This is a discussion on Henryv's Technical Info Thread within the Prohormones and Designer Steroids forums, part of the Performance Enhancement category; Here I'll explain some technical stuff about steroids; how to understand steroidal nomenclature and structural diagrams, that sort of thing. ...
Reputation: 19957 Array Here I'll explain some technical stuff about steroids; how to understand steroidal nomenclature and structural diagrams, that sort of thing. If you're not into it, move along. If you are, follow along and ask questions where necessary.
This is not a Q&A thread. It's not a misc thread. Please keep it on topic and uncluttered.
Reputation: 19957 Array It's impossible to teach this stuff without understanding a little about carbon; it's the basis of the steroid structure. I promise I'll keep it as simple as possible.
Rule one: each carbon atom is capable of bonding with four other atoms. These are called "covalent bonds". You don't need to know right now what those bonds are made of, or anything like that.
^ All three of the above diagrams are of propane. Keep looking at them until you understand that they're different ways of drawing the same thing: three carbon atoms, bound to a bunch of hydrogen atoms. If they're not drawn, we assume the hydrogen bonds are there but not shown.
Reputation: 19957 Array Lets get straight into the nitty-gritty.
^ All steroids look pretty much like this, with bits on. You start off with three hexagons and a pentagon, and add functional groups, and double bonds, and you have bunch of wonderful steroids.
Each number represents a carbon atom. Each line represents the bond that atom has with its neighbour. So each "corner" is a carbon atom. While the numbering system looks a bit confusing, it counts around the steroid (in a roundabout way). The most important positions are 3, 4, and 17. If you can remember where they are for now it will come in handy later on.
We could draw little C's to show where all the carbon atoms are, but it would be a real pain since there's 19 of them, and loads more hydrogens. Much easier to assume anything not labelled is carbon (with hydrogen attached anywhere not shown).
Last edited by henryv; 10-31-2011 at 08:11 PM.
Reputation: 19957 Array
As I mentioned, steroids are made of four carbon rings. Three (joined) hexagons and a pentagon. Each of these rings is designated a letter; A - D.
So far we've only dealt with the steroid numbering protocol. This is fairly fundamental to understanding nomenclature, since when you describe a steroid scientifically like that you have to say where exactly the functional groups and double bonds are in a way everyone can agree on. I'll post the numbers again:
Reputation: 19957 Array Now I'm sure you've heard that some steroids are "17a-methyls", or seen the nomenclature list "17b-hydroxy" as part of the formula. You've probably figured out that the 17 part refers to the 17th carbon of the steroid "skeleton", the one labelled 17 on the image above. Methyl and hydroxyl are two types of functional groups, or attachments, that can change the effects of a compound. But what do the "a" and "b" bits mean?
To understand the answer to this, we need to understand that steroids are not flat, like the paper we draw them on. As we've already seen, structural drawings are simplified representations that let us communicate the concept of the molecule to each other. If we were to draw the steroid testosterone in 3 dimensions it would look something like this:
Note that the top side of the picture is labelled β (beta), and the bottom side is labelled α (alpha). When something is flat with the plane of the steroid (planar), it does not need to be designated alpha or beta (a or b), but if it's sticking up or down, then when we describe it we need to know which.
Now back to the easy way of looking at it:
See how the lines attached to the Hs and the OH start off thin where it joins the steroid skeleton, and ends up thick? That is to show that those things aren't planar (flat), they are coming off the page either up or down. The dotted lines (see 9 and 14) are going down to the bottom side of the steroid. This is the alpha side. The solid lines are coming up towards you, on the beta side.
Lets take a closer look at that top right-hand corner.
OH is the symbol for a hydroxyl group. This one is attached on the beta side at carbon 17. Therefore this can be described as a 17b-hydroxyl.
- This group is common to all active anabolic steroids. Without it a steroid cannot bind to the androgen receptor.
Some images adapted from ergogenics.org
Cheat Notes
The dotted lines are always going down to the bottom side of the steroid. This is the alpha side.
The solid lines are coming up towards you, on the beta side.
Dotted = a
Solid = b
One way I remember it is to think of "above" and "below" - and I know that I need to reverse them, so a is below and b is above.
Reputation: 19957 Array Almost all of the anabolic compounds taken by steroid users are androgens. That means that they are based on the androstane structure.
