Chloroform decomposition temperature

When the nitrogen atom of a pyridine is sufficiently nucleophilic, for example 3-cyano- (pK 1.45) but not 3-bromopyridine (pATa 0.9), attack occurs at the triple bond of the ester.238 The reaction can be very vigorous and, if carried out at - 60° in ether, pyridine itself appears to yield the zwitterion 1 which can be trapped by carbon dioxide. No direct physical evidence has been obtained for 1 and the first product detectable by low-temperature NMR measurements is the 9a//-quinolizine 5.239 Both geometrical forms of the betaine (2) have been isolated, and, at 0° in chloroform, decomposition to carbon dioxide, detected by its absorption at 2335 cm-1, and a red tar, occur rapidly. Treatment of the betaines with aqueous perchloric acid at its freezing point, however,... 

The two crystal forms have essentially the same solubility in water and essentially the same decomposition temperature. Form B is the more usually observed form. No solvates or polymorphic modifications of dexamethasone were reported by Mesley for dexamethasone crystallized from chloroform, acetone and ethanol using X-ray diffraction patterns and solid state I.R. spectra to evaluate samples. 

Stereocomplex Formation in Bulk. DSC measurements were carried out by mixing appropriate chloroform solutions of the block copolymers and I-PMMA followed by drying in a vacuum oven at 50°C for 24 hours prior to annealing at various temperatures. DSC thermograms of mixtures of I-PMMA (124,000) with S-PMMA (6800) and with AB-PDMS-S-PMMA (4000-6800) are shown in Figure 4. A single decomposition temperature of about 170° is observed in both cases and the AH values for the homo- and copolymer are also seen to be quite similar. This indicates that, at least in this case, the PDMS block does not appear to hinder stereocomplex... 

Ben2onitri1e [100-47-0] C H CN, is a colorless Hquid with a characteristic almondlike odor. Its physical properties are Hsted in Table 10. It is miscible with acetone, ben2ene, chloroform, ethyl acetate, ethylene chloride, and other common organic solvents but is immiscible with water at ambient temperatures and soluble to ca 1 wt% at 100°C. It distills at atmospheric pressure without decomposition, but slowly discolors in the presence of light. 

Aqueous sodium thiosulfate solutions ate neutral. Under neutral or slightly acidic conditions, decomposition produces sulfite and sulfur. In the presence of air, alkaline solutions decompose to sulfate and sulfide. Dilute solutions can be stabilized by small amounts of sodium sulfite, sodium carbonate, or caustic, and by storage at low temperatures away from air and light. Oxidation is inhibited by Hgl2 (10 Ppm) amyl alcohol (1%), chloroform (0.1%), borax (0.05%), or sodium benzoate (0.1%). 

Unreacted phosgene is removed from the cmde chloroformates by vacuum stripping or gas purging. Chloroformates of lower primary alcohols are distillable however, heavy-metal contamination should be avoided. As stated earlier, chloroformates generating a stable carbonium ion on decomposition, ie, secondary or tertiary chloroformates or henzylic chloroformates, are especially unstable in the presence of heavy metals and more specifically Lewis acids and, hence, should be distilled at as low a temperature and high vacuum as possible. 

Chloroform and water at 0°C form six-sided crystals of a hydrate, CHCl I8H2O [67922-19-41which decompose at 1.6°C. Chloroform does not decompose appreciably when in prolonged contact with water at ordinary temperature and in the absence of air. However, on prolonged heating with water at 225°C, decomposition to formic acid, carbon monoxide, and hydrogen chloride occurs. A similar hydrolysis takes place when chloroform is decomposed at elevated temperature by potassium hydroxide. 

To a stirred solution of 5.7 g (0.02 m) of 4-benzyloxy-2-ureidoacetophenone in 100 ml of chloroform is added 3.2 g (0.02 m) of bromine. The mixture is stirred at room temperature for about 45 minutes and the solution is concentrated in vacuo at 25°-30°C. The amorphous residue (hydrobromide selt of 4-benzyloxy-a-bromo-3-ureidoacetophenone) is dissolved in 80 ml of acetonitrile and 98 g (0.06 m) of N-benzyl-N-t-butylamine is added. The mixture is stirred and refluxed for 1.5 hours, then it is cooled toOt in an ice bath. Crystalline N-benzyl-N-t-butylamine hydrobromide is filtered. The filtrate is acidified with ethereal hydrogen chloride. The semicrystalline product is filtered after diluting the mixture with a large excess of ether. Trituration of the product with 60 ml of cold ethanol gives 4-banzyloxy-Of-( N-benzyl-N-t-butylamino)-3-ureidoacetophenone hydrochloride, MP 200°-221°C (decomposition). 

Evaporation of a chloroform solution of benzoylhydroperoxide under reduced pressure yields a paste containing 20-30 per cent of hydroperoxide. On further evaporation this decomposes into benzoic acid. A chloroform solution of benzoylhydroperoxide when carefully dried over anhydrous sodium sulfate at o° may be kept exposed to light at room temperature for a number of days without appreciable decomposition. In order to obtain benzoylhydroperoxide free from the reagents used in its preparation, it is necessary to extract the product with chloroform, such extraction resulting in a loss of about 10 per cent,... 

Water can be added to the mother liquor, and the mixture extracted with chloroform to increase the diazide recovery to nearly quantitative (95-98%). During the course of any purification method that might be employed the diazide should not be heated above 50°, since decomposition occurs quite noticeably at that temperature. It is best to store the pure product below —5° in the dark, since it undergoes a facile photochemical rearrangement to the cyclopentene-dione. 

Although this reaction can be carried out at higher temperatures, the yields are reduced, probably owing to loss of the volatile methyl chloroformate, b.p. 71°, and/or decomposition of the product. For example, the yields of trichloromethyl chloroformate are ca. 75% and 55% when the chlorination is carried out at 50-55° and 85-90°, respectively. 

The explosive decomposition of the solid has been studied in detail [6], The effect of moisture upon ignitibility and explosive behaviour under confinement was studied. A moisture content of 3% allowed slow burning only, and at 5% ignition did not occur [7], Thermal instability was studied using a pressure vessel test, ignition delay time, TGA and DSC, and decomposition products were identified [8], The presence of acyl chlorides renders dibenzoyl peroxide impact-sensitive [9], There is a further report of a violent explosion during purification of the peroxide by Soxhlet extraction with hot chloroform [10], Residual traces of the peroxide in a polythene feed pipe exploded when it was cut with a handsaw [11]. The heat of decomposition has been determined as 1.39 kJ/g. The recently calculated value of 69° C for critical ignition temperature coincides with that previously recorded. 

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