Normal paraffin solvents

As with conventional emulsions the nature of the oil can affect the behaviour of the system. For pharmaceutical uses, oils used include the refined hydrocarbon oils such as light liquid paraffin and esters of long-chain fatty acids including vegetable oils, for example, ethyl oleate and isopropyl myristate, olive oil and sesame oil. Frankenfeld et al (SO used mixtures of Solvent 100 Neutral (an isoparaffinic, dewaxed oil of high viscosity) and Norpar 13 (a non-viscous, normal paraffinic solvent) to vary the viscosity of the oil phase in attempts to control the transfer of solutes across the oil membrane. 

We first investigated the behavior of mixtures of the normal paraffinic solvents pentane, heptane, and decane with gaseous methane. These mixtures consist of two main UNIFAC groups, methane and the main methyl group CH2 thus, there are only two binary interaction parameters to evaluate. We used the VLE data for the 377 K isotherm of the methane and n-heptane mixture to obtain these parameters for both the HVOS and LCVM models the parameter values are reported in Table 5.3.1. We then estimated the VLE at all other temperatures of the three mixtures. The results... 

Amount of asphalt precipitation increases with decrease in molecular weight of normal paraffinic solvents. 

Hayduk W, Cheng SC (1970) Solubilities of ethane and other gases in normal paraffin solvents. Can J Chem Eng 48 93-99... 

Exxon Chemical and Shell Chemical are the two largest suppliers of aliphatic and aromatic hydrocarbons. Exxon offers catalytically synthesized isoparaffi-nic solvents under the tradename of Isopar, a family of dearomatized aliphatic hydrocarbon solvents under the trademark of Exxsol, while the tradename Norpar signifies three grades of high content normal paraffinic solvents with... 

The normal paraffinic solvent blends sold by Exxon under the tradename of Norpar (Table 15.4) are also used in industrial and institutional cleaners and degreasing formulations. This series of solvents are similar in many respects to the Isopar and Exxsol solvent blends also used in cleaners and degreasers. The Norpar 13 and 15 can be formulated into noncombustible cleaners. The Norpar solvents may be used in certain applications involving incidental food contact under several FDA regulations. Exxon Chemical can supply details about the regulated applications. 

Highly pure / -hexane can be produced by adsorption on molecular sieves (qv) (see Adsorption, liquid separation) (43). The pores admit normal paraffins but exclude isoparaffins, cycloparaffins, and aromatics. The normal paraffins are recovered by changing the temperature and/or pressure of the system or by elution with a Hquid that can be easily separated from / -hexane by distillation. Other than ben2ene, commercial hexanes also may contain small concentrations of olefins (qv) and compounds of sulfur, oxygen, and chlorine. These compounds caimot be tolerated in some chemical and solvent appHcations. In such cases, the commercial hexanes must be purified by hydrogenation. 

Chemistry. Chemical separation is achieved by countercurrent Hquid— Hquid extraction and involves the mass transfer of solutes between an aqueous phase and an immiscible organic phase. In the PUREX process, the organic phase is typically a mixture of 30% by volume tri- -butyl phosphate (solvent) and a normal paraffin hydrocarbon (diluent). The latter is typically dodecane or a high grade kerosene (20). A number of other solvent or diluent systems have been investigated, but none has proved to be a substantial improvement (21). 

Dilute Binary Hydrocarbon Mixtures Hayduk-Minhas presented an accurate correlation for normal paraffin mixtures that was developed from 58 data points consisting or solutes from C5 to C32 and solvents from C5 to Cig. The average error was 3.4 percent for the 58 mixtures. 

Molecular sieves are an adsorbent that is produced by the dehydration of naturally occurring or synthetic zeolites (crystalline alkali-metal aluminosilicates). The dehydration leaves inter-crystalline cavities into which normal paraffin molecules are selectively retained and other molecules are excluded. This process is used to remove normal paraffins from gasoline fuels for improved combustion. Molecular sieves are used to manufacture high-purity solvents. 

Duosol Process. The Duosol process developed by the Max B. Miller Co. (28) is an outstanding example of commercial adoption of a double solvent extraction process. Patents (27) for this process date from May 1933 and cover numerous aspects of the problem including a variety of paraffinic solvents (ethane, propane, butane, petroleum ether) and naphthenic solvents (wood tar acids, cresols, creosote, and phenol). Present commercial application utilizes propane and Selecto (a mixture of phenol and cresylic acid, normally ranging in composition from 20 to 80% phenol). 

