[lissydoll206]

Hi-

  I am working on a project and need to identify all of the funtional groups of Sildenafil Citrate (Viagra).  
  I am attaching a picture of what I have so far- I think I have all of them for the most part.  
  However, in the Sildenafil part, is there a Carbonyl group some where?  I was told that by someone, but I am having a hard time identifying it.  Also, are there only two amines present in the Sildenafil part? Or are the double bonded N's in the first two rings also considered to be amines?

Also, if you see any that I have missed, please let me know!

  Thanks for any help anyone can give me! It is greatly appreciated.

-Melissa

[lemonoman]

Looks good to me

Just one thing, "Slidefenil Citrate" - sounds to me like they might be bonded together somewhere?  Might want to check out out, since there's a crucial difference between two ions and a molecule.

[movies]

It's a salt.  There should be a positive charge in the sildenafil part.  Can you find it?  Then there should also be one carboxylic acid that is deprotonated to balance out the charge.

Soooo...what is the name for a deprotonated carboxylic acid?

Then, there is a name for the functional group with the C=N.  The two C=N functionalities will have different names.  Think about the name for other things that have a C=N.

Also I think that the name of the SO₂-N group is actually something different.  Close, but different.

[lissydoll206]

Alright, since it is a salt, there is a postive charge on the Sildenafil and a negative charge on the Citrate molecule.

  Is the positive charge on the Nitrogen that is a part of the bicyclo on the left hand side of sildenafil?  The one that has 4 bonds to it already.
   Then, the negative charge on the Citrate will come from taking off a hydrogen from one of the OH's on a Carboxylic Acid?

  Is the group that I labeled as Sulfoximines really Sulfate Esters instead?

  Also, is the C-N=C an imine?  I can't figure out the other N=... the one that is bonded to two other carbons... hmmm... hints?

  One more question... if given the IUPAC name: 1-[[3-(6,7-dihydro-1-methyl-7-oxo-3-propyl-1H-pyrazolo [4,3-d]pyrimidin-5-yl)-4-ethoxyphenyl]sulfonyl]-4-methylpiperazine citrate, where would you start on trying to number it to account for all the groups? I need to color code the parts of the structure with the different parts in the name.  

  Thanks again!

Melissa

[lissydoll206]

Ooops, forgot one more thing....

   Is the deprotonated carboxylic acid then an Ester?

Thanks!

[lissydoll206]

I have came up with a possible solution to what the C=N with two other Carbons attached to the N could be... is it from the functional group Azo?

Hmmm....

[Nucleophile]

ester is defined as molecule in which the carboxylic group is connected to a carbohydrate group on it's Oxygen end.

[movies]

Okay, I'll try to cover everything in one post.  Wish me luck.

1) You've identified where the charges are.  Good job!  Anytime that nitrogen has 4 bonds it should have a positive charge.

2) Nucleophile covered the definition of an ester.  Think about how the name changes when you take citric acid and deprotonate it to make the salt.  What is it called in the name here?  How could you apply the same naming convention to a generic carboxylic acid?

3) Sulfate esters are something different.  They are actually a higher oxidation state than you have here.  A sulfate ester would be something like dimethyl sulfate.  You got the correct name for the amide functionality, do you know how that changes when you have a SO₂ instead of a C=O?  Do you know the name for the reagent Ph-SO₂-Cl?

You identified that the C=N is an imine, so I think that a sulfoximine would be a C=N-SO₂-R funtionality.

4) So C=N is an imine, how do names change systematically when a charge is involved?  Are you familiar with Freidel-Crafts acylation reactions?  What is the intermediate charged species called in that reaction?  Another example, what is the salt product of mixing ammonia with HCl?

An azo group is usually an N=N functionality.

5) Finally, are you sure that IUPAC name is right?  Something seems fishy to me.