edited by
TIM CHAMPION
safety tips
Johnson C. Smith University Charlone. NC 28218
Safe Disposal of Highly Reactive Chemicals George ~ u n n 'and Eric 6.Sansone PRIIDvnCorp, Environmental Control and Research Program, NCI-Frederick Cancer Research and Development Center, P.O.B& B, Frederick MD 21702 Althoueh ., much attention has been focused in recent years on the safe handling and disposal ofcarcinogenic and Loxir chemicals ( 1 lens attention has been paid to the safe disposal uf highly rwctlvc chemicals althouRh the halards posed bv thew comuounds are detailed in Matenal Safety h a sheets and other references (2,3). We wish to report the results of a study of the safe disposal of some highly in reactive compounds.~~ecause they can create the laboratory, disposal of some sulfur-containing compounds also was investigated. Some procedures are based on information obtained from the literature; others were develoned hv " the authors. All nrocedures have been carried out for the compounds listed'in the table by the authors. Full details are given in the Experimental Procedure section A number of highly reactive chemicals can be degraded by allowing them to react with water in a carefully controlled fashion. These include metallic barium, calcium, and strontium, and the compounds calcium carbide, chlorotrimethylsilane, dichlorodimethylsilane, lithium aluminum hydride, lithium hydride, methyltrichlorosilane, potassium t-butoxide, silicon tetrachloride, sodium ethoxide, and sodium methoxide. In some cases crushed ice (chlorosulfonic acid) or crushed ice and water (phosphorus pentoxide) are used to moderate the vigor of the reaction by absorbing the heat produced. More reactive materials can be reacted with a n alcohol to moderate the reaction. Thus, butyllithium, potassium hydride, and sodium hydride can be reacted with butanol; lithium, lithium aluminum hydride, sodium, and sodium amide can be reacted with ethanol; potassium can be reacted with t-butvl alcohol or t-amvl alcohol. Some materials require the aidition of 2.5 M sobium hydroxide solution to make the hydrolysis go to completion (acetic anhydride, acetyl chloride, benzenesulfonyl chloride, benzoyl chloride, dimethylcarbamoyl chloride, methanesulfonyl chloride, phosgene in toluene solution, propionyl chloride, sulfuryl chloride, thionyl chloride, p-toluenesulfonyl chloride, triphosgene). Acid also may be required. For example, the demadation of sodium borohvdride reauired the presence of acetic acid and magnesium required-the prese&e of hydrochloric acid. Oxidizine aeents were reduced with sodium metabisulfite solt,tio~,b~omine, t-l)utyl hydroperoxide, t-hutyl hypochlorite. calcium hwuchlorite. chloramine-'l: m-chlnroverbenzoic acid, N-chlorosucci'nimide, hydrogen peroxide (30%). iodine.. ~. e r a c e t i acid. c potassium permanaanate, sodium hypochlorite, and sodium peroxid.e,. ~ u l t i k o n t a i n ing compounds were oxidizi.d with 5.2501 sodium hypo-
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'Current address: Laboratory of Pharmaceutical Chemistty, NCIFrederick Cancer Research and Development Center, P. 0.Box 6, Frederick, MD 21702-1201.
