' Chirality' ⢠A!
Mesocompounds:'Have!two!or!more!stereocenters!and!a!plane!of!symmetry.'Achiral!compound.'
' ' Chirality' • • • • • •
A!molecule!(or!object)!that!is#not#superposable!on!its!mirror!image!is!described!as!being! chiral.'! They!show!handedness!and!you!cannot!draw!a!plane!through!it! In!contrast,!a!molecule!(or!object)!that!is#superposable!on!its!mirror!image!(Note:! everything'has!to!match)#is!achiral.!! An!object!or!molecule!is!achiral!if!it!has!a!plane!of!symmetry!! Many!chiral!molecules!contain!an!asymmetric'carbon'centre,!a!so=called!stereogenic' centre.! This!is!easily!identified!as!a!carbon!atom!attached!to!four'different'groups.'!
Properties'&'chirality'' • • • •
An!optically'active!substance!rotates!the!plane!of!polarised!light!and!this!rotation,!or! optical!activity,!is!detected!and!measured!in!a!polarimeter.!! After!polarised!light!is!generated!it!passes!through!the!sample!cell.!After!emerging!from!the! cell,!the!light!passes!through!a!second!polarising!filter!and!finally!the!detector/eye.!! If!the!sample!is!optically#inactive,!the!plane!is!unchanged!and!no!rotation!is!detected.!! If!the!sample!is!optically#active,#the!plane!of!polarisation!is!rotated.!The!polarimeter!is!used! to!determine!both!the!direction'and'magnitude'of!the!rotation.!!
Polarimeter'' • • • •
Enantiomers!can!be!distinguished!by!how!they!interact!with!a!plane!of!polarised!light.!They! are!optical'isomers.'! Ordinary!light:!consists!of!waves!vibrating!in!all!planes!perpendicular!to!its!direction!of! propagation! Plane'polarized'light:'consists!of!waves!vibrating!only!in!one!plane! Polarimeter:'a!device!for!measuring!the!extent!of!rotation!of!plane!polarized!light.! Polarising!filters!are!made!from!calcite!or!polaroid!sheeting!!
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' ' Chirality' • • • • • •
A!molecule!(or!object)!that!is#not#superposable!on!its!mirror!image!is!described!as!being! chiral.'! They!show!handedness!and!you!cannot!draw!a!plane!through!it! In!contrast,!a!molecule!(or!object)!that!is#superposable!on!its!mirror!image!(Note:! everything'has!to!match)#is!achiral.!! An!object!or!molecule!is!achiral!if!it!has!a!plane!of!symmetry!! Many!chiral!molecules!contain!an!asymmetric'carbon'centre,!a!so=called!stereogenic' centre.! This!is!easily!identified!as!a!carbon!atom!attached!to!four'different'groups.'!
Properties'&'chirality'' • • • •
An!optically'active!substance!rotates!the!plane!of!polarised!light!and!this!rotation,!or! optical!activity,!is!detected!and!measured!in!a!polarimeter.!! After!polarised!light!is!generated!it!passes!through!the!sample!cell.!After!emerging!from!the! cell,!the!light!passes!through!a!second!polarising!filter!and!finally!the!detector/eye.!! If!the!sample!is!optically#inactive,!the!plane!is!unchanged!and!no!rotation!is!detected.!! If!the!sample!is!optically#active,#the!plane!of!polarisation!is!rotated.!The!polarimeter!is!used! to!determine!both!the!direction'and'magnitude'of!the!rotation.!!
Polarimeter'' • • • •
Enantiomers!can!be!distinguished!by!how!they!interact!with!a!plane!of!polarised!light.!They! are!optical'isomers.'! Ordinary!light:!consists!of!waves!vibrating!in!all!planes!perpendicular!to!its!direction!of! propagation! Plane'polarized'light:'consists!of!waves!vibrating!only!in!one!plane! Polarimeter:'a!device!for!measuring!the!extent!of!rotation!of!plane!polarized!light.! Polarising!filters!are!made!from!calcite!or!polaroid!sheeting!!
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