Isolation by distillation

From nitriles by treatment with anhydrous Stannous chloride dissolved in ether saturated with hydrogen chloride the resulting crystaUine aldimine stannichloride, [(RCH=NHj)2] SnCl, or (RCH=NH,HCl)2SnCl4, is hydrolysed by warm water, and the aldehyde is isolated by distillation with steam or by extraction with a solvent (Stephen reaction), for example, for R = CH3(CH2)4, i.e., n-amyl ... 

By the action of concentrate aqueous ammonia solution upon esters. This process is spoken of as ammonolysls of the ester, by analogy with hydrolysis applied to a similar reaction with water. If the amide is soluble in water, e.g., acetamide, it may be isolated by distillation, for example ... 

The benzyl chloride may also be isolated by distillation under atmospheric pressure. The material boiling between 165° and 185° is collected and redistilled the final product is collected at 178-182° (pure benzyl chloride has b.p. 179°). The resulting benzyl chloride is, however, of lower purity unless an efficient fractionating column is used. 

Oximes, hydrazines and semicarbazones. The hydrolysis products of these compounds, t.e., aldehydes and ketones, may be sensitive to alkali (this is particularly so for aldehydes) it is best, therefore, to conduct the hydrolysis with strong mineral acid. After hydrolysis the aldehyde or ketone may be isolated by distillation with steam, extraction with ether or, if a solid, by filtration, and then identified. The acid solution may be examined for hydroxylamine or hydrazine or semicarbazide substituted hydrazines of the aromatic series are precipitated as oils or solids upon the addition of alkali. 

The methanol carbonylation is performed ia the presence of a basic catalyst such as sodium methoxide and the product isolated by distillation. In one continuous commercial process (6) the methyl formate and dimethylamine react at 350 kPa (3.46 atm) and from 110 to 120°C to effect a conversion of about 90%. The reaction mixture is then fed to a reactor—stripper operating at about 275 kPa (2.7 atm), where the reaction is completed and DMF and methanol are separated from the lighter by-products. The cmde material is then purified ia a separate distillation column operating at atmospheric pressure. 

The mixed monocyclic aromatics are called BTX as an abbreviation for ben2ene, toluene, and xylene (see Btxprocessing). The benzene and toluene are isolated by distillation, and the isomers of the xylene are separated by superfractionation, fractional crystallisation, or adsorption (see Xylenes and ethylbenzene). Bensene is the starting material for styrene (qv), phenol (qv), and a number of fibers and plastics. Toluene (qv) is used to make a number of... 

Herm/es/Djnamit JS obe/Process. On a worldwide basis, the Hercules Inc./Dynamit Nobel AG process is the dorninant technology for the production of dimethyl terephthalate the chemistry was patented in the 1950s (67—69). Modifications in commercial practice have occurred over the years, with several variations being practiced commercially (70—72). The reaction to dimethyl terephthalate involves four steps, which alternate between liquid-phase oxidation and liquid-phase esterification. Two reactors are used. Eirst, -xylene is oxidized with air to -toluic acid in the oxidation reactor, and the contents are then sent to the second reactor for esterification with methanol to methyl -toluate. The toluate is isolated by distillation and returned to the first reactor where it is further oxidized to monomethyl terephthalate, which is then esterified in the second reactor to dimethyl terephthalate. 

Commercially, a small amount of the 4,4 -MDA is isolated by distillation from PMDA. Depending on the process employed, the removal of MDA can be partial (as is done with the isocyanates) or total. Partial removal of MDA gives some processiag latitude but yields of 4,4 -MDA are reduced. Distillation residues from PMDA manufacture that contain less than 1% MDA pose a disposal problem. Processes for the regeneration of MDA by heating these residues ia the presence of aniline and an acid catalyst have been patented (33—35). Waste disposal of PMDA is expensive and reclamation processes could become commercially viable. The versatility of the isocyanate process, however, can be used to avoid the formation of low MDA content distillation residues. 

