Cyclohexane-soluble fraction

CYCLOHEXANE EXTRACTION. A 5-6g portion of the product was cut into small pieces and stirred in 250 ml cyclohexane at room temperature for 60 hr. The insoluble fraction was separated by filtering the solution through cheesecloth. The cyclohexane-soluble fraction was recovered by distilling the solvent in vacuo and the polymer was dried in vacuo at 40 C for 24 hr. 

Source Apportionment Models for the Cyclohexane-Soluble Fraction of Respirable Suspended Particulate Matter. Stepwise multiple regression analysis was used to determine the coefficients of the source tracers for the models proposed for CYC in equations (7)-(9). These models are shown in Table IV. As expected from the factor analyses, the coefficient for V, accounting for the greatest proportion of the variance of CYC, was fitted first into the equation. Equation (14) was the simplest and the F value was slightly higher than for equations (15) and (16). In addition, as will be discussed later in this paper, the coefficient for PB was in reasonable agreement with the ratio of CYC /PB for samples collected in the Allegheny Tunnel. 

HVL-P) was extracted with two solvents once with ethanol, and once with cyclohexane at room temperature and a solvent/sample ratio of 10. HVL-P, the ethanol-soluble fraction (ES) of HVL, and cyclohexane-soluble fraction (CyS) of HVL-P were distilled at temperatures ranging from 250° to 365°C under a variable vacuum down to 2 torr. Distillable fractions were designated "light , "middle" and "heavy" with the undistilled part termed "resid". The "light" fraction was yellowish and fluid up to -5°C the "middle" fraction was reddish and fluid at room temperature but solidified at lower temperatures, while the "heavy" fraction was red, and the "resid" fraction was black. 

Comparison of Distillation Products from HVL-P and its Cyclohexane Soluble Fraction... 

One of the most salient features of the detailed MS data summarized in Tables II-V is the similarity of the components determined in the light asphaltenes to those generally found in the cyclohexane-soluble fractions. Asphaltenes are simply more polar than the cyclohexane solubles, but less polar than the polar fraction separated from the cyclohexane-soluble fraction. This is attributable to the fact that asphaltenes contain significant amounts of neutral components. The overall amount of polar components is much higher in asphaltenes than in the cyclohexane solubles, and this is the factor that is... 

Figure 21.13 Evolution of the SEC chromatogram of the cyclohexane soluble fraction of cyclic PS comb (sample C-2-100) recovered at decreasing temperatures in the range 20-18 °C. (Reprinted with permission from M. Schappacher and A. Deffieux, Atomic force microscopy imaging and dilute solution properties of cyclic and linear polystyrene combs, Journal of the American Chemical Society, 130, 14684-14689, 2008. 2008 American Chemical Society.)...

The reaction of EPR with dicumyl peroxide (DCP) at 180°C yielded a fraction insoluble in cyclohexane at 22 C. The presence of maleic anhydride (MAH) in the EPR-DCP reaction mixture increased the amount of cyclohexane-insoluble gel. However, the gel concentration decreased as the DCP concentration increased. The MAH content of the soluble polymer increased when either the MAH or the DCP concentration increased. The molecular weight of the soluble polymer increased with increasing MAH concentration and decreased with increasing DCP concentration in the reaction mixture. The products from the EPR-DCP and EPR-MAH-DCP reactions were soluble in refluxing xylene and were fractionated by precipitation with acetone. The presence of stearamide in the EPR-MAH-DCP reaction increased the amount and the molecular weight of the cyclohexane-soluble polymer. 

The presence of 0.25-0.5 wt-% DCP at 180°C resulted in the formation of about 20% of a cyclohexane-insoluble fraction. The presence of 5 wt-% MAH (based on EPR) increased the amount of cyclohexane—insoluble gel, whose concentration decreased from 65% to 27% as the DCP content increased from 0.25 to 1.0 wt-% (based on EPR), respectively. The cyclohexane-soluble polymer contained about 1 wt-%... 

