Quantitation with

Schultz K A and Seebauer E G 1992 Surface diffusion of Sb on Ge(111) monitored quantitatively with optical second harmonic microscopy J. Chem. Phys. 97 6958-67... 

Evidence from the viscosities, densities, refractive indices and measurements of the vapour pressure of these mixtures also supports the above conclusions. Acetyl nitrate has been prepared from a mixture of acetic anhydride and dinitrogen pentoxide, and characterised, showing that the equilibria discussed do lead to the formation of that compound. The initial reaction between nitric acid and acetic anhydride is rapid at room temperature nitric acid (0-05 mol 1 ) is reported to be converted into acetyl nitrate with a half-life of about i minute. This observation is consistent with the results of some preparative experiments, in which it was found that nitric acid could be precipitated quantitatively with urea from solutions of it in acetic anhydride at —10 °C, whereas similar solutions prepared at room temperature and cooled rapidly to — 10 °C yielded only a part of their nitric acid ( 5.3.2). The following equilibrium has been investigated in detail ... 

Coulometric methods of analysis are based on an exhaustive electrolysis of the analyte. By exhaustive we mean that the analyte is quantitatively oxidized or reduced at the working electrode or reacts quantitatively with a reagent generated at the working electrode. There are two forms of coulometry controlled-potential coulometry, in which a constant potential is applied to the electrochemical cell, and controlled-current coulometry, in which a constant current is passed through the electrochemical cell. 

Since the current due to the oxidation of H3O+ does not contribute to the oxidation of Fe +, the current efficiency of the analysis is less than 100%. To maintain a 100% current efficiency the products of any competing oxidation reactions must react both rapidly and quantitatively with the remaining Fe +. This may be accomplished, for example, by adding an excess of Ce + to the analytical solution (Figure 11.24b). When the potential of the working electrode shifts to a more positive potential, the first species to be oxidized is Ce +. 

Hydroiodic acid reacts quantitatively with iodic acid to give iodine ... 

The first-stage catalysts for the oxidation to methacrolein are based on complex mixed metal oxides of molybdenum, bismuth, and iron, often with the addition of cobalt, nickel, antimony, tungsten, and an alkaU metal. Process optimization continues to be in the form of incremental improvements in catalyst yield and lifetime. Typically, a dilute stream, 5—10% of isobutylene tert-huty alcohol) in steam (10%) and air, is passed over the catalyst at 300—420°C. Conversion is often nearly quantitative, with selectivities to methacrolein ranging from 85% to better than 95% (114—118). Often there is accompanying selectivity to methacrylic acid of an additional 2—5%. A patent by Mitsui Toatsu Chemicals reports selectivity to methacrolein of better than 97% at conversions of 98.7% for a yield of methacrolein of nearly 96% (119). 

With sodium azide, salts of secondary nitroparaffins rearrange to N-substituted amides (29). With SO2, primary or secondary nitroparaffins give imidodisulfonic acid salts (30). Potassium nitroform reacts quantitatively with nitryl chloride in ether to form tetranitromethane (31). 

Quantitative Analysis. OxaUc acid is precipitated as calcium oxalate from a solution containing oxaUc acid, and the calcium oxalate obtained is then weighed. If there are no organic substances other than oxaUc acid present, oxaUc acid can be titrated quantitatively with potassium permanganate. 

A double end point, acid—base titration can be used to determine both sodium hydrosulfide and sodium sulfide content. Standardized hydrochloric acid is the titrant thymolphthalein and bromophenol blue are the indicators. Other bases having ionization constants in the ranges of the indicators used interfere with the analysis. Sodium thiosulfate and sodium thiocarbonate interfere quantitatively with the accuracy of the results. Detailed procedures to analyze sodium sulfide, sodium hydro sulfide, and sodium tetrasulfide are available (1). 

Nitrous acid reacts very rapidly and quantitatively with sulfamic acid ... 

