1.10 S A F E T Y : M A T E R I A L S A F E T Y D A T A S H E E T S
The variety and potential danger of chemicals used in the organic chemistry labora- tory probably exceed that of any laboratory course you have had. It is imperative to understand the nature of the substances with which you are working. Fortunately, the increased emphasis on the proper handling of chemicals has led to a number of publi- cations containing information about the chemical, physical, and toxicological proper- ties of the majority of organic and inorganic compounds used in the experiments in this textbook. A comprehensive source is The Sigma-Aldrich Library of Chemical Safety Data (Reference 8), and it or similar compilations should be available in your library or some other central location. The data provided by these sources are basically
Chapter 1■ Introduction, Record Keeping, and Laboratory Safety 19
summaries of the information contained in the Material Safety Data Sheets (MSDSs) published by the supplier of the chemical of interest. Your instructor may be able to provide these sheets because by federal regulation an MSDS must be delivered to the buyer each time a chemical is purchased.
The information in an MSDS can be overwhelming. For example, the official MSDS for sodium bicarbonate is some six pages long. Even the summaries provided in most compilations are quite extensive, as illustrated in Figure 1.3, which contains 20 Experimental Organic Chemistry■ Gilbert and Martin
Other names Diethyl ether May be harmful by inhalation, ingestion, or skin absorption. Vapor or mist is irritating to the eyes, mucous membranes, and upper respiratory tract.
Causes skin irritation. Exposure can cause coughing, chest pains, difficulty in breathing, and nausea, headache, and vomiting.
Health hazards
CAS Registry No. 60-29-7 First aid
Structure (CH3CH2)2O Incompatibilities
MP –116 °C
Decomposition products
BP 34.6 °C
(760 torr)
Extinguishing media
FP –40 °C Handling and
storage
Appearance Colorless liquid
Toxicity data Man, oral LDL0 260 mg/kg
Spillage
Irritation data Human eye 100 ppm
Disposal
OSHA standard-air: TWA 400 ppm.
Reviews and standards Ether
Name
In case of contact, immediately flush eyes or skin with copious amounts of water for at least 15 min while removing contaminated clothing and shoes. If inhaled, remove to fresh air. If not breathing, give artificial respiration; if breathing is difficult, give oxygen. If ingested, wash out mouth with water. Call a physician.
Oxidizing agents and heat.
Carbon dioxide, dry chemical powder, alcohol, or polymer foam.
Toxic fumes of carbon monoxide, carbon dioxide.
Wear appropriate respirator, chemical-resistant gloves, safety goggles, other protective clothing. Safety shower and eye bath. Do not breathe vapor. Avoid contact with eyes, skin, and clothing. Wash thoroughly after handling.
Irritant. Keep tightly closed. Keep away from heat, sparks, and open flame. Forms explosive peroxides on prolonged storage. Refrigerate. Extremely flammable.
Vapor may travel considerable distance to source of ignition. Container explosion may occur under fire conditions. Danger: Tends to form explosive peroxides, especially when anhydrous. Inhibited with 0.0001% BHT.
Store in clearly labeled containers until container is given to approved contractor for disposal in accordance with local regulations.
Shut off all sources of ignition. Cover with activated carbon adsorbent, place in closed containers, and take outdoors.
Figure 1.3
Summary of MSDS for diethyl ether.
specific data for diethyl ether. Entries regarding the structure and physical properties of the compound, including melting point (mp), boiling point (bp), and flash point (fp), are included, along with its CAS (Chemical Abstracts Service) Registry Number, which is unique for each different chemical substance (see Chap. 26 for a further dis- cussion of CAS Registry Numbers), and RTECS (Registry of Toxic Effects of Chemical Substances) number. Further data are provided concerning its toxicity, the permissible levels set by OSHA for exposure to it in the air you breathe (time-weighted average of 400 ppm), and possible health consequences resulting from contact with the com- pound. For diethyl ether, the entry for “Toxicity Data” represents the lowest recorded lethal concentration for ingestion of the chemical. Valuable information is also given regarding first-aid procedures, classes of substances with which diethyl ether reacts and thus is “incompatible” with, products of its decomposition, and materials suit- able for extinguishing fires involving ether. Finally, protocols for safe handling and storage are included, along with procedures for disposing and cleaning up spills of diethyl ether.