The sesquiterpenes found in essential oils have low volatilities compared with monoterpenes and so are isolated mainly by steam distillation or extraction, but some are also isolated by distillation or crystallization. Most of the sesquiterpene alcohols are heavy viscous Hquids and many crystallize when they are of high enough purity. Sesquiterpene alcohols are important in perfume bases for their odor value and their fixative properties as well. They are valuable as carriers of woody, balsamic, or heavy oriental perfume notes. 

Trichloroacetone [921-03-9] (13a) is prepared by chlorination of acetone. The reaction is nonselective and the required compound is isolated by distillation. The selectivity has been improved by catalyzing the reaction with iodine (31). 

The reaction was carried out on a 1-20 iiiniol scale 1n dlchlorotnethane. Yields after isolation by distillation or thin layer chromatography. (I) Me3SiCH2CH=CH2. (11) Me3SiCH2CH=C(0113)2. 

Pure l-(N-pyrrolidino)-l-cyclododecene, bp 144 C (1.5 inn), may be isolated by distillation through a Vlgreux column. 

Excess lithium is destroyed by the c irc/w/addition of 1-2 ml of ethanol, and hydrolysis of the reaction mixture is then effected by the addition of a mixture of ice (50 g) and water (100 ml). The solution is then acidified to pH 2 by the addition of 5 A hydrochloric acid, followed by rapid stirring for 1 or 2 minutes to hydrolize the HMPT. The aqueous solution is extracted with ether, the ether solution is dried with magnesium sulfate, then filtered, and the ether is evaporated. The product is isolated by distillation of the residue. 

Preparation of 1,3-Diphenyl-2,2-Dimethylpropanone-1 Sodamide was prepared from 12.5 grams of sodium added in small portions to 600 cc of liquid ammonia with 1 gram of hydrous ferric chloride as catalyst. The ammonia was replaced by 200 cc of dry toluene and without delay a solution of 74 grams of isobutyrophenone and 76.5 grams of benzyl bromide in 200 cc of benzene was slowly added with stirring. The reaction mixture was heated on a boiling water bath for 48 hours. Water was then added, the organic layer separated and the product isolated by distillation. The 1,3-diphenyl-2,2-dimethylpropanone-1 boiled from 142°-143°C at a pressure of 3 mm, t ° 1.5652. 

The authors describe a stabilizing effect of the ionic liquid on the palladium catalyst. In almost all reactions no precipitation of elemental palladium was observed, even at complete conversion of the aromatic halide. The reaction products were isolated by distillation from the nonvolatile ionic liquid. 

Ethyl Y-phenylbutyrate is prepared in 85-88 per cent yields by refluxing for three hours a mixture of 50 g. of 7-phenylbutyric acid (Org. Syn. 15, 64), 150 cc. of alcohol dried over lime, and 5 g. of concentrated sulfuric acid. The ester is isolated by distilling 100 cc. of the alcohol under reduced pressure from a steam bath, diluting with 200 cc. of water, separating, and extracting the aqueous layer twice with 50-cc. portions of ether. The combined ester and ether layers are dried with sodium sulfate, the ether removed, and the residue distilled under diminished pressure the portion boiling at 144-147° at 19 mm. is collected. 

Equimolar amounts of TDSC1 and TfOH were heated at 60 °C for 5 h. The product was isolated by distillation, b.p. 40-42 °C/0.15 mmHg. 

Continuous recovery requires AA crystals having an average diameter of ca. 40-50 nm.5 Such crystals are obtained by continuously introducing die hot hydrolysate containing 10-20% AA into an agitated crystallization vessel while maintaining an average temperature of 20-30°C. The slurry obtained from the crystallization vessel is filtered to collect die AA crystals, and the filtrate which contains the HMDA acid salt is continuously neutralized with calcium hydroxide. The calcium salt formed is removed by filtration, and the HMDA in the filtrate is isolated by distillation. 

The oligomerization leads to a mixture of a-olefins. In the first step the a-olefins are isolated by distillation. These a-olefins are of a suitable side chain for use in the manufacture of surfactants (starting material for alcohols and deriva-... 

