Carbon hydrogen, analysis

Many compounds that contain carbon and hydrogen also contain nitrogen. Can you find the nitrogen content by carbon-hydrogen analysis, if the nitrogen does not interfere with the combustion reaction If so, explain how. If not, explain why not. 

C2ZD A compound that contains carbon, hydrogen, chlorine, and oxygen is subjected to carbon-hydrogen analysis. Can the mass percent of oxygen in the compound be determined using this method Explain... 

Carbon-Hydrogen. The carbon-hydrogen analysis was performed in a Hallikainen combustion furnace at 1000°C. Ihe. 2 gram sample was combusted in air for 3 minutes and then combusted for 3 minutes in oxygen. Ihe resultant CO2 and H2O were collected using traps specified by ASTM D3178 and determined gravimetrically. 

Figure 2-10 A combustion train used for carbon-hydrogen analysis. The absorbent for water is magnesium perchlorate, Mg(C104)2. Carbon dioxide is absorbed by finely divided sodium hydroxide supported on glass wool. Only a few milligrams of sample is needed for analysis.

This double bond attachment is substantiated by carbon/hydrogen analysis before and after bonding. Furthermore, the basic high stability of the cyclodextrin bonded phases support the idea that a significant number of these types of double bond attachments are, in fact, present. In addition, it is not theoretically impossible that one cyclodextrin molecule could be anchored to the silica by three or more chains, although such attachment bonds have not been experimentally confirmed or identified. These types of phases have been used very successfully in the resolution of the enantiomers of a number of P- blockers (e.g. Propranolol, Atenolol,... 

Figure 2-5 A combustion train used for carbon-hydrogen analysis. The increase in weight of the H2O absorber can be converted into the amount of hydrogen present, while the increase in weight of the...

When a crystalline material has been isolated and demonstrated to be homogeneous by such techniques as paper chromatography or counter-current distribution, the problem of identification arises. This may be approached in the classical manner by measuring the melting point or optical rotation, by carbon-hydrogen analysis, or by other classical procedures. Comparison of the unknown specimen with known compounds and preparation of suitable derivatives often suffice to establish the identity of isolated material. 

C and molecular weight of 1700, exhibits a carbon-hydrogen analysis corresponding to homopolymer. 

Figure 3.6 Combustion train used for carbon-hydrogen analysis. The...

This recrystallised acid is pure in the norm y accepted sense of the word, namely it has a sharp m.p. and gives on analysis excellent values for carbon, hydrogen and nitrogen. If however it is subjected to one-dimensional paper chromatography (p. 53), the presence of traces of unchanged anthranilic acid can be detected, and repeated recrystallisation is necessary to remove these traces. 

For the higher alkoxy groups, standard carbon and hydrogen analysis may be used, although careful sample preparation is required because of the ease of hydrolysis. Quantitative vapor-phase chromatography of alcohol Hberated during hydrolysis may also be used, but care must be taken in this case to ensure that hydrolysis is complete before the estimation is carried out. 

Section 2 of this chapter describes the characterization of carbonaceous materials by powder X-ray diffraction, small-angle-X-ray scattering (SAXS), measurements of surface area, and by the carbon-hydrogen-nitrogen (CHN) test, a chemical analysis of composition. In this section, we also describe the electrochemical methods used to study carbonaceous materials. 

Determine the empirical formula of an organic compound containing carbon, hydrogen, and oxygen by combustion analysis (Example M.4). 

M.12 A compound produced as a by-product in an industrial synthesis of polymers was found to contain carbon, hydrogen, and iodine. A combustion analysis of 1.70 g of the compound produced 1.32 g of C02 and 0.631 g of H20. The mass percentage of iodine in the compound was determined by-converting the iodine in a 0.850-g sample of the compound into 2.31 g of lead(II) iodide. What is the empirical formula of the compound Could the compound also contain oxygen Explain your answer. 

Marino, B.D. and DeNiro, M.J. 1987 Isotopic analysis of archaeobotanicals to reconstruct past climates Effects of activities associated with food preparation on carbon, hydrogen and oxygen isotope ratios of plant cellulose. Journal of Archaeological Science 14 537-548. 

The composition of coal is conveyed by representing its proximate and ultimate analysis. The former implies determination of contents of moisture, volatile matter, fixed carbon, and ash, while the latter implies total carbon, hydrogen, oxygen, nitrogen, sulfur and ash. Here, an account will be provided of the constituents of coal, moisture, volatile matter, ash, fixed carbon, and some miscellaneous components. 

The assumption is made at present that elemental combustion analysis for carbon, hydrogen, and fluorine provides a good approximation to the extent of incorporation of fluoroalkyl residues, i.e. alcohols and ethers. We have ruled out trifluoromethylcarbonyl groups since no evidence is seen for their presence in either the infrared spectra or the 19F-NMR spectra. Thus, our values for percent modification reflect the best fit of the combustion data to an idealized stoichiometry for the product in Equation 1, where (m+n+o) = 100, and the percent modification (% mod.) is given by the expression [100 x (m+o)/(m+n+o)], equivalent to the number of fluoroalkyl residues per one hundred methylenes. An appropriately normalized formula was used to fit the data for polypropylene (sample 10). 

If the sample is pure (this can generally be checked by thin layer chromatography or gas chromatography) then the elemental analysis values for carbon, hydrogen and nitrogen can be used to obtain element ratios, provided that C, H, N and 0 are the only elements present. 

ESCA and AUGER have been carried out on several metals and in all cases the metal has been shown to be in the zerovalent state. Bulk analysis also clearly shows that the metal powders are complex materials containing in many cases significant quantities of carbon, hydrogen, oxygen, halogens, and alkali metal. 

A second process that has a central position in the analysis of the chemical properties of carbenes is their reaction with hydrocarbons. As is the case for alcohols, singlet and triplet carbenes react with hydrocarbons in distinctive ways. It has long been held that very electrophilic singlet carbenes can insert directly into carbon-hydrogen bonds (11) (Kirmse, 1971). On the other hand, triplet carbenes are believed to abstract hydrogen atoms to generate radicals that go on to combine and disproportionate in subsequent steps (12)... 

The determination of the carbon-hydrogen-oxygen content of a compound by combustion analysis involves realizing that all of the carbon has formed carbon dioxide, all of the hydrogen has formed water, and the amount of oxygen present in the original compound must be determined by difference. 

Analysis of griseofulvin, was determined for carbon, hydrogen, and chlorine. The carbon, and hydrogen analysis was performed on a Perkin Elmer Model 240 instrument. Analysis for chlorine was performed by combustion of the sample and coulometric titration using an American Instrument Co. 

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