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Journal of Chemical Education
chloritc solution (eg., Clorox bleach, (butancthid, hutyl disulfide, carbon disulfide, ethanethiol, ethyl disulfide, methyl disulfide, sudium sulfide, and thiophenol . Sodium cyanoborohydride was also oxidized wiih sodium hypochlorite; red and white phosphorus were oxidized with potassium bromate and copper sulfate, respectively Experimental Procedure CAUTION:These procedures are potentially hazardous. All reactions should be done in a properly functioning chemical fume hood using a safety shield if appropriate. Proper pratective clothing including eye protection should be worn. These chemicals are hazardous and the hazards associated
operations should be conducted away from flammable solvents. The presence of a nonflammable board or cloth far smothering the reaction, as well as an appropriate fire extinguisher, may be advisable. If possible, do the reactions in small batches to minimize risk. Most of these reactions are rxuthrrmlc. Befim dmwdmc any reaction rnlxture, examInr i r carefully fi,r unrearred rtarung matcnal. If you do nor completely understand these procedures do not attempt them. General Procedure In general, 5 g or 5 mL of the compound to be degraded is added to the appropriate reagent with stiring a t such a rate that the reaction does not get out of hand. When the reaction is over the reaction inixture should be examined for unreacted starting material and discarded in full compliance with all local and national regulations and after consultation with the local wastewater system operator. The various reacents that have been used are &en in the table together 4 t h the appropriate weight-voiume or volume-volume ratio. For example, acetic anhydride can be degraded by adding it to 2.5 M sodium hydroxide solution. The term 20xmeans that for each 5 mL of acetic anhydride 100 mL of 2.5 M sodium hydroxide solution was used. Frequently, it is helpful to monitor the temperature of the reaction so that the end point can be determined. I n some cases a specific analytical technique can be used to monitor for com~letenessof destruction. and these instances are described. These reactions weregenerally ranird out with c c>xccptfor those 5 e or 5 ml. of the matwi;il to l ~ dcrrraded inldicated l00x when 1g or 1mL o h a t e r i a l w i s added to 100 mL of the appropriate reagent with stirring. Specific Procedures Benzenesulfonyl Chloride and p-ToluenesulfonylChloride A. Add 5 mL of benzenesulfonyl chloride or 5 g afp-toluene-
sulfonyl chloride to 100 mL of 2.5 M sodium hydroxide solution. Cover and stir the reaction at room tem~erature
Destruction of Highly Reactive Chemicals Compound acetic anhydride acetyl chloride barium benzenesulfonylchloride benzoyl chloride
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borane THF complex bromine butanethiol butyl disulfide t-butyl hydroperoxide t-butyl hypochlorite butyllithium calcium calcium carbide calcium hydride calcium hypochlorite carbon disulfide Chloramine-T mchloroperbenzoic acid
chlorosulfonic acid chlorotrimethylsilane dichlorodimethylsilane dimethylcarbamoylchloride ethanethiol ethyl disulfide hydrogen peroxide (30%) iodine lithium
React with 2.5 M sodium hydroxide solution 2ox 2.5 M sodium hydroxide solution 20x water 1OOx see text 2.5 M sodium hydroxide solution 20x see text 10% (wlv) sodium metabisulfite solution 100xa see text see text 10% (wh) sodium metabisulfite solution 20xa 10% (wh) sodium metabisulfite solution 20xa see tea water loox water 50x crushed ice 50x 10% (wh) sodium metabisulfite solution 20xa see text 10% (wlv) sodium metabisulfite solution 20xa 10% (w/v) sodium metabisulfite solution 20xa 10% (wlv) sodium metabisulfite solution 20xa
Compound
React with see text water 50x 1 M hydrochloric acid lOOx 2.5 M sodium hydroxide solution 20x see text
lithium aluminum hydride lithium hydride magnesium methanesulfonylchloride methyl disulfide methyltrichlorosilane peracetic acid phosgene in toluene solution phosphorus, red phosphorus, white phosphorus pentoxide potassium potassium t-butoxide
water 20x see text see text 2.5 M sodium hydroxide solution 20x water 20x
potassium hydride potassium permanganate propionyl chloride silicon tetrachloride sodium sodium amide sodium borohydride sodium cyanoborohydride sodium ethoxide sodium hydride sodium hypochlorite sodium methoxide
crushed ice 2Ox water 20x
sodium peroxide
water 20x 2.5 M sodium hydroxide solution 20x see text see text 10% (wlv) sodium metabisulfite solution 20xa 10% (wlv) sodium metabisulfite solution 20xa ethanol 100xb