This is the androstane structure. It is a basic steroid structure with few functional groups. It has 19 carbon atoms (we have already seen the numbering system). Two of these carbons are in the form of methyl groups as we've already discussed (the two black lines coming from the top of the structure).
Do not be distracted by the wiggly line attaching the H (hydrogen) at C5. This wiggly line indicates that the hydrogen can either be attached at the alpha position (which would be indicated with a dashed line) or the beta position (which would be indicated with a solid line). When we say simply "androstane" it could be either, and that's what the wiggly line shows.
This is the estrane structure. All estrogens are based on this carbon skeleton. Note that it is identical to the androstane structure in all but one respect; it is missing the 19th carbon, the methyl group attached to C10. It has in it's place a hydrogen atom. It is for this reason that when describing steroids based on this structure we can either say "estra" or "19-norandro" (meaning an androgen without the 19th carbon).
- Hidden away in the nomenclature for almost all the steroids you encounter will be the terms "andro" or "estra" (or "19-norandro"). All of the rest of the nomenclature describes how the steroid differs from the basic steroid structure seen above.
Reputation: 19957 Array So far all the carbon to carbon bonds we've looked at have only been single bonds (the carbon atoms share one pair of electrons). Carbon atoms are also capable of forming double bonds with each other (where they share two pairs of electrons), and indeed these are very common in steroids, so we'd better learn a bit about them.
- Carbon compounds with only single bonds are called alkanes.
- Carbon compounds with at least one double bond are called alkenes.
This difference is important, because it affects the way the nomenclature of a given steroid is written.
- An androstane is an androgen with no carbon to carbon double bonds.
- An androstene is an androgen with at least one carbon to carbon double bond.
- An estrane is an estrogen with no carbon to carbon double bonds.
- An estrene is an estrogen with at least one carbon to carbon double bond.
There is another class of steroids called gonanes. You don't need to know much about them since there aren't many anabolics on the market based on this skeleton (the only one on the PH market that I'm aware of is 13-ethyl/M-LMG). The only reason I mention them is because if a steroid of this class has a double bond it is then called a gonene. There is also another class called pregnane, which is a pregnene if it has a double bond.
Double bonds are really easy to spot on the structural diagrams.
They are represented by a double line, like = whereas single bonds are represented with a single line like -.
Lets take a look at testosterone. I have circled the C-4,5 double bond of testosterone for you in red (the double bond that joins carbons #4 and carbons#5).
- In a structural drawing, a pair of parallel lines always denotes a double bond.
- In steroidal nomenclature, a carbon to carbon double bond is always indicated by ene or en.
The image above is testosterone. Testosterone can be written as androst-4-en-17b-ol-3-one or 4-androstene-17b-ol-3-one.
The androst part indicates the androstane skeleton. The 4 part indicates where the double bond starts from (it is always assumed to go to the next carbon up in number order, unless indicated otherwise). The ene part tells you that the number 4 is telling you where a double bond is.
Reputation: 19957 Array
This is the steroid lettering and numbering system.
This is the androstane structure.
- Note the C-19 methyl group.
This is the estrane structure.
- Note the lack of a C-19 methyl group (instead it has a hydrogen atom in it's place, denoted by the H symbol).
Neither androstanes nor estranes have any carbon-to-carbon double bonds. If they did, they would be androstenes and estrenes. Refer to the previous post on the subject for an explanation.
This is methyl 1-test. I have circled the double bond in red for you.
Note that it has a C-19 methyl group (sometimes these are labelled with CH3, their chemical formula) and a double bond, so it is an androstene.
Reputation: 19957 Array When we use a number in steroidal nomenclature, it always refers to the steroid numbering chart in the post above. So, when we want to discuss quantity, we have to use a different term.
Like many of the terms used in chemistry, the prefixes used originate in ancient Greece (even the word chemistry comes from the Greek word khymeia).
- mono
- di
- tri
- tetra
- penta
- hex
And so on.
We've already learned that a double bond is referred to by the term -ene
- If there's two double bonds, it's referred to as a diene
- If there's three double bonds, it's referred to as a triene
- If there's four double bonds, it's referred to as a tetraene
So it goes.
This is the structure of dianabol.
- It is probably the most famous diene - in fact that's where it's name comes from. I trust that you can see the two double bonds in the A ring.
