Aspartame is an artificial sweetener from the non-sugar groups that sakarida widely used for diet products or low-calorie products. Aspartame is sweeter about 180-200 times than regular sugar with the same concentration. This means that by using these sweeteners, we only need 1 / 200 times less aspartame than using regular sugar.

Aspartame is none other than the methyl esters of natural amino acids dipeptida namely aspartic acid and phenylalanine. Aspartame is found by accident by James Schlatter, a chemist at GD Searle Co. in 1965. Schlatter has unexpectedly synthesize aspartame at the time he made anti-pain medication.

Aspartame Synthesis
There are 3 reagents required for the synthesis of aspartame, methanol, phenylalanine, and aspartic acid. Starting materials needed to make the aspartame is rasemat mixture of phenylalanine, L-phenylalanine only be used for synthesis. L and D isomers of phenylalanine are separated by the addition Ac2O and NaOH, the reaction was then reacted with Porcine Kidney Acylase and then extracted with organic solvents followed by pickling. D-phenylalanine will be located in the organic phase whereas the L-phenylalanine will be found in the water phase.

Clusters acid L-phenylalanine is then converted into methyl esters using methanol and HCl.Last reacting methyl esters of phenylalanine with aspartic acid to produce dipeptida structure. This stage because it requires several stages of acid functional groups on the aspartic acid must be protected so as not to react, we need only one of two aspartic acid functional groups which will react with amine functional groups on the phenylalanine methyl ester.
The nature of Chemical Aspartame
Aspartame has the chemical formula C14H18N2O5 and molecular weight 294.31 Aspartame has two functional groups that can be ionized and both there at the residues aspartic acid. At neutral pH, aspartame is in two forms ionized. Aspartame is stable maximum at pH 4.3. Aspartame at room temperature form of white powder that does not smell and point leburnya 248-2500C. 

Why Aspartame is called Sugar With 0 Calories?
In order for us to know why aspartame is called 0-calorie sugar then let us do a simple calculation. Suppose a product bottled beverages with 330 mL of sugar requires 50 grams for a certain sweetness level in accordance with the standard drink, so by using aspartame we only need: (we use the level of sweetness of aspartame is 200 times that of regular sugar)

Grams of aspartame are required:

= 1 / 200 x 50 g

= 0.25 g

Aspartame is metabolized in the body into their constituent components namely aspartic acid, phenylalanine, and methanol. Like other amino acids, each gram of amino acid is metabolized in the body to produce 4 calories, because we have then 0.25 g of aspartame:

Mol aspartame

= 0.25 / 294.31

= 8.5 x10-4 mol

Aspartame breakdown reaction to constituent:

C14H18N2O5 + 3H2O +2 H + -> C4H7NO4 + C9H11NO2 + CH3OH + H2O

Comparison mol aspartic acid and phenylalanine is 1:1 then the mass of each of these amino acids are:

Aspartic acid

= 8.5 x10-4 mol x 133 = 0.11 g

Phenylalanine

= 8.5 x10-4 mol x 165 = 0.14 g

Calories produced are:

= (0.11 g + 0.14 g) x 4 = 1 calorie

From the above calculation can be seen that by consuming beverages using aspartame as a sweetener, we only get just 1 calorie. This is tantamount to saying calories can ignore it because it was the aspatam can be used as a substitute for sugar with 0 calories.

Reference:

• http://www.3dchem.com/molecules.asp?ID=24#
• http://www.chemistrydaily.com/chemistry/Aspartame
• http://www.chm.bris.ac.uk/webprojects2000/srogers/sarah.html
• http://www.elmhurst.edu/~chm/vchembook/549aspartame.html
• http://chemicalland21.com/lifescience/foco/ASPARTAME.htm