Accessing MSDS information from commercial sources can be very time- consuming, although it is useful to refer to one or more of them if you need more complete MSDS information than is available at the URL associated with this text- book or if you are to use or produce a chemical that is not listed on it. We’ve devel- oped the Web-based MSDSs to provide you with a rapid and convenient way to obtain important information on the chemicals you will be using or producing in the experimental procedures performed when using this textbook. The data we’ve provided on the website for this textbook are much more abbreviated than those in other sources, as seen in Figure 1.4. In developing our summaries of MSDS data, we’ve focused on just those data most relevant to your needs in the introductory organic laboratory.
We noted in the discussion of notebook formats (Sec. 1.6) that you may be required to summarize MSDS data in your laboratory book. This could be a daunting assignment, given the amount of information with which you might be faced, as illustrated in Figure 1.3. To assist you in doing this, we have provided one possible format for a summary in Figure 1.5. A summary for a particular chemical has to be provided only once and can be recorded at the end of your laboratory notebook on pages reserved for that purpose. Whenever the chemical is encoun- tered in later experiments, you would only need to refer to the location of the sum- mary of its MSDS information. However, you should reread the MSDS information so that you can continue to handle the chemical properly. This same recommenda- tion applies if you have a file of MSDS-related printouts from the website for this textbook.
To summarize, you may think that reading about and recording data like those contained in Figures 1.3–1.5 is not a good investment of time. This is absolutely wrong! By knowing more about the chemicals that are used in the laboratory, you will be able to work safely and to deal with accidents, should they occur. The end result will be that you accomplish a greater amount of laboratory work and have a more valuable educational experience.
1.11 S A F E T Y : D I S P O S A L O F C H E M I C A L S
The proper disposal of inorganic and organic chemicals is one of the biggest respon- sibilities that you have in the organic laboratory. Your actions, and those of your labmates, can minimize the environmental impact and even financial cost to your Chapter 1■ Introduction, Record Keeping, and Laboratory Safety 21
See MSDSs
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school for handling the waste chemicals that are necessarily produced in the experi- ments you do.
The experimental procedures in this textbook have been designed at a scale that should allow you to isolate an amount of product sufficient to see and manipulate, but 22 Experimental Organic Chemistry■ Gilbert and Martin
CAS No.
Fire
Inhalation
Skin
Eyes
Severe fire hazard, severe explosion hazard; may form explosive peroxides; vapors or gases may ignite at distant ignition sources.
No flames, no sparks, no contact with hot surfaces.
Alcohol-resistant foam, carbon dioxide, regular dry chemical powder, water.
Central nervous system depression with drowsiness, dizziness, nausea, headache, and lowering of the pulse and body temperature.
Central nervous system depression with nausea, vomiting, drowsiness,
dizziness; stomach may become promptly distended, which may hinder breathing.
Irritation, defatting, and drying of the skin.
Painful inflammation. Safety goggles. Thoroughly flush eyes with water for several min, removing contact lenses if possible, and seek medical advice immediately.
Carcinogenicity Not a known carcinogen. Mutagenicity Possible mutagen.
Ingestion Do not eat or drink in the
laboratory.
Seek medical advice immediately.
Protective gloves and clothing.
Remove contaminated clothes/jewelry;
thoroughly wash skin with soap and water;
and seek medical advice.
Ventilation, local exhaust. Remove from exposure immediately and seek medical advice.
Types of Hazards/Exposures
Acute
Hazards/Symptoms Prevention First Aid/Fire
PS Color Odor FP BP MP d VP VD Sol
60-29-7 Liquid 40 35 –116
442
@ 20
6.9 2.6 @ 20 0.7
Colorless Sweet
Diethyl Ether C4H10O
For more detailed information, consult the Material Safety Data Sheet for this compound.
