Cyclohexane-ethyl acetate

The most commonly used catalysts are palladized charcoal or calcium carbonate and platinum oxide. For better isotopic purity, the use of platinum oxide may be preferred for certain olefins since the substrate undergoes fewer side reactions while being chemisorbed on the platinum surface as compared to palladium.Suitable solvents are cyclohexane, ethyl acetate, tetrahydrofuran, dioxane or acetic acid-OD with platinum oxide. 

To a stirred solution of 1 g (3.48 mmol) of (3R,4R)-4-acetoxy-3-[(R)-l-(( Tt-butyldimethylsilyloxy)ethyl]-2-azetidinone in 20 mL of CH2C12 are added 1.46 g (5.17 mmol) of tetrakis(2-propeny])tin and 49.5 mg (0.348 mmol) of BF3 0(C2H5)2 under a nitrogen atmosphere. After stirring for 15 h at 20 °C, CH2C12 is added and the mixture is washed three times with water and then dried over MgS04. The solvent is removed in vacuo and the residue is purified by flash chromatography (cyclohexane/ethyl acetate 2 1) yield 800 mg (85%) nip 70-77 °C. 

Cyclohexane - Ethyl acetate 50 + 50 Diethyl ether - Dimethyl formamide 99 + 01... 

GPC eluting mixture cyclohexane-ethyl acetate (1 1, v/v) if necessary, redistilled as an azeotropic mixture... 

Applications Open-column chromatography was used for polymer/additive analysis mainly in the 1950-1970 period (cf. Vimalasiri et al. [160]). Examples are the application of CC to styrene-butadiene copoly-mer/(additives, low-MW compounds) [530] and rubbers accelerators, antioxidants) [531]. Column chromatography of nine plasticisers in PVC with various elution solvents has been reported [44], as well as the separation of CHCI3 solvent extracts of PE/(BHT, Santonox R) on an alumina column [532]. Similarly, Santonox R and Ionol CP were easily separated using benzene and Topanol CA and dilaurylthiodipropionate using cyclohexane ethyl acetate (9 1 v/v) [533]. CC on neutral alumina has been used for the separation of antioxidants, accelerators and plasticisers in rubber extracts [534]. Column chromatography of polymer additives has been reviewed [160,375,376]. 

Composition of mobile phases 1 = toluene-ethyl acetate-(98-100%) formic acid (36 12 5. v/v) 2 = cyclohexane-ethyl acetate-(98-100%) formic acid 3 = toluene-ethyl acetate-glacial acetic acid (36 12 5, v/v) 4 = cyclohexane-ethyl acetate-glacial acetic acid (31 14 5, v/v) 5 = n-hexane-ethyl acetate-(98-100%) formic acid (31 14 5, v/v) 6 = toluene-acetone-(98-100%) formic acid (38 10 5, v/v) 7 = n-hexane-ethyl acetate-glacial acetic acid (31 14 5,v/v) 8 = petroleum ether(40-70°C)-ethyl acetate-(98-100%) formic acid (30 15 5, v/v) 9 = carbon tetrachlo-ride-acetone-(98-100%) formic acid (35 10 5, v/v) 10 n-hexane-ethyl acetate-glacial acetic acid (30 20 1.5. v/v) 11 = chloroform-methanol-(98-100%) formic acid (44.1 3 2.35, v/v). Reprinted with permission from I. Jasprica et al. [141]. 

Tamura. K., Morishita, N., and Yamada, T. Ternary and quaternary liquid-liquid equilibria for the water + cyclohexane + ethyl acetate and water + cyclohexane + ethyl acetate + acetic acid systems at the temperature 298.15 K. 7 Chem. Eng. Data, 45(4) 555-558, 2000. 

A solution of 20 mmol of a .s-3-(2-alkyl-l-oxoalkyl)-l, 5-dimethyl-4-phenyl-2-imidazolidinone 5 in 40 mL of dry THF is slowly added at 0 3C to a stirred suspension of lithium aluminum hydride in 30 mL of THF under argon. The mixture is stirred for 1 h, then the reaction is quenched by the cautious addition of methanol, followed by 2M aq hydrochloric acid. Extraction with ethyl acetate is followed by concentration under vacuum and flash chromatography (cyclohexane/ethyl acetate). For specific examples, see Table 12. 

