Chloroform freezing

Problem 29 A solution of 100 grams of brucine in 11 chloroform freezes at —64.69 C. What is the molecular weight of brucine ... 

The molecular weight of hrucine is approximately 394. Table 9-3 states that pure chloroform freezes at —63.5° C. 

It forms excellent freezing mixtures with many organic liquids, e.g., with alcohol, — 72° with ether, — 77° and with chloroform, — 77°. 

Although no chemical reaction occurs, measurements of the freezing point and infra-red spectra show that nitric acid forms i i molecular complexes with acetic acid , ether and dioxan. In contrast, the infrared spectrum of nitric acid in chloroform and carbon tetrachloride - is very similar to that of nitric acid vapour, showing that in these cases a close association with the solvent does not occur. 

In the infrared, 2-hydroxycyclobutanone has a carbonyl band at 1780 cm in chloroform solution. Kept in nitrogen-filled screw-capped vials in the freezing compartment of a refrigerator, 2-hydroxyoyolo-butanone slowly but completely solidifies as its dimer. The infrared spectrum of the solid in a KBr disk shows no carbonyl. However, a chloroform solution of the solid does show the characteristic 1780 em band, indicating rapid equilibration with the monomer. 

Five parts of the terpene, 7 of amyl nitrite, and 12 of glacial acetic acid are mixed and cooled with ice and salt, and a mixture of 6 parts of hydrochloric acid and 6 parts of glacial acetic acid added in small quantities at a time. Five parts of alcohol are then added and the mixture allowed to stand in a freezing mixture for a itime. A mass of crystals separates, which consists of the crude nitrosochlorides. This is filtered off and washed with alcohol. When perfectly dry 100 grams of the crystals are digested with 200 c.c. of chloroform for a few moments and at once filtered. The chloroform dissolves a-nitrosochloride, which is precipitated by the addition of excess of methyl alcohol. The crude compound is filtered off, dried and digested with anhydrous ether for... 

C. Isolation and purification of XK-62-2 100 g of the white powder obtained in the above step B are placed to form a thin, uniform layer on the upper part of a 5 cm0X 150 cm column packed with about 3 kg of silica gel advancely suspended in a solvent of chloroform, isopropanol and 17% aqueous ammonia (2 1 1 by volume). Thereafter, elution is carried out with the same solvent at a flow rate of about 250 ml/hour. The eluate is separated in 100 ml portions. The active fraction is subjected to paper chromatography to examine the components eluted. XK-62-2 is eluted in fraction Nos. 53-75 and gentamicin Cja is eluted in fraction Nos. 85-120. The fraction Nos. 53-75 are combined and concentrated under reduced pressure to sufficiently remove the solvent. The concentrate Is then dissolved in a small amount of water. After freeze-drying the solution, about 38 g of a purified preparate of XK-62-2 (free base) is obtained. The preparate has an activity of 950 units/mg. Likewise, fraction Nos. 85-120 are combined and concentrated under reduced pressure to sufficiently remove the solvent. The concentrate is then dissolved in a small amount of water. After freeze-drying the solution, about 50 g of a purified preparate of gentamicin Cja (free base) is obtained. 

NMR analysis, the PHA was extracted from freeze-dried cells. For this purpose, 1.0 g freeze-dried cells were stirred in 200 mL of chloroform for 24 hours at 30°C. The extract was filtered to remove cells debris, and the chloroform was concentrated to a volume of about 15 ruL using rotary evaporator. The concentrated solution was then added drop-wise to 150 luL of rapidly stirred methanol to precipitate the dissolved PHA.The precipitated PHA was then recovered by filtration using a 0.45 pm PTFE membrane and dried overnight at room temperature. The purified PHA was dissolved in deuterated chlorofonn (CDCl ) and subjected to H and NMR analyses. 

Acetylgramine. This substance is active (IV. in mice) at doses of 5 mg per kg and less, making it quite potent. It potentiates response to DMPP (l,l-Dimethyl-4-phenylpiperazinium iodide) and blocks response to acetylcholine and adrenalin. Reflux a mixture of 15 g of 5-aeetylindole or analog (in equimolar amount), 7.55 g of 37% aqueous formaldehyde, 17 g of 25% aqueous di-methylamine, 25 ml of acetic acid, and 250 ml of methanol for 3 hours. Concentrate in vacuo to 20% of original volume, treat with 100 ml of water, wash with chloroform, chill in freezer, and make basic with 20% NaOH. Filter off the crystalline precipitate and wash with cold (near freezing) water to get a little over 17 g of the title product. Recrystallize from benzene to purify. It is unknown to me if this is active orally. 

