Acid fractions

Vinylacetic acid. Place 134 g. (161 ml.) of allyl cyanide (3) and 200 ml. of concentrated hydrochloric acid in a 1-htre round-bottomed flask attached to a reflux condenser. Warm the mixture cautiously with a small flame and shake from time to time. After 7-10 minutes, a vigorous reaction sets in and the mixture refluxes remove the flame and cool the flask, if necessary, in cold water. Ammonium chloride crystallises out. When the reaction subsides, reflux the mixture for 15 minutes. Then add 200 ml. of water, cool and separate the upper layer of acid. Extract the aqueous layer with three 100 ml. portions of ether. Combine the acid and the ether extracts, and remove the ether under atmospheric pressure in a 250 ml. Claisen flask with fractionating side arm (compare Fig. II, 13, 4) continue the heating on a water bath until the temperature of the vapour reaches 70°. Allow the apparatus to cool and distil under diminished pressure (compare Fig. II, 20, 1) , collect the fraction (a) distilling up to 71°/14 mm. and (6) at 72-74°/14 mm. (chiefly at 72 5°/ 14 mm.). A dark residue (about 10 ml.) and some white sohd ( crotonio acid) remains in the flask. Fraction (6) weighs 100 g. and is analytically pure vinylacetic acid. Fraction (a) weighs about 50 g. and separates into two layers remove the water layer, dry with anhydrous sodium sulphate and distil from a 50 ml. Claisen flask with fractionating side arm a further 15 g. of reasonably pure acid, b.p. 69-70°/12 mm., is obtained. 

Ethyl p-phenylethyl ketone. Use 100 g. of pure hydrocinnamic acid and 200 g. (201 -5 ml.) of pure propionic acid. Fractionation of the distillate yields 70 g. of diethyl ketone (b.p. 100-102°), 72 g. of ethyl p-phenyl-ethyl ketone (b.p. 245-249° the pure ketone boils at 248°), and 18 g, of crude di-p-phenylethyl ketone (high b.p. residue). 

Process Sequence. The process sequence consists of recovery of tall oil soap from the pulping blackhquor, acidulation, ie, conversion of the soap into CTO with sulfuric acid, fractional distillation to separate rosin, and fatty acids and purification of the fatty acid fraction. 

Typical composition (in per cent of acid fraction) of the common resin acids in rosins obtained from different sources [22]... 

On oxidation with chromic acid in dilute sulphuric acid, cevine produces an acid fraction, which on heating at 180° gives a good yield of decevinic acid, C14H14O, m.p. 273-8° (dec.), [a] f° 47-6° (pyridine). 

Leonard and Elderfield have also carried out degradation experiments with alstonine and its tetrahydride. On fusion with potassium hydroxide at 300-350° in nitrogen, alstonine furnishes barman (p. 490) and indefinite basic and acidic fractions. Tetrahydroalstonine on like treatment produces barman, worharman, and three unidentified bases, each of which fluoresces blue in alcoholic hydrochloric acid Base A, C4,H4gN2, m.p. 171-5 to 172-5°, forms a picrate, m.p. > 267° is probably a substituted -carboline. Base B, or 18 3, gives apicrate, m.p. 261° (dec.). Base C,... 

As is well-known, nucleic acids consist of a polymeric chain of monotonously reiterating molecules of phosphoric acid and a sugar. In ribonucleic acid, the sugar component is represented by n-ribose, in deoxyribonucleic acid by D-2-deoxyribose. To this chain pyrimidine and purine derivatives are bound at the sugar moieties, these derivatives being conventionally, even if inaccurately, termed as pyrimidine and purine bases. The bases in question are uracil (in ribonucleic acids) or thymine (in deoxyribonucleic acids), cytosine, adenine, guanine, in some cases 5-methylcytosine and 5-hydroxymethylcyto-sine. In addition to these, a number of the so-called odd bases occurring in small amounts in some ribonucleic acid fractions have been isolated. 

Abscisin II is a plant hormone which accelerates (in interaction with other factors) the abscission of young fruit of cotton. It can accelerate leaf senescence and abscission, inhibit flowering, and induce dormancy. It has no activity as an auxin or a gibberellin but counteracts the action of these hormones. Abscisin II was isolated from the acid fraction of an acetone extract by chromatographic procedures guided by an abscission bioassay. Its structure was determined from elemental analysis, mass spectrum, and infrared, ultraviolet, and nuclear magnetic resonance spectra. Comparisons of these with relevant spectra of isophorone and sorbic acid derivatives confirmed that abscisin II is 3-methyl-5-(1-hydroxy-4-oxo-2, 6, 6-trimethyl-2-cyclohexen-l-yl)-c s, trans-2, 4-pen-tadienoic acid. This carbon skeleton is shown to be unique among the known sesquiterpenes. 

In a falling film evaporator (4) a water-paraffin mixture is distilled off and completely pumped back to the reactor. The resulting product is separated into a 60% sulfuric acid fraction and paraffin-containing alkanesulfonic acid (5), which is bleached by hydrogen peroxide (6). In a stirred vessel (7) the alkanesulfonic acid is neutralized by 50% sodium hydroxide solution until the pH is exactly 7. The composition of the neutralized product is also given in Table 2. 

Characterization of Aquatic Humic Acid Fractions by Fluorescence Depolarization Spectroscopy... 

In this chapter, we present the theory and results of measurements on humic acid fractions using fluorescence techniques. The fluorescence techniques are attractive for this application because of the natural fluorescence of humic materials, the hi sensitivity of fluorescence detection, and the ability to directly observe the morphology of the molecule in aqueous solutions without the need for drying or applying harsh chemical conditions. Several interesting types of information are obtained from fluorescence measurements ... 

GOLDBERG AND NEGOMIR Aquatic Humic Acid Fractions... 

This chapter presents new information about the physical properties of humic acid fractions from the Okefenokee Swamp, Georgia. Specialized techniques of fluorescence depolarization spectroscopy and phase-shift fluorometry allow the nondestructive determination of molar volume and shape in aqueous solutions. The techniques also provide sufficient data to make a reliable estimate of the number of different fluorophores in the molecule their respective excitation and emission spectra, and their phase-resolved emission spectra. These measurements are possible even in instances where two fluorophores have nearly identical emission specta. The general theoretical background of each method is presented first, followed by the specific results of our measurements. Parts of the theoretical treatment of depolarization and phase-shift fluorometry given here are more fully expanded upon in (5,9-ll). Recent work and reviews of these techniques are given by Warner and McGown (72). 

On the other hand a shift on the molecular weight distribution to lower values of the acidic fraction it was found. 

Figure 3. Size-exclusion chromatography on Biogel P4 of fraction IPN obtained after anion-exchange chromatography. Fractions (2.5 ml each) were pooled as indicated. — - neutral sugars, — uronic acid. Fractions 1, 2, 3. .. were named later as fractions IPN 1, IPN 2, IPN 3. .. respectively.

L. Zelles, A. Palojarvi, E. Kandeler, M. VonLut/.ow, K. Winter, Q. Y. Bai. Changes in. soil mierobial properties and phospholipid fatty acid fractions after chloroform fumigation. Soil Biol. Biochem. 29 1325 (1997). 

Flgiire 8.11 Solvent fractionation scheae for isolating neutral, base, and acid fractions fron a suple soluble in aethylene chloride. 

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