sodium sulfide strontium sulfuryl chloride
water 20x 10% (wlv) sodium metabisulfite solution 20xa see text see text see text crushed ice and water 20x see text
thionyl chloride thiophenol p-toluenesulfonylchloride triphosgene
ethanol 100xb see text see text see text water 20x see text 10% (w/v) sodium metabisulfite solution 20xa water 20x 10% (wlv) sodium metabisulfite solution 100xa See text water 1OOx 2.5 M sodium hydroxide solution 20x 2.5 M sodium hydroxide solution 20x see text see text see text
'Analytical pmcedure. Add a few drops of lhe readion mixture to an equal volume of 10%(wiv) potassium iodide solution then acidify with a drop of 1 M hydrochloric acid and add a drop of starch salution as an indicator. The deep blue color of the starch-iodinecomplex indicatesthat excess oxidant is present,thus all the compound that is present has not been reduced. %hen the reaction has completely ceased, examine the reaction mixture carefully to make sure that all the metal has dissolved then cautiouslyadd an equal volume of water
for 3 h (benzenesulfonyl chloride) or 24 h (p-toluenesulfonyl chloride), analyze for completeness of destruction as described below, neutralize the reaction mixture, and discard it. B. Add 5 m L of benzenesulfonyl chloride or 5 gofp-bluenesulfonyl chloride b 100 m L of 2.5 M sodium hydmxide solution. Refluxthe reaction mixture for 1h. Cool. Analyze for completeness of destruction as described below, neutralize the reaction mixture, and discard it. T h e following procedure h a s been found useful for t h e analysis of benzenesulfonyl chloride andp-toluenesulfonyl chloride
A 100-pL aliquot of the reaction mixture is neutralized by adding i t to 1m L of a 20 pL/mL solution of acetic acid in methanol. Analvze . bv. reverse phase HPLC using.aeetanitri1e:water 60:40 flowing at 1mWmin thmugh a 250 x 4.6 mm i.d. column ofMierosorb C8 fitted with a 15 x 4.6 mmi.d. guard column of the same material, or a similar system. Use a 20pL injection volume and a UV detectar set at 254 nm. T h e approximate r e t e n t i o n times are 6.5 min for benzenesulfonvl chloride a n d 7.6 min f o r D - toluenesulfonvl chloride. Destruction was >99.98% in each case. Impurit i e s in t h e p - t o l u e n e s u l f o n y l c h l o r i d e m a y give r i s e t o peaks t h a t e l u t e close t o t h e p-toluenesulfonyl chloride Volume 71
Number 11
November 1994
973
peak. This will give rise t o an increase in the limit of detection.
Borane-THF Complex (BH3- THF) B o r a n e - T H F complex r e d u c e s acetone in a slow a n d controlled manner. Add 30 ml.ofn 1 M solution ofhorane-THF in THV la 30 mi. ufnrrtonr with srirnng under nurugen. M e r 5 min add 30 mi. o i w a t r r \Vhm rhr visihle reactron has ucased, add 30 ml. of water and discard the mixture.
Two procedures have b e e n investigated.
A. Do this reaction under nitrogen with provision for venting the considerable amounts of gas that may be generated through a bubbler. Prepare a 10% (vlv) solution of l-butanol in isooctane (2,2,4-trimethylpentane)and add 1,lO-phenanthroline (1 mg1mL) as a n indicator (4). Dry this solution aver 4 A molecular sieve overnight. Stir 15 mL of the l-butanol-isaaetane mixture under nitrogen in a n ice hath and cautiously add 5 mL of a 1.55 M butyllithium solution in hexanes. After 10 min, or when the reaction appears to have stopped, check the color of the mixture. If it is red, indicating t h e presence of excess butyllithium, add mare l-hutanol-isooctane mixture until a yellow calm is produced. When the reaction mixture is yellow, add 10 mL of water. Stir the mixture overnight, separate the layers, and discard them. B. In another technique t h e butyllithium reacts with paly(dimethy1siloxane) to farm lithium silanoate groups that are readily quenched (5).Do this reaction under nitrogen with provision for venting t h e considerable amounts of gas that may he generated through a bubbler. Prepare a mixture of equal volumes of poly(dimethy1siloxane) 200 fluid (5 centistokes, Aldrich 31,766-7 or equivalent) and dry tetrahydrafuran (THF) that contains 2.5 mgImL of 1,lO-phenanthroline as a n indicator (4). Stir 4 mL of the poly(dimethylsilaxsneXTHF mixture under nitrogen and cautiously add 10 mL of a 1.55 M butyllithium solution in hexanes (5).After 3 h, or when the color of the solution has turned from red to vellow. add 25 mL of water If the color dors not change from red to yel1w.v. add mare of the pulydimr~hylsilounne-TIIFmixture. Stlr the mixture tur I h , iepnrarr the layen, and dlicsrd them.