The first bis(T7 -2,3,5-tricarbahexaboranyl)nickel sandwich is generated by the reaction of Ni(C2H4)3 and the 2,3-dihydro-1,3-diborole Et2C2B2Mc2CH2. Besides [(MeB)Et2C2B2Mc2CH]Ni (12%) the tricarbahexaboranyKallyDnickel complex [(MeB)Et2C2B2Me2CH]Ni(MeCHCHCHEt) can be isolated by distillation. 

Triflic acid (0.032 g) is added through a septum to a stirred mixture of 2,5-hex-andione 1487 (1.95 g, 0.017 mol) and HMDS 2 (7.4 mb, 0.035 mol) whereupon an exothermic reaction results and hexamethyldisiloxane 7 is removed by distillation through a short-path distillation head. When the reaction subsides (15 min) 81% pure 2,5-dimethylpyrrole 1494, b.p. 165 °C, is isolated by distillation [41]. 

The well documented synthetic method for 37 is chlorination of cyclopropyl-methylketone followed by base treatment [29]. However, this method did not provide a suitable impurity profile. The most convenient and suitable method we found was the one-step synthesis from 5-chloro-l-pentyne (49) by addition of 2equiv of base, as shown in Scheme 1.18 [21, 30]. Two major impurities, starting material 49 and reduced pentyne, had to be controlled below 0.2% each in the final bulk of 37, to ensure the final purity of Efavirenz . Acetylene 37 was isolated by distillation after standard work-up procedure. 

The oxidant appears safe when prepared and used in dichloromethane solution, but attempted isolation by distillation led to a violent explosion. 

During work-up of the products of ozonolysis of R- and S-citronellic acids, a substantial quantity of the highly explosive trimeric acetone peroxide (3,3,6,6,9,9-hexamethyl-l,2,4,5,7,8-hexoxonane) was unwittingly isolated by distillation at 105-135°C to give the solid m.p. 95°C. The peroxide appears to have been produced by ozonolysis of the isopropylidene group in citronellic acid, and presumably the same could occur when any isopropylidene group is ozonised. Appropriate care is advised. 

A small amount (50-100 g.) of a higher boiling material remains in the flask. This is mainly diphenyl sulfone, which may be isolated by distillation under reduced pressure (b.p. 2250/1 o 111m.) and recrystallization from methyl alcohol. It forms colorless crystals which melt at 128°. 

At the end of the war, he returned to Munich as Associate Professor and Director of the Laboratory of Organic Chemistry. The Department was then under Richard Willstatter s direction, and Meyer occupied the same position as the one held for many years by Willstatter under Baeyer s leadership. He resumed his investigation on keto-enol tautomerism, and, in collaboration with H. Hopff, isolated by distillation the pure enol form of ethyl acetoacetate. Other work from the same period included an examination of the action of nitric acid on phenol and phenol ether (with W. Reppe and W. E. Elbers), and a study of narcosis (with H. G. Billroth)— an extension of his father s work. 

Deuteration studies with acetic acid-d4 (99.5% atom D) as the carboxylic acid building block, ruthenium(IV) oxide plus methyl iodide-d3 as catalyst couple and 1/1 (C0/H2) syngas, were less definitive (see Table III). Typical samples of propionic and butyric acid products, isolated by distillation in vacuo and glc trapping, and analyzed by NMR, indicated considerable scrambling had occurred within the time frame of the acid homologation reaction. 

The direct high yield synthesis of oxaspiropentanes from almost any type of aldehyde or ketone represents a particularly useful transformation because of the high reactivity of such compounds. This approach proves to be exceptionally simple. The DMSO reaction mixture can be directly extracted with pentane or hexane, the hydrocarbon solvent removed and the product isolated by distillation or crystallization. Since diphenyl sulfide is the only by-product extracted with the oxaspiropentane, the mixture can normally be used for most further synthetic transformations. Table 2 summarizes some of the oxaspiropentanes prepared by this method. 

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