biology/chemistry question?

Question

ok so for rings and chains of things like glucose, sucrose, fructose, etc. , i dont get how you take it from the chain and put it into the ring...im soooo confused. like
h
I
h- c- oh
I
h- c=O
I
ho-c-h
I
h- c- oh
I
h- c- oh
I
h- c-oh
I
h
HOW DO I GET THIS INTO A RING? dont just show me the ring, actually give me dummy steps to do it. keep in mind im only a freshman haha
ps. the lines separating each scarbon is sopossed to be centered under the "c" i tried to but the computer wont let me

just how to get it into a ring

Answer 1

Are you wanting to know what kind of ring?

The compound you drew above is D-Fructose. It has a very specific 5 member ring structure, called alpha-D-fructofuranose. I do not know of any "general rule." In fact D-Fructose can form a 6 member ring as well.

Other compounds that are similar, such as D-Glucose or D-Galactose, form 6 member rings. Glucose, for example can make both an alpha (below the ring) and beta (above the ring) form of the Glucopyranose. In nature, it is almost always the beta form.

Sucrose has two rings, one for each sugar in it (glucose and fructose).

If you are serious about studying biology and biochemistry, the best thing you can do is just memorize the ring structure of the very most common sugars. There is no short-cut.

See the sites below for help:

Answer 2

Ok, the carbon double bonded to the oxygen I will call C1 (you have an extra H on there), and number downward from there. So the bottom carbon is C5. As you'll learn in organic chem, atoms with free pairs of electrons can bond to carbons with double bonds by eliminating the double bond. So what happens is that the Oxygen atom attached to C5 attacks C1. The oxygen on C1 takes back 1 shared pair of electrons leaving it with a negative charge and the oxygen on C5 gives up the hydrogen that it was attached to. The Oxygen that was originally attached to C1 picks up the proton to become an -OH group and the transformation is complete! I believe the odds of getting the alpha or beta isomer are 50/50. Just be sure to rotate between the equatorial as axial positions correctly, depending on what form you have.

If you look through some organic chem text, you will probably see a good diagram with arrows to show electron movement.