Lithium Aluminum Hydride (LiAIH4) T h r e e procedures w e r e investigated.
k Do this reaction under nitrogen with provision for venting the considerable amounts of gas that may be generated through a bubbler. Use an ice hath. Stir the LiAIH4 in a suitable solvent and for each n gram of L A H 4 present. slowly add n mL of water (6).Add n mL of 15% sodium hydroxide solution and 3n mL of water in succession and stir the mixture vieorouslv for 20 min. Filter the " grmular precipltetc that forms. Separate the organlr and the filtmrc a n d discard them. aqueous lnyeri B. Do this reaction under nitrogen with provision for ventrnz the ~.unsidcrnblramounts of xa!a.l11131 may be gcnrrated through a huhbltr Stlr t h r l.iAIH, in n suirnhle solwnl usinc a n r r t bath. and slowlv ndd 7 ml. of 9Yc ethanol for each gram of L ~ A I HThe.95% ~. ethanol reacts less vigorously than water (7). When the reaction is visihly complete, cautiously add a volume of water equal to t h e initial reaction volume, separate the organic and aqueous layers, and discard them. C. Stir the LiAIH4under nitrogen in a suitable solvent using a n ice hath and slowlv add 11mL of ethvl acetate for each p n m of l.iAIIl.,. ~ t h gacetate l rracrs less v~gorourlythrn wntrr in n slow m d cuntrullrd manner and gcnwaces no h) drogrn X . When the reaction is visibly complete, add a volume of water equal to the initial reactian volume, separate the organic and aqueous layers of the filtrate and discard them.
974
Journal of Chemical Education
Phosgene in Toluene Solution Cautiously add 50 mL uf a 2U'? u v, iolutmn of phoagrnr in tulurw to LOO n>Lof2ULCs o d u n hgdruxde sdutmn and itlr the mixture in a 5UU-ml. flask uwrnrcht. ('over the re;icrmn with aluminum foil to prevent uptakeof atmospheric carbon dioxide. Analyze for completeness of destruction, separate the aqueous and organic layers, and diseard them. The presence of residual phosgene can be determined using the following analytical procedure. Add 100 &Lof the reaction mixture to 2 mL of 2-methoxyethanol and then add 1mL of a 5% (wlv) solution of 4-(4-nitrobenzy1)pyridinein 2-methoxyethanal. Determine the ahsorhance ofthe solution a t 475 nm using an appropriate blank. The limit of detection was 0.01 g/L. Destruction was >99.995%.
Phosphorus, Red Add 1g of red phosphorus to 500 mL of 0.5 M sulfuric acid and add 12 g of potassium hromate while stirring. Stir the reaction mixture until all the phosphorus has dissolved. The reaction time depends on t h e physical characteristics of the phosphorus. Phosphorus in lumps takes 24 h; whereas, powdered ohosohoms reacts in less than 1h. If all the ohos~horus has nut dlaiolred in 24 h, sdd mow pmmaium hromarc \Vhm all rhr phosphorus has d~ssolvcdthe warren is o w r nno lti g of sodium m r r . ~ b ~ a d f i rmwc r ~fnrrcssnn.ihoulo be addrd t u discharge the bromine color. Discard the reaction mixture
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Phosphorus, White Caution: White p h o s p h o r u s is spontaneously flammable in air s o it should be c u t only u n d e r water.
Cut 5 g of white phosphorus under water into pellets that have no dimension greater than 5 mm then add these pellets to 800 mL of 1 M euprie sulfate-solution (7). Allow the reaction mixture to stand in a 2-L beaker in a hood for about a week. Stir occasionally. If one of the larger black pellets is cut under water and no waxy white phosphorus is observed, the reactian is complete. Filter offthe precipitate and, while keeping it wet, add to 500 mL of fresh 5.25% sodium hypochlorite solution (Clorox bleach). Stir this mixture far 1h to oxidize any copper phosphide to copper phosphate. Dispose of the final reactian mixture in an appropriate fashion.
Potassium P o t a s s i u m is the m o s t treacherous of the alkali metals, a n d fires d u r i n e i t s destruction a r e not infreauent. Precautions for its sa&h a n d l i n g h a v e b e e n described (9,101, Add the potassium to dry t-hutyl alcohol (9)a t a rate such that the reaction does not become violent. If the reactian mixs . mme ture herome* wscou+ and the rate ui reacttun 4 1 ) ~ add I-tmyl alcullol. When all the potacilum has h e n added, s r r the reaction mixture until all visible reaction ceases, then examine the reaction mixture carefully for the presence of unreacted metal. If none is found, dilute the mixture with water, neutralize, and discard. Dry t-amyl alcohol may also be used (10).
