Serum caps

Methyl-2-propen-l-ol, purchased from Aldrich Chemical Company, was distilled from anhydrous potassium carbonate. It was added directly to the n-butyllithium solution using a long needle. The checkers quickly replaced the pressure-equalizing dropping funnel with a serum cap to carry out this addition. The funnel was fitted to a small dry flask to prevent the introduction of moisture during the addition period and replaced on the reaction flask immediately afterwards. 

The container was sealed with a serum cap and thermostatted at 25°C. 100 mg aliquots of the solute were added sequentially to the mixture by means of a hypodermic syringe. After each addition, the container was shaken, thermal equilibrium allowed to become established over a period of about 30 minutes and then a 5 pi sample of the solvent taken for GC analysis. Corrections were made for... 

The photolysis vessels were equipped with a gas inlet, serum-capped opening for aliquot removal, and a water-cooled condenser. The irradiated solutions also contained decalin (1.5 x 10 3 M), which was utilized as an internal standard for gc analysis (Varian Aerograph 2400, flame ionization detector,... 

DAS has rivb° 1.6156 and d25° 1.3992 the nuclear magnetic resonance spectrum has a singlet at 8.83 r and an A2B2 pattern at 2.62 r. Although DAS is very oxygen-sensitive, it is readily stored in sample bottles with serum caps. Complexes of many metals have been prepared exceptions include scandium, yttrium, lanthanum, and zinc. 

Intermediate in the CppNbH -Fe(C0)c Reaction. A solution of 0.35 mmol Cp2NbHo in 1 ml CgDg was transferred to a serum-capped NMR tube and cooled to just above freezing. 0.15 ml Fe(C0) was added, the tube was inserted into the XL-100 spectrometer, and a program for kinetic study data acquisition was initiated a set of transients was accumulated for 30 sec and stored data acqui-... 

A. Dibromoearbene addition to (IR)-nopadiene. A 250-raL, three-necked flask is equipped with a mechanical stirrer, nitrogen Inlet, and serum cap. The flask is charged with 26.2 mL (0.30 mol) of bromoform (Note 1), 29.5 g (0.20 mol) of (IR)-nopadlene (Notes 2 and 3), 1.0 g (4.4 mmol) of benzyltriethylammonium chloride (TEBA), 0.8 mL of ethanol, and 20 mL of dichloromethane (Note 4). The suspension Is stirred and cooled In an Ice bath while 100 mL of 50t sodium hydroxide solution Is added over 10 min from a dropping funnel. The reaction mixture Is stirred at room temperature for 24 hr and poured into 250 mL of water. The lower layer Is separated and the... 

B. (lR)-9,9-DimethyttrioyoXo[S.1.1.0 Jdeoa-Z,S-diene. A flame-dried, 3-L flask Is equipped with a large magnetic stirring bar and serum cap and charged with 17.6 g (55.0 mmol) of the dibromide. A total of 2 L of anhydrous... 

Catalytic H2O2 Oxidations. The reactions were carried out in 10-mL tubes equipped with serum cap and a stirring bar. The catalyst, hydrogen peroxide, and substrate were dissolved in of CH3CN. Trimethylacetonitrile was added to the reaction as an internal standard. All reactions were done under argon, each was purged by three freeze-thaw cycles and GC analysis was performed on aliquots withdrawn directly from the reaction mixture. Typically, alkene (1 mmol) was added... 

To a flask which was previously base-washed and dried is added 32 ml of 1.5 M potassium f-butoxide solution in dimethyl sulfoxide. (NOTE The potassium f-butoxide (MSA Research Corp.) is sublimed under 0.1 mm pressure at 155°-160°C, transferred to a brown bottle in a dry nitrogen atmosphere, sealed with a serum cap, dry dimethyl sulfoxide added, and the resulting solution only removed with a syringe.) To the latter solution is added 1.99 gm (0.0046 mole) of the mesitoate ester of < -f/ ra>-2-(4-morpholino)-l, 2-diphenyl-ethanol, the reaction is stirred for 3 hr at room temperature under a nitrogen atmosphere, and the mixture poured in 150 ml of ice-cold water. The resulting solution is extracted with ether, dried, and concentrated to afford 1.16 gm (94%) of crude enamine, m.p. 78°-81°C. The enamine is dissolved in the minimum amount of methanol at temperatures below 50°C, quickly cooled, and then filtered to afford 0.79 gm (65%), m.p. 103°-104°C. 

A. Lithium triethylcarboxide (Solution 1). A thoroughly dried, 1-1., three-necked, round-bottomed flask is fitted with a septum inlet with serum cap, a reflux condenser, and a magnetic stirrer. The flask is purged with and maintained under an atmosphere of dry nitrogen. A solution of 300 ml. of 1.66 M butyllithium (0.50 mole) in hexane (Note 1) is introduced into the flask by syringe (Note 2) and cooled to 0° in an ice bath. Then 58 g. (0.50 mole) of 3-ethyl-3-pentanol (Note 3) is added slowly but constantly by syringe (Note 4). At the end of addition the yellow tint of the butyllithium solution disappears. The alkoxide solution is standardized by hydrolysis of aliquots in water and by titration of the resulting lithium hydroxide with standard acid to a phenol-phthalein end point (Note 5). 

The distilled diene 1 has been obtained with 99% purity by the submitters. The product has the following spectral properties proton magnetic resonance (carbon tetrachloride with benzene as internal standard) S (multiplicity, number of protons) 0.4 (singlet, 9), 4.4 (broad singlet, 2), 5.1 (doublet of multiplets, 1), 5.5 (doublet of doublets, 1), 6.3 (doublet of doublets, 1). The impurities were triethylamine and hexamethyldisiloxane. When stored in a serum-capped flask and removed via syringe, the butadiene is stable for 2 months in a desiccator. 

Alternatively, the butyl lithium solution may be forced into the reaction flask by means of an 18 gauge cannula Inserted through the serum cap. 

Materials. Ethanethiol, obtained from the Eastman Kodak Co., was distilled under nitrogen at atmospheric pressure. The middle fraction collected had a boiling range of less than 0.1°C. and was stored under nitrogen at 0°C. in a vessel fitted with a rubber serum cap. Alkaline solutions were prepared from AnalaR sodium hydroxide (Hopkin and Williams) and deionized distilled water and were stored in steam-cleaned screw-capped polyethylene bottles. 

All optical rotations were measured at the D-line of sodium with a Perkin-Elmer polarimeter (model 141) using a thermostatted 10-cm polarimeter tube dried by a stream of filtered, dried air. Precaution was necessary to exclude water from the solutions in 1,2-dichloroethane and dimethyl sulfoxide. In this connection all glassware was dried at 120 °C and stoppered while hot. All transfers of solvents or solutions were made with syringes using serum caps to exclude moist atmosphere. The compounds which could not be prepared in crystalline condition and recrystallized to purity were obtained from a pure crystalline derivative... 

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