**Measurement**

The α and β anomers are diastereomers of each other and usually have different specific rotations. A solution or liquid sample of a pure α anomer will rotate plane polarised light by a different amount and/or in the opposite direction than the pure β anomer of that compound. The optical rotation of the solution depends on the optical rotation of each anomer and their ratio in the solution.

For example if a solution of β-D-glucopyranose is dissolved in water, its specific optical rotation will be +18.7. Over time, some of the β-D-glucopyranose will undergo mutarotation to become α-D-glucopyranose, which has an optical rotation of +112.2. Thus the rotation of the solution will increase from +18.7 to an equilibrium value of +52.5 as some of the β form is converted to the α form. The equilibrium mixture is actually about 64% of β-D-glucopyranose and about 36% of α-D-glucopyranose, though there are also with traces of the other forms including furanoses and open chained form.

The observed optical rotation of the sample is the weighted sum of the optical rotation of each anomer weighted by the amount of that anomer present. Therefore one can use a polarimeter to measure the rotation of a sample and then calculate the ratio of the two anomers present from the enantiomeric excess, as long as one knows the rotation of each pure anomer. One can monitor the mutarotation process over time or determine the equilibrium mixture by observing the optical rotation and how it changes.

Read more about this topic: Mutarotation

### Other articles related to "measurement, measurements":

... due to Spearman (1904), to "rid a correlation coefficient from the weakening effect of

**measurement**error" (Jensen, 1998), a phenomenon also known as ... In

**measurement**and statistics, it is also called disattenuation ... The correlation between two sets of parameters or

**measurements**is estimated in a manner that accounts for

**measurement**error contained within the estimates of those parameters ...

... Inch as a

**measurement**of rain, measured by a rain gauge Inch of mercury, unit of pressure Inch of water, unit of pressure Scottish inch, Scottish unit of

**measurement**Column inch, unit of ...

... distribution in the interior of an object from external capacitance

**measurements**... Potential applications include the

**measurement**of flow of fluids in pipes and

**measurement**of the concentration of one fluid in another, or the ... in widespread use the idea of using capacitance

**measurement**to form images is attributed to Maurice Beck and co-workers at UMIST in the 1980s ...

**Measurement**Tower

... A

**measurement**tower is a free standing tower or a removed mast, which carries measuring instruments with meteorological instruments such as thermometers and wind velocity measurers ... Beside

**measurement**towers, which are equipped with meteorological measuring instruments, there are also measuring towers for measuring the radiation pattern of antennas ...

**Measurement**- Definitions and Theories - Quantum Mechanics

... In quantum mechanics, a

**measurement**is an action that determines the location of an object, its momentum, its polarity (if it is a photon), etc ... Before a

**measurement**is made, the wavefunction of what is to be measured gives the range of probabilities for the outcomes of

**measurement**, but when a

**measurement**is ... The unambiguous meaning of the

**measurement**problem is an unresolved fundamental problem in quantum mechanics ...

### Famous quotes containing the word measurement:

“That’s the great danger of sectarian opinions, they always accept the formulas of past events as useful for the *measurement* of future events and they never are, if you have high standards of accuracy.”

—John Dos Passos (1896–1970)