Whichever alcohol is u s e d it is i m p o r t a n t t o use an anhydrous grade. If necessary, t h e alcohbl should h e dried hefore use. Powdered 3 A molecular sieves h a v e been recomm e n d e d (11)
Potassium Permanganate Take up 5 g of potassium permanganate in 200 mL of 1 M sodium hydroxide solution and add 10 g of sodium metabisulfite. The purple color of the mixture should be discharged; if not, add more sodium metabisulfite. After stirring for 30 min, dilute with 200 mL of water, filter, and diseard it. Test for residual oxidant by adding a few drops of filtrate to a few drops of 10% (wlv) potassium iodide solution. Acidify with 1M hydrochloric acid and add one drop of starch as a n indicator. A deep blue color indicates the presence of oxidant and the reduction procedure should be repeated. Manganese in the filtrate was
determined by atomic absorption spectroscopy at 279.5 nm; 99.7%. The researcher should be aware t h a t when the reaction mixture is evaporated most of the cyanide disappears, presumably throuah the exhaust of t h e aspirator and down the sink. This &ay be important if t h e reaction i s carried out on a large scale. Dissolve each gram of solid NaBH3CN in 10 mL of water. If necessary, dilute reaction mixtures with water so that the concentration of NaBH3CN does not exceed 10%. Stir the NaBH3CN solution and cautiously add 200 mL of sodium hypachlorite solution for each gram of NaBH3CN present. Stir the reaction mixture far 3 h, analyze as described below, and discard it. For each 80 mL of ether extract that may contain cyanide add 200 mL of sodium hypochlorite solution and 150 mL of methanol to produce one phase. Stir the reaction mixture far 3 h, analyze as described below, and discard it. Pass the exhaust gases from the reaction through sodium hypochlorite solution. After allowing the solution to stand for several hours, analyze the sodium hypochlorite solution for cyanide as described below and discard it. I n all cases fresh sodium hypochlorite solution should be used. Before discardina t h e solutions they should be checked to ensure that cyanide is not present (i5)and t h a t they still retain oxidizing power. Add a few drops of the reaction mixture or t r a p solution to a few drops of 10% (wlv) potassium iodide solution. Acidify with 1 M hydrochloric acid and add one drop of starch a s a n indicator. A deep blue color indicates the presence of oxidant.
Sodium Hydride (NaH) and Potassium Hydride (KH) Sodium hydride and potassium hydride generally are supplied as dispersions in mineral oil. For each gram of the hy-
dride dispersion add 25 mL of dry isooctane (2,2,4trimethylpentme) and stir the mixture under nitrogen. For each gram of hydride dispersion slowly add 10 mL of n-butyl alcohol. Ensure that no unreacted material remains on the side of the flask. A h r 30 min. or when the readian amears to have stopped, add 25 mL ofeoid water for each gram df'hydride dispersion. Separate the layers and discard them.
Sulfur-Containing Compounds Sodium hypochlorite oxidizes sodium sulfide to sulfate, carbon disulfide to carbon dioxide and sulfuric acid, thiouhenol to uhenvl " disulfide. and the other sulfur c o m ~ o u n d s to the corresponding sulfonic acids (7). The initial step in t h e oxidation of thiols is the production of t h e corresponding disulfide. Ethyl a n d butyl disulfides are then further oxidized to t h e correspondina sulfonic acids. When butanethiol or butyl disuifide aredegraded it is necessary to add Triton X-100 to solubilize the rather insoluble butvl disulfide and thus allow the reaction to go to completion. Use fresh sodium hypochlorite solution.
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A. Methyl Disulfide, Thiophenol, Sodium Sulfide, a n d Carbon Disulfide Stir 600 mL of a 5.25% sodium hypochlorite solution and 200 mL of 1 M sadium hydmxide solution at roam temperature and add 0.05 males ofmethyl disulfide (4.7 g, 4.5 mL) or 0.05 males of carbon disulfide (3.8 g, 3 mL) or 0.1 mole of thiophenol(11.0 g, 10.25 mL) or 0.1 moles of sodium sulfide (7.8 g) in portions over 1h. Stir the reaction mixture for another hour. If thiopheno1 is being degraded remove solid phenyl disulfide by filtration. Check that the aqueous layer is still capable of oxidation by adding a few drops of the reaction mixture to a few drops of 10% (wlv) potassium iodide solution. Acidify with 1M hydrochloric acid and add one drop of starch as an indicator. A deep blue color indicates the presence of oxidant. Cheek the reaction mixture far completeness~ofdestruction as described below and discard it.