Poly(ethyl methacrylate) (Cellomer Associates) was vacuum dried at 50 C. The molecular weight (M ) was determined to be 3.3 X 10 from its intrinsic viscosity in ethyl acetate.— Chloroform (spectral grade) and deuterochloroform (MSD Isotopes) were used as received. Prior to sample preparation the solvent was degassed using five freeze-thaw cycles. The solvent was vacuum distilled onto the polymer In a 12 nm NMR tube, and sealed. 

Ovaries (100 g) of the pufferfish Fugu vermicularis porphgreus are extracted with 1% acetic acid in methanol. The extract is concentrated in vacuo and defatted by shaking with chloroform. The defatted extract is treated with activated charcoal. The toxin adsorbed is eluted with 1% acetic acid in 20% ethanol. The eluate is evaporated in vacuo to dryness. The residue is dissolved in a small a-mount of water and adjusted to pH 6 with 1 N NaOH. The toxic solution is applied to an Amberlite IRC-50 column (NH, 2.5 x 45 cm) and developed with 2 L of water, and then 1 L each of 1 and 10% acetic acid. The toxic fractions are freeze-dried, dissolved in 1 mL of water and analyzed by HPLC. 

The method was extended from plants to include soils and waters by Milham ef al. (1970). They point out that nitrate reductase activity in fresh plant samples often causes a rapid decline in nitrate content, so samples collected from remote sites should be frozen in dry ice. A trace of chloroform was used to protect soil and water samples before freezing. We are now more aware of the harmful effects of chloroform inhalation and suggest immediate freezing without preservative and analysis within a few days as a safer alternative - especially with student projects. 

Colorless or yellow oily liquid fumes in air freezes at 2.8°C boils at 140°C with some decomposition bp 85°C at 55 torr density 2.336g/mL at 20°C refractive index 1.601 decomposes in water soluble in hydrochloric acid, chloroform and carbon tetrachloride. 

Colorless liquid commercial grade has a pungent disagreeable odor, in its purest form the odor is sweet and pleasant flammable refractive index 1.6295 density 1.261 g/mL at 20°C boils at 46.3°C freezes at -110.8°C critical temperature 279°C, critical pressure 77.97 atm, critical volume 173 cm3/mol slightly soluble in water, 0.29 g/lOOg at 20°C soluble in alcohol, ether, benzene, chloroform, and oils forms an azeotrope with water (CS2 H2O = 97.2%)... 

Colorless noncombustible liquid chloroform-like odor refractive index 1.4601 density 1.5867g/mL at 20°C boils at 76.8°C freezes at -23°C critical temperature 283.5°C, critical pressure 44.57 atm, critical volume 276 cm /mol practically insoluble in water soluble in alcohol, ether, chloroform and benzene. 

Dark red, fuming liquid reddish yellow vapors musty buring odor density 1.91 g/mL freezes at -96.5°C boils at 117°C reacts with water soluble in chloroform, carhon tetrachloride, benzene, carbon disulfide and nitrobenzene. 

Colorless fuming liquid pungent odor refractive index 1.516 at 14°C density 1.574g/mL at 21°C hods at 76°C freezes at -112°C decomposes in water soluble in benzene, carbon disulfide, ether and chloroform and other halo-genated organic solvents. 

Pale yellow or colorless liquid corrosive refractive index 1.651 at 20°C density 2.42 g/mL at 22°C freezes at 8.5°C boils at 176.4°C decomposes at 176.4°C decomposes in water forming hydrochloric acid and selenious acid soluble in carbon disulfide, carbon tetrachloride, chloroform, benzene, and toluene. 

Silane Colorless gas repulsive odor density 1.44 g/L hquefies at -111.8°C freezes at -185°C decomposes slowly in water insoluble in alcohol, ether, chloroform and sdicon tetrachloride soluble in caustic potash solution. 

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