TLC analysis on silica gel 60F-254 plates eluting with (1 1) cyclohexane-ethyl acetate showed the clean formation of ester 3 with Rf = 0.74 (visualized with 0.3% ninhydrin in (97 3) butanol-acetic acid) at the expense of starting material with Rf = 0.4. The sample of the oxazolidine ester was neutralized with a little triethylamine prior to TLC analysis. 

Enantiomeric purity was determined to be 96-98% by 1H NMR analysis of the Mosher esters4 of the alcohols 4 and ent-4 obtained by reduction of the aldehydes 5 and ent-5. To an ice-cold solution of aldehyde 5 (0.10 g, 0.44 mmol) in 5 mL of methanol was added solid sodium borohydride (33 mg, 0.88 mmol). After the mixture was stirred for 30 min at this temperature, the TLC in (7 3) cyclohexane-ethyl acetate showed the clean formation of the alcohol 4. The mixture was treated with 0.05 mL of acetone and concentrated to dryness under reduced pressure. The residue was partitioned between water (10 mL) and ethyl acetate (10 mL) and the phases were separated. The aqueous phase was extracted with three 10-mL portions of ethyl acetate. The combined organic phases were dried with anhydrous sodium sulfate and concentrated under reduced pressure. The residue was purified by flash... 

TLC analysis on Silica Gel 60F-254 plates eluting with cyclohexane-ethyl acetate (7 3) showed the clean formation of product with Rf = 0.69, at the expense of the starting material with Rt = 0.3. If a small amount of starting material was still present at this time, more tert-butyldimethylsilyl trifluoromethanesulfonate (0.22 mL, 0.95 mmol) and 0.2 mL of triethylamine were added and the reaction mixture was stirred for a further 30 min, at which time the TLC analysis generally showed the reaction to be complete. 

TLC analysis on Silica Gel 60F-254 plates eluting with cyclohexane-ethyl acetate (9 1) showed the formation of product with Rt = 0, at the expense of the starting material. 

A mixture of a- or P-73 [Eq. (14)] (1.00 g, 1.5 mmol), activated 4-A powdered molecular sieves (0.6 g), trimethylsilyl azide (300 p,L, 2.2 mmol), and dry CH2C12 (6 mL) was stirred at room temperature for 10 min, and then trimethylsilyl triilate (136 pl>, 0.75 mmol) was added. The mixture was stirred at room temperature for 20 min, then neutralized with Et3N, diluted with CH2C12, filtered through Celite, and concentrated. The residue was eluted from a column of silica gel with 6 1 cyclohexane-ethyl acetate to give 75 (0.86 g, 88%) as a syrup [a]D +33.7° (c 0.7, CHC13). 

To a vigorously stirred mixture of silver nitrate (367 mg, 2.16 mmol), NaOH (173 mg, 4.32 mmol), and water (10 mL) was added a solution of the crude aldehyde (0.47 g) in freshly distilled THF (20 mL). Stirring was continued for 36 h at room temperature, then acetic acid was added up to pH 5, and the mixture was filtered through Celite. The solution was concentrated and the residue was dissolved in 1 1 MeOH-EtjO (20 mL), treated with an etheral solution of diazomethane at 0°C for 20 min, then concentrated. Flash chromatography (5 2 cyclohexane-ethyl acetate) of the residue afforded 77 (0.36 g, 54% from 75) as a syrup [a]D +34.9° (c 1.6, CHC13). 

Into a solution of residue 59 (101 mg, 0.1 mmol) in 20 mL of dry toluene, kept at 60°C, was syringed, during 18 h and under argon, a freshly prepared solution of samarium diiodide in benzene-HMPA (9 1, v/v 6.3 mL, 0.51 mmol) which has been diluted with 3.8 mL of dry benzene. The solvents were distilled off under reduced pressure, and the residue was taken up in 10 mL of diethyl ether. The ether solution was washed with 10% aqueous solution of sodium bisulfite, then water, dried (MgS04), and concentrated. The crude product was dissolved in 1.5 mL of tetrahydrofuran and treated during 30 min at room temperature with 1.5 mL of a 40% aqueous solution of HF. The solution was neutralized with solid sodium carbonate, and concentrated. Flash chromatography on silica gel (cyclohexane-ethyl acetate, 3 1 to 1 2) afforded the product 80 (40.6 mg, 50%), a single isomer, as an amorphous solid. It was characterized by its diacetate [a]D +36° (c 4.0, CHClj). 