Abbreviations: CAS No. = Chemical Abstracts Service Registry Number; PS = physical state; FP = flash point (°C); BP = boiling point (°C) @ 760 torr unless otherwise stated; MP = melting point (°C); d = density or specific gravity (g/mL); VP = vapor pressure (torr) at specified temperature (°C); VD = vapor density relative to air (1.0); Sol = solubility in water (g/100 mL) at specified temperature; N/A = not available or not applicable.
Figure 1.4
Example of MSDS data provided at the website for this textbook.
they also involve the use of minimal quantities of reactants, solvents, and drying agents.
Bear in mind, however, that minimizing the amounts of chemicals that are used is only the first part of an experimental design that results in the production of the least possi- ble quantity of waste. The second part is to reduce the amounts of materials that you, the experimentalist, define as waste, thereby making the material subject to regulations for its disposal. From a legal standpoint, the laboratory worker is empowered to declare material as waste; that is, unneeded materials are not waste until you say they are! Con- sequently, a part of most of the experimental procedures in this textbook is reduction of the quantity of residual material that eventually must be consigned to waste. This means some additional time will be required for completion of the experiment, but the benefits—educational, environmental, and economic in nature—fully justify your efforts. The recommended procedures that should be followed are described under the heading Wrapping It Up.
How do you properly dispose of spent chemicals at the end of an experiment?
In some cases this involves simply flushing chemicals down the drain with the aid of large volumes of water. As an example, solutions of sulfuric acid can be neutral- ized with a base such as sodium hydroxide, and the aqueous solution of sodium sulfate that results can safely be washed into the sanitary sewer system. However, the environmental regulations that apply in your particular community may require use of alternative procedures. Be certain to check with your instructor before flushing any chemicals down the drain!
For water-insoluble substances, and even for certain water-soluble ones, this option is not permissible under any circumstances, and other procedures must be followed. The laboratory should be equipped with various containers for disposal of liquid and solid chemicals; the latter should not be thrown in a trash can, because this exposes maintenance and cleaning personnel to potential danger, and it is envi- ronmentally unsound. The containers must be properly labeled as to what can be put in them, because it is very important for safety and environmental reasons that different categories of spent chemicals be segregated from one another. Thus, you are likely to find the following types of containers in the organic laboratory: haz- ardous solids, nonhazardous solids, halogenated organic liquids, hydrocarbons, and oxygenated organic liquids. Each student must assume the responsibility for seeing that her or his spent chemicals go into the appropriate container; otherwise dangerous combinations of chemicals might result and/or a much more expensive method of disposal be required.
Chapter 1■ Introduction, Record Keeping, and Laboratory Safety 23
Diethyl Ether May be harmful by inhalation, ingestion, or skin absorption.
Avoid contact with eyes, skin, and clothing. In case of contact, immediately flush eyes or skin with copious amounts of water. Keep away from hot surfaces, sparks, and open flames. Extremely flammable. Vapor may travel considerable distance to source of ignition. If spilled, shut off all sources of ignition. Extinguish fire with carbon dioxide, dry chemical extinguisher, foam, or water.
Health Hazards, First Aid, Incompatibilities, Extinguishing Media, and Handling
Compound
Figure 1.5
Abstract of MSDS for diethyl ether.
R E F E R E N C E S
1. Lunn, G.; Sansone, E. B. Destruction of Hazardous Chemicals in the Laboratory, 2nd ed., John Wiley & Sons, New York, 1994. A handbook providing procedures for decom- position of materials or classes of materials commonly used in the laboratory.
2. Committee on Hazardous Substances in the Laboratory. Prudent Practices for Dis- posal of Chemicals from Laboratories, National Academy Press, Washington, D.C., 1995. An excellent reference containing information for the minimization of waste generated in the laboratory and for the proper handling and disposal of waste chemicals, both organic and inorganic. Available at no cost online: www.nap.edu/
catalog.php?record_id=4911#toc.
