 In the last module, we have discussed the formation of aminescetol and acetol formation of the aldehyde group with the addition of alcohol and similarly the formation of amiketol and ketol with the ketonic group and addition of alcohol. In this module, we will discuss the formation of ring structure of carbohydrates. For example, deglucose exists in a solution, not in the crystalline form. In a solution form, it has an intramolecular aminescetol in which a free hydroxyl group which is present at carbon atom number 5 reacts with the aldehyde group of the carbon atom number 1. In this structure or in this diagrammatic presentation, we will discuss the formation of aminescetol structure or in this diagrammatic presentation, we will see how the formation of a cyclic intramolecular structure is formed. This carbon atom number 1 which is aldehyde, it has C double bond O attached to it, so it is aldehyde group, it reacts with carbon atom number 5 which has OH attached on one side and hydrogen attached on the other side. So this is carbon atom number 1, it came here and carbon atom number 6 came here. This forms an intramolecular cyclization between carbon atom number 1 which contains this aldehyde group. And this reacts with OH, this OH carbon atom number 5 which has OH on it, this is as we know is alcoholic group. So it is forming a cyclization between 1 and 5 of the aldehyde group and the alcoholic group of the same molecule. Before rendering the later carbon which is C1 or the aldehyde carbon, it is called asymetric carbon. First we have defined in previous modules that in glucose there are 4 anomeric carbon, 4 chiral center which is 4 asymetric carbon. Here the 5th carbon is asymetric, another carbon atom which is converted into asymetric carbon which is in the straight chain structure which is at the C1 of the aldehyde group. And therefore producing 2 stereoisomers, why are there 2? Because we have defined earlier that if there is 1 carbon, then its 2 raise to the power n, n carbon atom is the number. So if there is 1 more carbon added on the 2, then only 2 will be called stereoisomers which will designate as alpha and beta. Carbon atom number 1, cyclizing after cyclizing has 4 different groups, with which 4 different groups will be attached, that is why it is called asymetric carbon atom and it becomes an asymetric. So this newly created asymetric or chiral carbon is called anomeric carbon atom. Isomeric forms of monosaccharides that differ only in their configuration about amyacetal or hemiketal carbon atoms are called anomers. So carbon, only amyacetal or hemiketal which are made only in intramolecular cyclic structure will differ on that, they will be called anomers and these anomers are in a form of stereoisomers. This is again the diagrammatic representation that we had seen so far that carbon atom number 1 got with 5 and it cyclized it with 1 and till here, hemisacetal was made, while here it became full acetyl and in this we have defined that it became anomeric, why it became anomeric is that it has 4 different groups attached, so it becomes another asymetric or chiral center. It has 4 different groups attached that it has hydroxyl, it has hydrogen at the bottom and on one side it has oxygen and it is attached with ether linkage and on the other side it again this group is attached. So it becomes another asymetric carbon atom or anomeric carbon atom and forming another form of isomers which is called alpha and beta isomers. Now why do we call it alpha? The designation alpha indicates that the hydroxyl group at C1 is trans to CH2, trans means that it is trans to CH2O, this configuration is called as a trans to CH2O, this configuration is called alpha carbon atom or alpha configuration or alpha D gluco pyroneus, gluco pyroneus we will define in the next few modules. Similarly, we have said that in 2 different forms alpha D glucos and beta D glucos, alpha D glucos we have defined that if it is in a trans position, if it is in a similar plane like CH2, UHB is in this plane and UHB is in this plane at carbon atom number 1, so this configuration is called cis and the product name or the molecular name is beta D gluco pyroneus or beta configuration of this isomer. The ordinary crystalline glucos happens to be in the alpha form, till now what we have defined is in the solution form, when we look at crystalline glucos, it is mostly in the alpha form which is convertible into alpha and beta when it is in the solution form.