Hypochlorous acid reacts very rapidly and quantitatively with a slight excess of free ammonia forming monochloramine, NH2CI, which reacts at a slower rate with additional HOCl forming dichloramine, NHCI2. Trichloramine is formed when three moles of HOCl are added per mole of ammonia between pH 3—4 (100). Hypochlorous acid in the form of chlorine or hypochlorite is used in water treatments to oxidize ammonia by the process of break-point chlorination, which is based on formation of unstable dichloramine. The instabiHty of NHCI2 is caused by presence of HOCl and NCl (101,102). The reaction is most rapid at a pH of about 7.5 (103). Other nitrogen compounds such as urea, creatinine, and amino acids are also oxidized by hypochlorous acid, but at slower rates. Unstable iV-chloro compounds are intermediates in deammination of amino acids (104,105). 

First order decomposition was established for dimethyldiazirine (215) and ethylmethyl-diazirine (216). The activation energy is 139 kJ moF for (215) the half life at 100 °C is 97 h. On decomposition of (216) the products formed and their respective yields are as indicated. The products correspond qualitatively and quantitatively with the results of thermal decomposition of 2-diazobutane formed in situ in aprotic solvents. Analogous comparisons of decomposition products of diethyldiazirine, isopropylmethyldiazirine, n-butyl- and t-butyl-diazirine agree equally well 66TL1733). 

Figure 23-36 shows a computer calculation with these specific rates, but which does not agree quantitatively with the figure shown by Swern. The time scales appear to be different, but both predict a peak in the amount of oleic acid and rapid disappearance of the first two acids. 

BBT solution on unmodified sorbents of different nature was studied. Silica gel Merck 60 (SG) was chosen for further investigations. BBT immobilization on SG was realized by adsoi ption from chloroform-hexane solution (1 10) in batch mode. The isotherm of BBT adsoi ption can be referred to H3-type. Interaction of Co(II), Cu(II), Cd(II), Ni(II), Zn(II) ions with immobilized BBT has been studied in batch mode as a function of pH of solution, time of phase contact and concentration of metals in solution. In the presence of sodium citrate absorbance (at X = 620 nm) of immobilized BBT grows with the increase of Cd(II) concentration in solution. No interference was observed from Zn(II), Pb(II), Cu(II), Ni(II), Co(II) and macrocomponents of natural waters. This was assumed as a basis of soi ption-spectroscopic and visual test determination of Cd(II). Heavy metals eluted from BBT-SG easily and quantitatively with a small volume of HNO -ethanol mixture. This became a basis of soi ption-atomic-absoi ption determination of the total concentration of heavy metals in natural objects. 

Di-tcrt-butyl dichlorosilane (DTBCI2) [18395-90-9] M 213.2, m -15°, b 190°/729mm, 195-197°/atm, d 1.01. Purified by fractional distn. It is a colourless liquid with a pleasant odour and does not fume in moist air, but does not titrate quantitatively with excess of dil alkali. [7 Am Chem Soc 70 2877 1948.]... 

If very pure amine is desired the product described above is dissolved with 1.04 parts of crystalline oxalic acid in eight parts of hot water. After clarification with Norite, the filtered solution on cooling deposits crystals of the acid oxalate. About 5 g. of the salt remains in each 100 cc. of the mother liquor most of this can be obtained by evaporation and further crystallization. The amine is liberated from the pure oxalate with potassium hydroxide, distilled with steam, and purified as described above. When a known amount of amine is desired in water solution (as for optical resolution) a weighed amount of the (anhydrous) oxalate is decomposed and the amine is distilled quantitatively with steam. 

When the amine is to be us d in water solution a weighed amount of the pure salt may be decomposed with alkali, the base distilled quantitatively with steam, and the entire distillate used. 

Yes, semiquantitative without standards quantitative with standards. Not a trace element method. 

GDMS is slowly replacing SSMS because of its increased quantitative accuracy and improved detection limits. Like SNMS and SALI, GDMS is semiquantitative without standards ( a factor of 3) and quantitative with standards ( 20%) because sputtering and ionizadon are decoupled. GDMS is often used to measure impuri-des in metals and other materials which are eventually used to form thin films in other materials applications. 

