Refractive index brominations

Chakactkrisation of Unsaturatkd Aliphatic Hydrocarbons Unlike the saturated hydrocarbons, unsaturated aliphatic hydrocarbons are soluble in concentrated sulphuric acid and exhibit characteristic reactions with dUute potassium permanganate solution and with bromine. Nevertheless, no satisfactory derivatives have yet been developed for these hydrocarbons, and their characterisation must therefore be based upon a determination of their physical properties (boiling point, density and refractive index). The physical properties of a number of selected unsaturated hydrocarbons are collected in Table 111,11. 

Specifications and Analytical Methods. The commercial aqueous solution is specified as 34% minimum butynediol, as determined by bromination or refractive index. Propargyl alcohol is limited to 0.2% and formaldehyde to 0.7%. 

Numerous methods for the deterrnination of monomer purity, including procedures for the deterrnination of saponification equivalent and bromine number, specific gravity, refractive index, and color, are available from manufacturers (68—70). Concentrations of minor components are deterrnined by iodimetry or colorimetry for HQ or MEHQ, by the Kad-Eisher method for water, and by turbidity measurements for trace amounts of polymer. 

When simple Hquids like naphtha are cracked, it may be possible to determine the feed components by gas chromatography combined with mass spectrometry (gc/ms) (30). However, when gas oil is cracked, complete analysis of the feed may not be possible. Therefore, some simple definitions are used to characterize the feed. When available, paraffins, olefins, naphthenes, and aromatics (PONA) content serves as a key property. When PONA is not available, the Bureau of Mines Correlation Index (BMCI) is used. Other properties like specific gravity, ASTM distillation, viscosity, refractive index. Conradson Carbon, and Bromine Number are also used to characterize the feed. In recent years even nuclear magnetic resonance spectroscopy has been... 

Bromine (128 g., 0.80 mole) is added dropwise to the well-stirred mixture over a period of 40 minutes (Note 4). After all the bromine has been added, the molten mixture is stirred at 80-85° on a steam bath for 1 hour, or until it solidifies if that happens first (Note 5). The complex is added in portions to a well-stirred mixture of 1.3 1. of cracked ice and 100 ml. of concentrated hydrochloric acid in a 2-1. beaker (Note 6). Part of the cold aqueous layer is added to the reaction flask to decompose whatever part of the reaction mixture remains there, and the resulting mixture is added to the beaker. The dark oil that settles out is extracted from the mixture with four 150-ml. portions of ether. The extracts are combined, washed consecutively with 100 ml. of water and 100 ml. of 5% aqueous sodium bicarbonate solution, dried with anhydrous sodium sulfate, and transferred to a short-necked distillation flask. The ether is removed by distillation at atmospheric pressure, and crude 3-bromo-acetophenone is stripped from a few grams of heavy dark residue by distillation at reduced pressure. The colorless distillate is carefully fractionated in a column 20 cm. long and 1.5 cm. in diameter that is filled with Carborundum or Heli-Pak filling. 4 hc combined middle fractions of constant refractive index are taken as 3-l)romoaccto])lu iu)nc weight, 94 -100 g. (70-75%) l).p. 75 76°/0.5 mm. tif 1.57,38 1.5742 m.]). 7 8° (Notes 7 and 8). 

Some diamines carrying very bulky substituents like cardo groups can give colorless polyimides. For example, the bis-9,9-(4-aminophenyl)fluorene (FDA) or brominated and acetylenic FDA derivatives react with 6FDA giving copolymer films62 with low birefringence (low difference between in-plane and out-of-plane refraction index) (Fig. 5.8). A new cardo diamine l,l-bis[4-(4-aminophenoxy)phenyl]cyclododecane (Fig. 5.8) reacts with different aromatic dianhydrides with formation of colorless polyimides.63... 

C. The Rheodyne Model 7010 injection valve, equipped with a 20-pl loop, was switched to injection at the apex of the sample band, as observed on the refractive index detector. The complex kinetics of the production of mono-, di-, and tri-brominated glycols is shown in Figure 14. Optimization of parameters such as the flow rate of acid resulted in a 15% reduction in batch cycle time and eliminated the need for manual analysis and intervention to obtain a desired endpoint composition. 

Tallin (1988) recognized that the refractive index change associated with the OCT/Brj reaction would affect optical resonances of a reacting droplet, so he carried out bromination experiments with levitated droplets using the apparatus shown in Fig. 43. 

Analytical Method Development for TRIS. The detection of brominated compounds of very low volatility such as TRIS posed special analytical problems. Since TRIS has no recognizable chromophore, the detection systems which are commonly used with high performance liquid chromatography (hplc), such as refractive index or short wavelength (<220 nm) uv detectors, are too non-specific to be of much practical use for the analysis of environmental samples. Furthermore, the sensitivities available with these detection methods are generally inadequate. 

The index of refraction of bromine gas at 0° and 760 mm. for the /Mine is 1 001132 according to E. Mascart. The atomic refraction of liquid bromine, according to J. H. Gladstone, is 15 3 and, according to J. W. Briihl, 8 455 by the /t2-formula. The specific refraction, according to A. Haagen, is 01918. The refractive indices of liquid bromine, selected from measurements by C. Riviere, for rays of different wave lengths, at different temp, as indicated in Table I. These data show that the... 

For coloured vapours (bromine) an optical method, depending on measuring the refractive index by an interferometer, has been used. Scott used the Langmuir vibrating quartz-fibre manometer ( 14.VII A) for alkali metals. Fouretier, for Small pressures, used a curved tube containing a dishshaped piston with a small clearance, operating a lever moving a mirror. 

An important technological property of polymers is the glass transition temperature (Tg), that is the temperature at which an amorphous polymer is transformed, in a reversible way, from a viscous or rubbery condition to a hard and relatively brittle one in the vicinity of Tg, a polymer experiences a sudden increase in the rate of molecular motions and, as a result, undergoes a series of conformational transformations. Another important polymer technological property is the refractive index of polymers, whose high values are usually related to highly conjugated, aromatic type, 7i-electron systems that bear heavy elements such as bromine or iodine. 

The commercial aqueous solution is 34% minimum butynediol determined by bromination or refractive index analyzed by GC-FID. 

Many years later Weber indicated that the natural rubber molecule was unsaturated since it reacted with bromine to give a material of empirical formula C5H8Br2. This clearly implied an addition reaction to a double bond. This was borne out by the more accurate and reliable iodine chloride method of Kemp in 1927 and the refractive index technique of Macallum and Whitby in 1924. 

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