:
Remember that diagrams are being used to nowadays the required data efficiently. Organic chemists use line diagrams to represent structures every bit office of the symbolic code because they are quicker and easier to draw equally nosotros can just leave out the C atoms and the H attached to those C atoms because we know to just assume that they are in that location. This idea also carries over into wedge-hash diagrams. A mutual scenario is shown below where the bail to an H has been omitted and information technology is assumed that we know that it is in that location.
Sawhorse
Sawhorse diagrams are similar to wedge-dash diagrams, but without trying to apply "shading" to denote the perspective. The representation of propane shown beneath has been drawn so that we are looking at the molecule which is below us and to our left.
Newman Projections
Newman projections are drawn by looking directly along a particular bond in the arrangement (here a C-C bond) and arranging the substituents and then that they are as spaced around the atoms at each finish of that bail. The protocol requires that the atoms within the central bond are shown as a dot and circle as defined beneath. Think of them as an end on view of a particular bond and the showing the arrangement of the groups effectually that bail.
In club to draw a Newman projection from a wedge-dash diagram, it is useful to imagine putting your "eye" in line with the central bond in order to wait forth information technology.
Allow'south work through an example, consider drawing a Newman project by looking at the post-obit wedge-dash diagram of propane from the left mitt side.
- First draw the dot and circle to stand for the front end and back C respectively
- Since the front carbon atom has an H atom in the plane of the page pointing up nosotros can add that kickoff
- The back carbon atom has an H atom in the plane of the page pointing downwardly
- Now add the other bonds to each C then that it is symmetrical
- The groups / bonds ( blue ) that were forrad of the aeroplane of the page in the original wedge-dash diagram are now to our right
- Those behind ( light-green ) the plane are now to our left
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- Now you try the same thing, but looking from the right to generate the other Newman projection.
Fischer Projections
Fischer projections are msot commonly used to represent biomolecules such equally amino acids and carbohydrates (sugars) equally the provide a quick way of representing one or more multiple stereocenters. They tend to be less ordinarily used past organic chemists because they represent the molecules in an unfavourable conformation, i.eastward. an "unnatural position".
A Fischer projection is the view of a molecule oriented with the carbon chain oriented vertically and all the horizontal bonds oriented towards the observer (like arms coming out the hug you).
Note that Fischer projections of carbohydrates are typically drawn with the longest chain oriented vertically and with the more highly oxidised C (the carbonyl grouping) at the top. Here we meet the Fischer projections of the simplest carbohydrate, glyceraldehyde in its (Southward)-(-)- and (R)-(+)- forms:
S-(-)-glyceraldehyde
R-(+)-glyceraldehyde
Here is an example of a Fischer diagram with the stereochemistry at 2 centers. It'southward the aforementioned thought, carbon chain vertical and the horizontal bonds towards you. One way to "decode" a Fischer projection, is to draw in wedges and hashes to "reveal" the orientation of the bonds. This can assistance visualise the shape.
Drawing Cyclohexanes
Cartoon cyclohexane and so that information technology looks similar a chair tin can be the key to appreciating the difference between the axial and equatorial positions. If you lot are unable to draw good looking structures that clearly show axial and equatorial positions, so your teacher is probably going to assume that you don't know.
By not mastering the trick of drawing cyclohexanes the just person that actually suffers is yous the educatee. You deprive yourself of the knowledge and the take chances to appreciate it, what it means and most importantly what information technology tin tell you lot. Believe me, it will be needed later.
The first step is cartoon the chair itself. Although the chair "looks better" when slightly angled, it perchance easier to "acquire" to draw it with the center portion horizontal.
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Source: https://www.chem.ucalgary.ca/courses/350/Carey5th/Ch03/ch3-0-2.html
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