This is the structure of the aromatase inhibitor ATD.
- ATD is short for androst-1,4,6-triene-3,17-dione, and by now I'm sure you can see the three double bonds from which it gets the "triene" part of it's name.
Reputation: 19957 Array Functional groups are groups of atoms attached to the sterane structure that affect the way the steroid will be metabolised and utilised by the body.
We have already mentioned the methyl group. This is a carbon atom with three hydrogen atoms attached. We know that carbon can join to four other atoms - the fourth bond is the one holding it in place on the steroid.
We know that the two black lines sticking out of the "top" of the steroid are methyl groups attached at C10 and C13. The two carbon atoms that form the methyl groups are carbons C19 and C18 (see below).
Methyl groups may also be explicitly denoted by the formula CH3, as in the image below.
CH3 means one carbon atom, bound to three hydrogen atoms (once again, there's no need to actually show the hydrogens, we know they're there).
- Because the C19 and C18 methyl groups are common to all androgens, we don't need to list them when we describe the nomenclature of the compound. We can say "androgen" and it is assumed that those methyl groups are there. If the C19 methyl group is not there, we can call it a "19-nor-androgen".
- Nor- is a prefix that means a carbon (and accompanying hydrogens) has been removed.
We will discuss the reason for adding a methyl group (typically at C17) at a later stage. Currently we're just trying to recognise them on the diagrams and in the nomenclature.
- You will see it in the nomenclature as "methyl" (or "dimethyl" if there's two of them, trimethyl if there's three of them), preceded by the carbon number where they're attached to the steroid. The most commonly seen examples will be 17a-methyl and 2a,17a-dimethyl.
Reputation: 19957 Array
This is a structural drawing of testosterone.
This is the same drawing, but I have numbered the carbon atoms 1 - 4 (per the steroid numbering post early on). I have also circled in red an oxygen atom that is double-bonded to the carbon number 3 (the oxygen atom is labelled "O", and the double bonds should be clear to you from our previous posts on single and double bonds).
Hopefully you recall that a carbon atom is capable of forming four bonds with other atoms. This gives it a "valence" of 4. Oxygen on the other hand has a valence of 2 - so it can only bond to two other things. In this example, oxygen is sharing BOTH of it's bonds with the same carbon atom (carbon #3) - hence the double bond. Please note that since this double-bond is not carbon-to-carbon, it's not an alkene.
This functional group is correctly called a carbonyl group, however the term is so rarely used that that is the first and only time we will refer to it. The term we will use for this group is a ketone, though this more correctly refers to the compound itself rather than the functional group.
- Just like the term alkene (for a double bond) is contracted to "-ene" when we write it in the nomenclature of a compound (and "-diene" when there's two of them), so ketone is abbreviated to "-one" (and "-dione" when there's two, and -trione when there's three).
So in the example picture above, the circled element is written as "3-one", since the oxygen function is attached to the third carbon atom.
Reputation: 19957 Array
Here we have again the testosterone structural formula, though this time I have circled an oxygen atom attached to the 17th carbon by a single bond. The oxygen atom's remaining bond is attached to a hydrogen atom. We can see from what we have learned already that the OH (oxygen-hydrogen) group is attached in the beta position.
- This "OH" group is called a hydroxyl since it's made from hydrogen and oxygen.
- When this hydroxyl group is attached to a carbon atom, the resulting compound is called an alcohol.
- Just like the ketone is abbreviated to "-one", and the alkene to "-ene", an alcohol is abbreviated to "-ol", and if a compound has two hydroxyl groups, it is a "diol".
So using the example above, the functional group circled is written in scientific nomenclature as a "17b-ol".
Reputation: 19957 Array Now here's a quiz that will test just about everything we have covered so far.
Take a close look at the image below:
- Q1: Is this compound
a) an androstene
b) an estrene?
Here is the same compound, with some parts identified with coloured boxes:
- Q2: What functional group is circled in green?
a) methyl
b) ketone
c) hydroxyl
- Q3: This compound has two oxygen functions circled in red. This should be written as:
a) 3,17-dione
b) 3b,17b-diol
c) 3,17-diene
- Q4: Circled in blue is a:
a) ketone
b) double-bond
c) methyl
And for bonus points, correctly identify the steroid pictured.