To a solution of LDA (40mmol) in THF (200ml) cooled at -45°C, methyl dithioacetate (3.92 ml, 40 mmol) was added dropwise. The yellow colour rapidly disappeared. The mixture was stirred for 5 min. 2-Cyclohexenone (3.92 ml, 40 mmol) was then added dropwise. A yellow colour appeared. The resulting mixture was stirred for 15 min. An aqueous solution of ammonium chloride was added and the mixture partitioned between ether and brine. The organic layer was washed with brine, dried with magnesium sulfate and concentrated. Methyl (cyclohexanone-3-yl)dithioacetate (3) (6.75 g, 33.4 mmol, 83%) was isolated by flash chromatography on silica gel using cyclohexane/ethyl acetate (9 1) as the eluent. 

Olive oil, fat extracts of chicken and fish, lettuce GPC, online 3-mm-ID X 25-cm PSS SDV, 5 /xm Cyclohexane-ethyl acetate (1 1)... 

The product formed was extracted with CH2C12 (4x30 mL) and filtered on Celite. After evaporation of solvent, the product was purified by preparative thin layer chromatography (cyclohexane-ethyl acetate, 9 1) on silica and crystallized. 

Solvent systems A, chloroform-benzene-ethanol (18 2 1) B, chloroform-dioxane (47 3) C, cyclohexane-ethyl acetate (3 1). ... 

The contents of the test-tube are mixed and warmed at 55 °C for 1-5 h. The mixture is cooled and an aliquot portion is spotted on to a TLC plate for separation. Two-dimensional chromatography is carried out on silica gel layers with cyclohexane-ethyl acetate (1 1) and light petroleum-chloroform-diethyl ether-acetic acid (33 33 33 1). Chromatography on polyamide layers is accomplished with heptane-ethyl acetate-butanol (8 1 1). The Rp values of six NBD-amines in these systems [99] are given in Table 4.15. Amounts of less than 15 ng of NBD-amine per spot can be detected. HPLC of some NBD-amines has been carried out using Zipax coated with 0.5% 0,/3 -oxydipropionitrile and 1% tetra-hydrofuran in hexane as the mobile phase (see Section 4.2.4.2.2). 

Solvents 1 = cyclohexane-ethyl acetate (1 1) 2 light petroleum-chloroform-diethyl ether-acetic acid (33 33 33 1) and 3 - heptane-ethyl acetate-butanol (8 1 1). 

Method. The derivatives are formed by shaking the sample (dissolved in acetone) for 1 h at 45 °C with a 3-5 molar excess of recrystallized DNS-C1. The reaction is buffered at pH 10.8.0.25 ml of 1N sodium hydroxide is then added in order to hydrolyze the unchanged DNS-C1. The derivatives are extracted with 3 ml of ethyl acetate after addition of 1 ml of a saturated aqueous solution of sodium chloride to the reaction mixture. The organic phase is used for TLC on activated layers of silica gel G. The cannabinoids yield mono-DNS derivatives with the exception of cannabidiol which forms a bis-DNS derivative. The following solvent systems are satisfactory for separation of cannabinoids on silica gel A, benzene-acetone (9 1) B, cyclohexane-ethyl acetate (5 1) C, cyclohexane-acetone-diethylamine (20 4 1) and D, cyclohexane-acetone-triethylamine (20 4 1). The R f values of nine cannabinoids in the above solvent systems are given in Table 4.25. 

R)-( + )-Pulegone 2 (2.0 g, 13.14 mmol) and ort/zo-phenylenediamine 1 (1.42 g, 13.14 mmol) were dissolved in 30 ml of dry toluene (Scheme A.31). Subsequently, the mixture was refluxed, the solvent evaporated and the residue subjected to column chromatography over silica gel (cyclohexane-ethyl acetate 7 3), producing 2.16 g (68%) of compound 3. Melting point 105°C. 

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