Absorption and fluorescence spectra of aromatic hydrocarbons are not greatly affected by change of solvent, except for small solvent shifts. At low temperatures the vibrational structure of the bands sharpens up, and some peculiar solvent effects have been noted. When frozen in solution of normal paraffins coronene shows doubling of some of its vibrational bands, and the separation of the components varies with the number of carbon atoms in the solvent molecule chain. The most probable cause is some size-relationship factor between solvent and solute molecules (7). 

Hydrolytic and radiolytic degradation of TAP solution in normal paraffinic hydrocarbon (NPH) in the presence of nitric acid was investigated. Physicochemical properties such as density, viscosity, and phase-disengagement time (PDT) were measured for undegraded and degraded solutions (197). The variations in these parameters were not very different from those obtained with degraded TBP. Thus, the hydro-dynamic problems expected during the solvent-extraction process with TAP would be similar to those encountered with TBP/NPH system. The influence of chemical... 

In fact, the first description of such a scheme, involving the application of SFE to spent nuclear fuel reprocessing, appeared shortly after publication of these results. Specifically, Smart et al.43 outlined two possible approaches to SC-C02-based reprocessing. In the first, dubbed the wet SF-PUREX process, SC-C02 merely serves as a replacement for the organic solvent (i.e., a normal paraffinic hydrocarbon) used in... 

In 1951, Titov and Shchitov [103] when examining the action of nitric anhydride on normal paraffins and cycloparaffins, found that in the presence of an inert solvent the reaction already started at 0°C, with the evolution of heat. Nitric acid esters were formed in the reaction which, according to the authors, proceeded through the following stages ... 

Finally we should add a word about the classically famous data of Meyer and van der Wyk (179 ) on the intrinsic viscosities of pure normal paraffin hydrocarbons in carbon tetrachloride. If these data are included in our plot based on Eq. (58), the point for CS4H70 falls close to the converging lines for high-molecular-weight polyethylenes in several solvents, but the points for lower hydrocarbons, down to C17H36, fall well below. In our opinion this does not argue for a still lower value of A than the one we have chosen, but is better interpreted as evidence for an end effect, such as is also to be found in certain condensation polymers. [See Section III C and IIID where this effect is considered in more detail.]... 

Americium and plutonium were separated by one cycle of solvent extraction using 30% TBP in a normal paraffin hydrocarbon diluent. Plutonium was extracted while americium was diverted to the aqueous waste stream (2AW). 

Materials suitable for the production of lubricating oils are comprised principally of hydrocarbons containing from 25 to 40 carbon atoms per molecule, whereas residual stocks may contain hydrocarbons with 50-60 or more (up to 80) carbon atoms per molecule. The composition of a lubricating oil may be substantially different from that of the lubricant fraction from which it was derived, because wax (normal paraffins) is removed by distillation or refining by solvent extraction and adsorption preferentially... 

Volatile is relative. It may mean (1) any compound which will purge, (2) any compound which will elute before the solvent peak (usually those solvent removal stage. Waxes of petroleum origin consist primarily of normal paraffins. Waxes of plant origin consist of esters of unsaturated fatty acids. 

Table II shows the H NMR data on 0.1 M iso-HMTT and 0.1M iso-HMTT LiBr in CH2C12 and in benzene. Of primary interest is the last entry in the table, AChei, the chelation shift for iso-HMTT LiBr relative to free iso-HMTT in each of the two solvents. The values of Achei in CH2C12 are analogous to what is observed for lithium alkyl systems such as TMED LiBu in paraffinic solvents. The small 0.1 ppm) down-field shift of the N-CH3 protons accompanied by essentially no shift of the N-CH2- protons is typical for lithium chelates in non-aromatic solvents and is what we have referred to as a normal chelation shift. Observation of this normal AChei is evidence that iso-HMTT LiBr does exist as the chelate in CH2C12.

FIGURE 6.7 Normal and non-normal paraffin distributions in a waxy 100N feed to dewaxing. Source R. J. Taylor and A. J. McCormack, Study of Solvent and Catalytic Lube Oil Dewaxing by Analysis of Feedstocks and Products, Ind. Eng. Chem. Res., vol. 31, pp. 1731-1738 (1992). With permission. 

FIGURE 6.8 Normal and non-normal paraffin distributions in wax obtained by solvent dewaxing a waxy 100N. 

---