[mass]

How many double bond equivalents are there in each of the following molecules?
C6H1206. Whats the method so I can do the rest of the questions by myself.

[Astrokel]

How many double bond equivalents are there in each of the following molecules?
C6H1206. Whats the method so I can do the rest of the questions by myself.

You should recognize C6H1206 is glucose.

http://campus.northpark.edu/biology/cell/carbohydrates.html

Hope this helps

Kelvin 

[sjb]

GIYF, try http://www.google.com/search?q=double+bond+equivalents

C₆H₁₂O₆ is not always glucose, mind.

It could be any of Allose, Altrose, Glucose, Mannose, Gulose, Idose, Galactose, Talose, Psicose, Fructose, Sorbose, Tagatose (and that's just the straight chain hexoses) - the principle is the same though.

[mass]

can one of you take me through the method rather than just point me towards google. Thanks.

[sjb]

OK, on the first page of google (from where I'm sitting), I see

http://en.wikipedia.org/w/index.php?title=Degree_of_unsaturation

It says

The formula for degree of unsaturation is

 
where C is the numbers of carbon atoms, H is the numbers of hydrogen atoms, X is the numbers of halide atoms, and N is the numbers of nitrogen atoms. Do not count group VI elements such as oxygen and sulfur atoms (but count H groups attached to oxygen atoms, such as hydroxyl groups). Halogen atoms (F, Cl, Br, I) count as H atoms for degree of unsaturation calculations.

Let's apply that to Pencillin G. This has the formula C₁₆H₁₈N₂O₄S.

Doing the calculation, you can see that there are (2x16 + 2 - 18 + 2)/2 or 9 degrees of unsaturation (or double bond equivalents) in the molecule.

Looking at the actual structural formula, , you can see the benzyl ring (making 4) the amides (an further 2), the carboxylic acid (1) and the 5:4 fused rings (an extra 2), total 9 as predicted by the DBE formula.

Can you now have a go at your formula?