Polarimeter

Panoramica

Source: Vy M. Dong and Diane Le, Department of Chemistry, University of California, Irvine, CA

This experiment will demonstrate the use of a polarimeter, which is an instrument used to determine the optical rotation of a sample. Optical rotation is the degree to which a sample will rotate polarized light. Optically active samples will rotate the plane of light clockwise (dextrorotatory), designated as d or (+), or counterclockwise (levorotatory), designated as l or (−).

Procedura

1. Preparing the Polarimeter

Turn on instrument and let it warm up for 10 min.
Make sure instrument is set to "optical rotation" mode.
Prepare a blank sample in the polarimeter cell (1.5 mL total sample volume, 1 dm in length) containing only CHCl₃. Make sure there are no air bubbles present.
Place the blank cell in the holder and press "zero."

2. Preparation of Analyte Sample

Prepare a stock solution of 10

Risultati

Representative results for the measurement and calculation of specific rotation for Procedures 1-4.

Procedure Step	Reading on polarimeter
1.4	0.000
3.2	+0.563
4.1	[α]₂₅^D = +77° (c 0.73, CHCl₃) Log in or to access full content. Learn more about your institution’s access to JoVE content here Applicazione e Riepilogo In this experiment, we have demonstrated the principles behind the polarimeter and how to measure and calculate the specific rotation of an optically active compound. The polarimeter is an important instrument in the fine-chemical and pharmaceutical industries to assess the identity, purity, and quality of a compound. It is specifically used for the measurement of optical rotation of chiral compounds, which can be used to distinguish the identity of two enantiomers by confirming whether it is Log in or to access full content. Learn more about your institution’s access to JoVE content here Tags Polarimeter Purity Assessment Chemical Properties Enantiomers Mirror image Variants Biological Activities Pharmaceuticals Drug Thalidomide Principles Of Polarimetry Setup And Operation Applications Organic Compounds Stereocenters Chiral Compounds Mirror image Isomers Enantiomers Physical Properties Optics 1. Preparing the Polarimeter Turn on instrument and let it warm up for 10 min. Make sure instrument is set to "optical rotation" mode. Prepare a blank sample in the polarimeter cell (1.5 mL total sample volume, 1 dm in length) containing only CHCl₃. Make sure there are no air bubbles present. Place the blank cell in the holder and press "zero." 2. Preparation of Analyte Sample Prepare a stock solution of 10-15 mg of the chiral analyte in 1.5 mL CHCl₃. Note the exact amount of compound used. 3. Measuring Optical Rotation Fill the cell with 1.5 mL of the prepared stock solution containing the sample. Place the cell in the holder and press "measure." The machine readout will give the optical rotation value. Remember to record the temperature as well. 4. Calculation of Specific Rotation The specific rotation of a compound is defined by the following equation: where α is the optical rotation value given by the polarimeter, l is the cell pathlength in dm, and c is the concentration of the solution in g/mL. Vai a... 0:00 Overview 0:49 Principles of Polarimetry 3:51 Initialization of the Polarimeter 4:24 Calibration and Measurement 5:23 Applications 6:52 Summary Video da questa raccolta: Now Playing Polarimeter Organic Chemistry II 99.7K Visualizzazioni Pulizia della vetreria Organic Chemistry II 122.8K Visualizzazioni Sostituzione nucleofila Organic Chemistry II 99.0K Visualizzazioni Agenti riducenti Organic Chemistry II 42.7K Visualizzazioni Reazione di Grignard Organic Chemistry II 148.6K Visualizzazioni Titolazione di n-butillitio Organic Chemistry II 47.6K Visualizzazioni Dispositivo di Dean Stark Organic Chemistry II 99.6K Visualizzazioni Ozonolisi degli alcheni Organic Chemistry II 66.6K Visualizzazioni Organocatalisi Organic Chemistry II 16.5K Visualizzazioni Reazione di accoppiamento catalizzata da palladio Organic Chemistry II 33.8K Visualizzazioni Sintesi in fase solida Organic Chemistry II 40.7K Visualizzazioni Idrogenazione Organic Chemistry II 48.7K Visualizzazioni Polimerizzazione Organic Chemistry II 93.3K Visualizzazioni Punto di fusione Organic Chemistry II 149.0K Visualizzazioni Spettroscopia infrarossa Organic Chemistry II 213.5K Visualizzazioni Riservatezza Condizioni di utilizzo Politiche Contattaci SUGGERISCI JOVE ALLA BIBLIOTECA Newsletter di JoVE Ricerca JoVE Journal Raccolta di metodi JoVE Encyclopedia of Experiments Archivio Didattica JoVE Core JoVE Science Education JoVE Lab Manual JoVE Business JoVE Quiz JoVE Playlist Faculty Site Autori Panoramica Processo di pubblicazione Comitato editoriale Ambito e politiche Revisione paritaria Domande frequenti Invia Personale delle biblioteche Panoramica Testimonianze Abbonamenti Accesso Risorse Comitato consultivo della biblioteca Domande frequenti CHI SIAMO Panoramica Direzione Blog JoVE Help Center JoVE Sitemap Copyright © 2025 MyJoVE Corporation. Tutti i diritti riservati