3. Young, J. A., ed. Improving Safety in the Chemical Laboratory: A Practical Guide, 2nd ed., John Wiley & Sons, New York, 1991. A book containing thorough discus- sions of the full range of safe practices in the laboratory.
4. Mahn, W. J. Fundamentals of Laboratory Safety: Physical Hazards in the Academic Labo- ratory, Van Nostrand Reinhold, New York, 1991.
5. Lide, D. A., ed. CRC Handbook of Chemistry and Physics, annual editions, CRC Press, Boca Raton, FL. Available online to subscribers: www.hbcpnetbase.com.
6. Speight, J. G., ed. Lange’s Handbook of Chemistry, 16th ed., McGraw-Hill, New York, 2005. Available online to subscribers: knovel.com/web/portal/browse/
display?_EXT_KNOVEL_DISPLAY_bookid=1347&VerticalID=0.
7. Luxon, S. G., ed. Hazards in the Chemical Laboratory, 16th ed., The Royal Society of Chemistry, London, 1992.
8. Lenga, R. E. and Votoupal, K. L., eds. The Sigma-Aldrich®Library of Chemical Safety Data, 2nd ed., Sigma-Aldrich, Milwaukee, WI, 1988.
9. O’Neil, M. J., ed. Merck Index of Chemicals and Drugs, 14th ed., Merck and Co., Rahway, NJ, 2006. Available online to subscribers: www.merckbooks.com/mindex/online.html.
10. Armour, M. A. Hazardous Laboratory Chemical Disposal Guide, 3rd ed., CRC Press, Boca Raton, FL, 2003.
24 Experimental Organic Chemistry■ Gilbert and Martin
H I S T O R I C A L H I G H L I G H T
The Importance of Record Keeping
Alexander Graham Bell is a household name, whereas that of Elisha Gray, a formidable competitor of Bell’s in the race to invent the telephone, is not. Therein lies a tale of the importance of accurate record keeping.
Both Bell and Gray were originally interested in inventions associated with transmitting information electrically, and Gray’s accomplishments in this area prior to 1875 far exceeded those of Bell. Indeed, Gray’s considerable inventive abilities had resulted in his being awarded a number of patents associated with telegraphy by 1870, and in 1872 he became a cofounder of what was to become the Western Electric Company.
As early as the winter of 1866, Gray had been intrigued by the possibility of a “harmonic multiple telegraph system,” which is the basis of telephonic communica- tion because it permits transmitting tone or pitch in the form of electrical signals. However, he focused his attention on other telegraphic devices and managing the early growth of his company. It was not until 1874 that he could return to his research endeavors.
Meanwhile, Bell’s lifelong interest in educating the deaf had led him toward studying the transmission of speech electrically and he, like Gray, became inter- ested in the harmonic telegraph. His work, although (Continued)
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Chapter 1■ Introduction, Record Keeping, and Laboratory Safety 25
not hindered by his having to manage an emerging company, was impeded by the demands made by his duties as a professor, tutor, and promoter of methods for teaching the deaf. Nonetheless, because of his research in telegraphy on November 23, 1874, he was able to write the following momentous words in a letter to his parents: “Please keep this paper as a record of the conception of the idea [emphasis our own] in case any one else should at a future time dis- cover that the vibrations of a permanent magnet will induce a vibrating current of electricity in the coils of an electromagnet.”
This concept of a “harp apparatus” to induce a variable current comprises a fundamental basis of telephonic speech, and Bell’s foresight in instructing his parents to keep the dated letter as a record of his idea proved to be the crucial element in the legal wran- gling that eventually developed between Bell and Gray as to who had precedent for this invention. Gray may have conceived of the principles for a harmonic multi- ple telegraph as early as the spring of 1874, but he failed to include his ideas in patent renewals he filed in January of 1875. However, he filed a patent applica- tion on February 23, 1876, that did outline his concept, predating Bell’s own application by two days. Deter- mining to whom the patent would be awarded, though, depended on the respective dates of conception by the two inventors. It was the written record, contained in Bell’s letter to his parents, that led to his being awarded the first key patent for the harmonic multiple telegraph. Unfortunately for Gray, his claim of conceiv- ing the same idea at an even earlier date had no corre- sponding documentation.