B. Butanethiol, Butyl Disulfide, Ethanethiol, a n d Ethyl Disulfide Stir 600 mL of a 5.25% sodium hypochlorite solution and 200 mL of 1 M sodium hydroxide solution at room temperature and add 3.2 mL of Triton X-100 if butanethiol or butyl disulfide are to be degraded. Add 0.05 moles of ethyl disulfide (6.1 g, 6.1 mL) or 0.05 moles of butyl disulfide (8.9 g, 9.5 mL) or 0.1 mole of ethanethiolf6.2 ... e.. 7.4 mL) or 0.1 males ofhutanethiol(9.0 e. 10.7 ml. in pc,mmsnvrr 1 h. Srlrtht reartwn molturefur 18 h. Check rhar the. aqurour litvrr is itdl ux~dmngby addmg a few drops d the readian mixture to a few dmps of 10%(w/v)potassium iodide solution. Acidify with 1M hydrochloric acid and add one drop of starch as an indicator. Adeep blue color indicates the presence of oxidant. Check the readian mixture for completeness of destruction as described below and discard it. The followina compounds can be determined bv pas c h r ~ m a t o g r a ~ h y u sai n1.8 ~ m x 2-mm i.d. glass c o i u i n packed with 20% Carbowax 20 M on 801100 Snpelcoport (oven temperatures in parentheses): ethanethiol (60 "C), hutanethiol (60 "C), methyl disulfide (60 "C), ethyl disulfide (100 "C), thiophenol(l40 "C), and hutyl disulfide (150 "C). Before analysis, the oxidizing power of the solution should be removed by the addition of sodium metabisulfite. Ethanethiol can be determined by direct injection; the other compounds can be determined after extraction into ether (butanethiol) or 1-butyl methyl ether. Destruction was >99% in each case. When ethanethiol and butanethiol were deeraded no traces of the correspondina disulfides were found in the final reaction mixtures (99.7%. Triphosgene ((CCkOhCO)
Triphosgene is a stable crystalline solid (mp 79-83 "C) that can be used as a more convenient substitute for phosgene (16, 17). Cautiously add 20 mL of 20% sodium hydroxide solution to 2 g of triphosgene and stir the mixture overnight. Cover the
reaction vessel with aluminum foil to prevent uptake of atmospheric carbon dioxide. To test the reaction mixture for completeness of destruction add 1 mL to 9 mL of toluene. Add anhydrous magnesium sulfate, shake, allow to settle, and analyze the toluene solution as detailed above for phosgene. Destruction was >99.7%. Discard the reaction mixture appropriately. Acknowledgment Work was supported by the Division of Safety, NIH through NCI Contract # N01-CO-74102 with PRWDynCorp. The content of this publication does not necessarily reflect the views or policies of the Department of Health and Human Services, nor does mention of trade names, commercial products, or organizations imply endorsement by the U.S.. Government. Literature Cited 1. Lunn,G.;Ssnsane. E. B.DPafrvetion orHaardousChPmicolsinfhPLabomlory, 2nd ed.: Wiley: New Ymk,1994. 2. Lewis, R. J., SI SarB Dongprous Pmpwtie of Industrial Materials, 8th ed.: Van Nostrand %inhold: New York,1992.
3. Bretheriek.L.Bmlho~ickSHondbmkofReacfimChomieolHo2ordp.4thed.:Butter-
6. Suzulu, T. Chom. Eng Naus Februav 11 1991.2. 6. Mieovie,VM.; Mihailovic, M. L. J Org Chsm 1953.
18,119&1200.
7. National Research Council Committee on Hazardous Substances in the Laboratory Pru&nt Practicesfor Disposal of Chemicalsfmm Labomtoria: National Academy Press: Washingian, DC, 1983. 8. Fieser, L. E:Fieser, M. Reogenfsfor Organic Synfhssir: Wiley: New Yo*, 1967:Val.
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