Polarimeter

Overview

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 (−).

Procedure

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

Results

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 Application and Summary 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. 跳至... 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 此集合中的视频: Now Playing Polarimeter Organic Chemistry II 99.8K Views Cleaning Glassware Organic Chemistry II 123.1K Views Nucleophilic Substitution Organic Chemistry II 99.2K Views Reducing Agents Organic Chemistry II 42.8K Views Grignard Reaction Organic Chemistry II 148.8K Views n-Butyllithium Titration Organic Chemistry II 47.6K Views Dean-Stark Trap Organic Chemistry II 99.8K Views Ozonolysis of Alkenes Organic Chemistry II 66.8K Views Organocatalysis Organic Chemistry II 16.6K Views Palladium-Catalyzed Cross Coupling Organic Chemistry II 34.2K Views Solid Phase Synthesis Organic Chemistry II 40.8K Views Hydrogenation Organic Chemistry II 49.2K Views Polymerization Organic Chemistry II 93.7K Views Melting Point Organic Chemistry II 149.6K Views Infrared Spectroscopy Organic Chemistry II 214.0K Views 政策使用条款隐私联系我们向图书馆推荐 JoVE 新闻简报科研 JoVE Journal 技术专题合集 JoVE Encyclopedia of Experiments 档案教育 JoVE Core JoVE Science Education JoVE Lab Manual JoVE Business JoVE Quiz JoVE Playlist Faculty Site 发表概述发表流程编辑部范围和政策同行评审常见问题提交稿件图书馆员概述客户评价订阅访问权限资源图书馆咨询委员会常见问题关于 JoVE 概述管理层博客 JoVE Help Center JoVE Sitemap 版权所属 © 2025 MyJoVE 公司版权所有，本公司不涉及任何医疗业务和医疗服务。