Exposure limits No individual standards have been set. As a constituent in coal tar pitch volatiles, the following exposure limits have been established (mg/m ) NIOSH REL TWA 0.1 (cyclohexane-extractable fraction), IDLH 80 OSHA PEL TWA 0.2 (benzene-soluble fraction) ACGIH TLV TWA0.2 (benzene solubles). 

Trace metal, sulfate and organic species in RSP samples are indicated with an superscript. The symbols CYC, DCM and ACE have been used for the cyclohexane-, dichloromethane-, and acetone-soluble fractions of the RSP samples, respectively. 

The data in Table HIlikewise show a major difference between solvent extraction and distillation. Cyclohexane soluble material, CyS, had a wide spread in molecular weight as did HVL-P itself. Cyclohexane dissolved all of the Light and Middle fractions, and about 50% of the Heavy fraction and Resid in HVL-P. Thus, cyclohexane extraction is not as effective as distillation... 

Separations. The asphaltene fractions were obtained by solvent extraction with benzene and subsequent precipitation with cyclohexane. The cyclo-hexane-soluble fractions were separated into saturate, aromatic, and polar aromatic fractions by the clay-gel technique, ASTM D-2007 (modified). This separation is also applicable to asphaltenes. 

The presence of hydrocarbons and of low molecular weight heterocompounds identical to those found in the cyclohexane- or pentane-soluble fractions of coal liquids was rather unexpected. However, neutral hydrocarbons have been identified in other coal asphaltenes (10), and more recently,... 

Fig. 7-19. Distribution of water-soluble (ws), organic solvent-soluble (os), and insoluble mass fractions associated with the rural continental aerosol at Deuselbach, West Germany, according to measurements of Winkler (1974). The organic fraction comprises material soluble in cyclohexane, ether, acetone, and part of the methanol-soluble fraction. The uncertainty range assumes that 0-40% of the methanol-soluble fraction contains organic compounds, and the remainder is due to inorganic salts. The water-soluble fraction of organics averages about 0.66 for all size ranges combined.

EXPOSURE GUIDELINES ACGIH TLV (phenanthrene, cyclohexane extractable fraction) 1030 mg/m ACGIH TLV (coal tar pitch volatiles-benzene soluble) 0.2 mg/m NIOSH REL (coal tar pitch volatiles, benzo(a)pyrene) 0.1 mg/m. ... 

Our analytical procedure consists of stepwise acetone extraction followed by cyclohexane. Subsequently, the acetone-soluble fraction is partioned between hexane/aqueous ethanol (12,15), and the soluble components are freed of solvents and determined gravimetrically. For lack of specific nomenclature, the botanochemicals isolated by this technique have been referred to as "whole plant oil," "polyphenol," and "polymeric hydrocarbon." Actually, components from these extracts need to be further characterized. However, petroleum refinery processes may be sufficiently insensitive to allow use of carbon-hydrogen rich compounds represented by a broad spectrum of structures. For example, consider the diverse chemicals ranging from methanol to natural rubber which have been converted to gasoline (16). Thus, chemical species may be important if chemical intermediates are being generated but may be nonconsequential for production of fuels, solvents, carbon black, and other basic chemicals. 

A solution of pyridine-3,4-diamine (2.5 g, 23 mmol) and ethyl acetoacetate (4.55 g, 35 mmol) in toluene (180 mL) was refluxed for 5 h with azeotropic removal of H20. A mixture of I0A and I0B separated as a solid (2.42 g. 60%). Fractional recrystallization from benzene, followed by MeCN and finally EtOH/ cyclohexane gave 2-methyl-3//-pyrido[3.4-A][1,4]diazepin-4(5//)-one (10A) bright-yellow crystals mp 180-182 C. The more soluble component was 2-methyl-1 //-pyrido[3,4-6] 1,4]diazepin-4(5//)-one (10B) pale-yellow crystals mp 168-171 °C (benzene). 

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