Allene itself is not a good dienophile, its reaction with cyclopentadiene requires temperatures of >200 °C and gives a 49% yield [90] Fluoraallene and 1,1-difluoroaIIene are much more reactive dienophiles, the latter reacting instantly and quantitatively at -20 °C [91, 92], and the former taking 4 days to react quantitatively with cyclopentadiene at 0 °C [25, 27, 93] (equation 78)... 

Sulfur diimides react readily and quantitatively with organolithium reagents at the sulfur centre to produce lithium sulfmimidinates of the type Li[RS(NR )2] x- ° The lithium derivatives may be hydrolyzed by... 

The observed solvent effect can be expressed quantitatively with the aid of the Leffler-Grunwald operator 5m introduced in Chapter 7. For rate constant k measured in medium M we have, from transition state theory, k = (kT//i)exp ( —AGm// T) and similarly for rate constant ko measured in a reference solvent. Combining these two expressions gives... 

Reacidification reprecipitates AS2S3 quantitatively. With alkali metal or ammonium polysulfides thioarsenates are formed which are virtually insoluble even in hot cone HCl ... 

Similarly, indole itself could be converted by 2-methylsulfanyl-l,3-dithiolium iodide to its 3-dithiolium derivative, which gave 27 quantitatively with DBU. However, treatment of indoles, which bear the benzo-dithiolium moiety in the 2-position with tertiary amines, resulted in a black reaction mixture. All attempts to isolate the o-quinoid compound 28 failed (Scheme 7). 

Strong acids react nearly quantitatively with DTDAFs of type 47 under reformation of their starting material, the A-alkylbenzothiazolium salts (64BSF2857). Using the violet-colored derivative 130, this protonation became visible (81FICA648) (Scheme 52). 

The reaction of 5-methoxy-2(5//)-furanone 168 with amines was also studied (89T6799). The conjugated addition of ethanolamine to the furanone 168 gave the racemic amino lactone 275 (R = CH2CH20H). Similarly, piperazine reacted with two equivalents of 168 to provide the diadduct 276 as a single diastereomer (no traces of the other isomer were detected). With tryptamine, the reaction was nearly quantitative with the the formation the tran -adduct 277 (R = tryptophanyl) (Scheme 72) (89T6799). 

Evidence for that stereochemical course comes from the rearrangement of meso-3,4-dimethylhexa-1,5-diene 4, which yields the E.Z-configured diene 5 almost quantitatively. With a transition state of boatlike geometry, a Z,Z- or E,E-configured product would be formed." ... 

To obtain reliable, accurate, and reproducible methods for quantitative estimation of deoxy sugars, certain conditions must be fulfilled. Thus, it is necessary that the chromogen be formed quantitatively from the sugar. The chromogen must then react quantitatively with the compound used for color formation, and lastly, the dye, once formed, should be stable and have a well defined molar extinction coefficient. In methods in which all of these conditions are not or cannot be fulfilled, recourse must be had to simultaneous determinations with suitable standard substances, a requirement not always easy to fulfil. 

If the fusion temperature is about 300°, the yield of platinum oxide is very low, at higher temperatures the yield increases, and at temperatures of 450° and higher it is practically quantitative. With a proper fusion a slightly lower yield than quantitative is generally not due to non-precipitation of the platinum but to loss by spattering and to deposition of a small amount on the casserole. 

The term titrimetric analysis refers to quantitative chemical analysis carried out by determining the volume of a solution of accurately known concentration which is required to react quantitatively with a measured volume of a solution of the substance to be determined. The solution of accurately known strength is called the standard solution, see Section 10.3. The weight of the substance to be determined is calculated from the volume of the standard solution used and the chemical equation and relative molecular masses of the reacting compounds. 

Various substances cannot be oxidised directly with potassium bromate, but react quantitatively with an excess of bromine. Acid solutions of bromine of exactly known concentration are readily obtainable from a standard potassium bromate solution by adding acid and an excess of bromide ... 

Discussion. A number of phenols can be substituted rapidly and quantitatively with bromine produced from bromate and bromide23 in acid solution (Section 10.131). The determination involves treating phenol (Note 1) with an... 

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