Reputation: 924 Array This post is awesome. It wasn't too complicated but not too simple either. I feel smarter. Post answers to quiz? repped
Reputation: 19957 Array Thanks. It isn't finished yet, it will get more in-depth. Feel free to have a go at the quiz and post your answers.Originally Posted by mikevm
Reputation: 46832 Array
1 - a
2 - c
3 - c
4 - b
Reputation: 15411 Array 1. A
2. C
3. C
4. B
4-Hydroxy Testosterone ? but missing a Hydrogen in the 14b position?
Reputation: 19957 Array Good work. 3/4. Take another look at Q3.
1 - a
2 - c
3 - c
4 - b
It's actually 4-hydroxyandrostenedione, a.k.a. formestane, but you can have a bonus point for spotting my mistake.
I knocked up the diagram from a diagram of a 14-ene steroid I was discussing the other day and forgot to put the H back in.
Reputation: 15411 Array 3. Should have been A not C
I see where I got that wrong, to be 4-hydroxytestosterone it would have to be OH in the 4 AND 17 not O in 17... face palm... (this is one of the many reasons I am no chemist...)It's actually 4-hydroxyandrostenedione, a.k.a. formestane, but you can have a bonus point for spotting my mistake.
I knocked up the diagram from a diagram of a 14-ene steroid I was discussing the other day and forgot to put the H back in.
Reputation: 19957 Array All correct. Not many people understand this stuff at all, no need to facepalm.
Good job you two.
Reputation: 46832 Array I even cheated, I looked and looked for that one, couldn't figure out wtf it was, and I'm under the influence of intoxicating drugs from ear surgery yesterday.
Reputation: 19957 Array The left ear, the right ear, or the final front ear?
Reputation: 46832 Array 3rd ear blind
left
stapedectomy
been swimmy since Tuesday, head like a punchbowl ... much better today
Reputation: 19957 Array 
Reputation: 2984 Array In all honesty, organic really isn't that hard to understand at all. Learn your functional groups, regular bonding patterns of C, S, P, H, N, Al, Zn, Li, all alkali and halogens, Ca, Cu, O, and possibly a few others I missed. By that I mean: carbon normally makes 4 bonds, oxygen 2, nitrogen 3 (or four, as N+), etc. This is a lot easier than you think. After looking at enough compounds, you'll quickly begin to understand how many bonds each atom normally makes. UNDERSTAND DIFFERENT REPRESENTATIONS OF MOLECULAR STRUCTURES! This will make your life sooooo much easier. Know lewis structures, line diagrams, fischer projections, and your ring systems. Go over the IUPAC naming system as much as you can, but it's not really a priority. The names will come with practice. These are the things you need to know, the basics.
Once you get all that down, start learning about electron orbitals (and hybridization) and the LUMO HOMO stuff. Know the terms resonance, aromaticity, conjugation, and electronegativity. All of this deals with how bonds are made and what makes some compounds more "stable" then others. ALL BONDS DEAL WITH ELECTRONS!! When you start learning a thing called mechanisms, which I'll talk about in a bit, all you do is transfer electrons from one atom to another, making and breaking bonds. From this you will also learn the shape of s, p, d, and f orbitals and their hybrids. This tells you the bonding geometry (ex: CH4, or methane, has four sp3 orbitals that form bonds to the hydrogens in the shape of a tetrahedron.
The major, and most useful, part of orgo is understanding mechanisms that drive reactions. Once you get this, you should basically be able to create, at least in theory, any compound you ever could want.
Hope I covered enough to provide a good starting place for anyone interested to start their research. I'm also willing to make a thread discussing some of the basic components of chemistry if anyone is interested. Going back over the basics is always helpful. Plus, I love this subject and enjoy sharing and discussing the topic.
Other words you can look up on wiki if you're ever bored:
- thermodynamics
- molecular orbital theory
- aromatic compounds
- Organic mechanisms (should find a long list of all named reactions and their mechanisms)
- chirality
- isomers
- steriochemistry
- nucleophile and electrophile
- acid, bases, lewis acid, lewis base, pKa, Ka, pH, pOH
- equilibrium
- lechatliers principle (know the spelling is wrong)
- polar, protic, aprotic solvents
- kenetics
- transition state and activation energy
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