It was yet a second dated letter written by Bell that established his priority in conceiving the final funda- mental principle for the modern telephone: variable resistance. This permits the amplitude as well as the pitch of a sound to be modulated electrically. Although he did not file a patent for this concept until February 14, 1876, an action again contested by Gray, Bell only three weeks later was awarded patent No. 174,465, which is generally considered the key patent for the invention of the telephone. The rest is history!
A fascinating description of the path that led Alexander Graham Bell to inventing the telephone is found online at www2.iath.virginia.edu/albell/
homepage.html, and the definitive biography of his life is provided by the following reference: Robert V.
Bruce,Alexander Graham Bell and the Conquest of Solitude, Ithaca, NY: Cornell University Press, 1973, 564 pp.
Relationship of Historical Highlight to Experiments
The importance of completely documenting the experiments you perform in the laboratory cannot be overemphasized. Writing down the observations you make and the date on which you make them may not be the key to winning litigation over patent rights, as was the case with Bell’s inventions, but there is always the possibility that they will. A more likely outcome is that such documentation will demonstrate your competence in the laboratory and may result in winning the contest for the top grade in the class!
H I S T O R I C A L H I G H L I G H T The Importance of Record Keeping (Continued))
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Techniques and Apparatus
In this chapter we introduce the basic experimental techniques and associated glassware and apparatus that are commonly used in the organic chemistry labora- tory. In some instances, only the practical aspects of a particular technique are dis- cussed in this chapter, and the theoretical principles underlying it are presented in later chapters.
It is important to skim the contents of this entire chapter, but we do not recom- mend that you read all parts of it in detail at this time. We make reference to spe- cific techniques and/or apparatus as part of the procedures for many experiments;
thus, when you are preparing for an experiment, carefully read the appropriate sections of this chapter. This should be done prior to entering the laboratory to perform the experimental procedure!
2.1 G L A S S W A R E : P R E C A U T I O N S A N D C L E A N I N G
Laboratory experiments in organic chemistry are commonly conducted in special- ized glassware that is usually expensive. Since you are responsible for maintaining your glassware, you should follow proper procedures for safely handling and cleaning it. Failure to do so is likely to result in injury to yourself, breakage, or dirty glassware that is difficult to clean.
The cardinal rule in handling and using laboratory glassware is Never apply undue pressure or strain to any piece of glassware. Strained glassware may break at the moment the strain is induced, when it is heated, or even after standing for a period of time.
When setting up a glassware apparatus for a particular experiment, be sure that the glassware is properly positioned and supported to avoid breakage (Sec. 2.4).
Sometimes it is necessary to insert thermometers or glass tubes into rubber stop- pers or rubber tubing. If you have to force it, do not do it! Either make the hole slightly larger or use a smaller piece of glass. You may also lubricate the glass tube with a little glycerol prior to insertion into stoppers or tubing. When inserting a glass tube into a stopper or tubing, always grasp the glass piece as close as possible to the rubber part. It is also wise to wrap a towel around the glass tube and the rubber stopper while insert- ing the tube. This usually prevents a serious cut in the event the glass happens to break.
Glassware should be thoroughly cleaned immediately after use. Residues from chemical reactions may attack the surface of the glass, and cleaning becomes more difficult the longer you wait. Before washing glassware, it is good practice to wipe off any lubricant or grease from standard-taper ground-glass joints (Sec. 2.2) with a towel or tissue moistened with a solvent such as hexane or dichloromethane. This prevents the grease from being transferred during washing to inner surfaces of the 27
C H A P T E R 2
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