Editing Glucose (section)

===Optical activity===
Whether in water or the solid form, {{sm|d}}-(+)-glucose is [[Dextrorotation and levorotation|dextrorotatory]], meaning it will rotate the direction of [[polarized light]] clockwise as seen looking toward the light source. The effect is due to the [[chirality]] of the molecules, and indeed the mirror-image isomer, {{sm|l}}-(−)-glucose, is [[Dextrorotation and levorotation|levorotatory]] (rotates polarized light counterclockwise) by the same amount. The strength of the effect is different for each of the five [[tautomer]]s.

The {{sm|d}}- prefix does not refer directly to the optical properties of the compound. It indicates that the C-5 chiral centre has the same handedness as that of [[glyceraldehyde|{{sm|d}}-glyceraldehyde]] (which was so labelled because it is dextrorotatory). The fact that {{sm|d}}-glucose is dextrorotatory is a combined effect of its four chiral centres, not just of C-5; some of the other {{sm|d}}-aldohexoses are levorotatory.<!--CHECK-->

The conversion between the two anomers can be observed in a [[polarimeter]] since pure α-{{sm|d}}-glucose has a specific rotation angle of +112.2° mL/(dm·g), pure β-{{sm|d}}-glucose of +17.5° mL/(dm·g).<ref name=" Hesse">Manfred Hesse, Herbert Meier, Bernd Zeeh, Stefan Bienz, Laurent Bigler, Thomas Fox: ''Spektroskopische Methoden in der organischen Chemie''. 8th revised Edition. Georg Thieme, 2011, {{ISBN|978-3-13-160038-7}}, p. 34 (in German).</ref> When equilibrium has been reached after a certain time due to mutarotation, the angle of rotation is +52.7° mL/(dm·g).<ref name="Hesse" /> By adding acid or base, this transformation is much accelerated. The equilibration takes place via the open-chain aldehyde form.