Non-volatile Carboxylic Acids Research Articles

Organics in soda-anthraquinone black liquors from hot-water-extracted non-wood feedstocks

ABSTRACT The chemical compositions of black liquors (BLs) obtained from the soda-anthraquinone (AQ) pulping of untreated and hot-water-extracted non-wood feedstocks (okra stalk, miscanthus stalk, and wheat straw) were determined. These under-utilized renewable and widely available feedstocks could provide a cheaper source for producing fiber and precursors for manufacturing green chemicals. These BLs were mainly characterized in terms of carbohydrate-derived volatile carboxylic acids (acetic and formic acids) and non-volatile carboxylic acids (hydroxy acids) as well as lignin. Additionally, in each case, the average molar mass and molar mass distribution of the dissolved lignin were measured. Results indicated typical effects of hot-water extraction; for example, in the case of hot-water-extracted feedstocks, compared to untreated feedstocks, more aliphatic carboxylic acids were formed, whereas in both cases the removal of lignin was similar. The maximum total amounts of aliphatic carboxylic acids were in the following order: okra/150 °C/P200 (39 g L−1) > miscanthus/150 °C/P200 (31 g L−1) > wheat/150 °C/P200 (15 g L−1). On the other hand, the total dissolved lignin was in the following order: wheat/150 °C/P200 (45 g L−1) > miscanthus/150 °C/P200 (35 g L−1) ≈ okra/140 °C/P50 (35 g L−1). The hot-water extraction also affected weight average molar mass (w) values of the dissolved lignin in BLs. When the pre-treatment conditions became harsher, the w values increased; the lowest value detected was 4160 g mol−1 for lignin in the okra BL from the untreated feedstock, and the highest value, 8730 g mol−1, was obtained for lignin in the wheat BL from pre-treated feedstock (150 °C/P200). All the data obtained are of importance when planning the overall strategy for recovering the non-wood-derived aliphatic carboxylic acids and lignin formed in this kind of integrated biorefinery approach.

Peptide conjugates of benzene and toluene metabolites in English ryegrass

Biotransformation of [1-6-14C]benzene and [1-14C]toluene in English ryegrass (Lolium perenne L.) seedlings was investigated. Vapors of these compounds were absorbed by the leaves of this plant. Benzene and toluene were oxidized, forming phenol and benzoic acid, respectively. A portion of phenol and benzoic acid was bound by low-molecular-weight peptides forming conjugates. A qualitative amino acid composition of the peptides involved in the conjugation was determined. After removing plants from the atmosphere containing [1-6-14C]benzene and [1-14C]toluene, the radioactivity of the conjugates gradually decreased. This process was accompanied by the evolution of 14CO2, indicating the breakdown of these conjugates. Radioactive compounds thus formed were oxidized, yielding carbon dioxide. A portion of phenol and benzoic acid, along with peptide conjugation, was subjected to further oxidative transformations up to disruption of the aromatic ring. By this pathway, nonvolatile carboxylic acids, such as muconic, fumaric, succinic, malic, malonic, glycolic, and glyoxylic, were formed. Using electron microscopy, a damaging effect of benzene on the cell ultrastructure of English ryegrass leaves was shown, and this toxic effect depended on the benzene concentration.

Thermoplastic starch modification during melt processing: Hydrolysis catalyzed by carboxylic acids

The melt processing of glycerol-plasticized starch in the presence of non-volatile carboxylic acids resulted in a progressive loss of its molar mass, because the residual moisture in the mixture induced an acid-catalyzed hydrolysis of the ether linkages in its polysaccharide chains. The study of this reaction provided a useful means of adjusting its course and thus of preparing starch materials with controlled properties.

Interpretation of electrospray and atmospheric pressure chemical ionization mass spectra of 10-formyl-7,8-dihydrofolic acid and 5-formyl-5,6,7,8-tetrahydropteroic acid.

Interpretation of positive- and negative-ion electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) mass spectra of 10-formyl-7,8-dihydrofolic acid (10-FDHFA) and 5-formyl-5, 6,7,8-tetrahydropteroic acid (5-FTHPA) is discussed. ESI mass spectra enable unambiguous molecular weight (MW) determination. In addition to the determination of MW, APCI mass spectra also make possible structure elucidation of 10-FDHFA and 5-FTHPA. ESI and APCI are complementary ionization techniques and appear to be useful alternatives to conventional electron ionization (EI) for the structure elucidation of non-volatile carboxylic acids. Prior to mass spectral analysis, the acids investigated were separated by reverse-phase high-performance liquid chromatography (HPLC).

Conversion of xylan, starch, and chitin into carboxylic acids by treatment with alkali

Treatment of xylan, starch, and chitin with m and 3 m sodium hydroxide at 175° and 190° gave mixtures of non-volatile carboxylic acids in yields of 50–70%, 40–60%, and 5–13%, respectively, in which >60 hydroxy monocarboxylic acids and dicarboxylic acids were identified. The main compounds were glycolic, lactic, 2-hydroxybutanoic, 3-deoxypentonic, xyloisosaccharinic, and 3,4,5-trideoxyheptaric acids from xylan; glycolic, lactic, 3,4-dideoxypentonic, glucoisosaccharinic, and 3,4-dideoxyhexaric acids from starch; and glycolic, lactic, 2-hydroxybutanoic, and 3,4-dideoxyhexaric acids from chitin.

Simultaneous gas chromatography of volatile and non-volatile carboxylic acids as tert.-Butyldimethylsilyl derivatives

Solid phase extraction with subsequent ion pair formation and silylation was investigated for the simultaneous trace enrichment of volatile and non-volatile carboxylic acids from complex aqueous samples. The solid phase extraction of acids was performed using Chromosorb P as the solid sorbent. The ether eluate was treated with triethylamine. The resulting triethylammonium salts of the acids were converted to stable tert.-butyldimethylsilyl (TBDMS) derivatives, which were analyzed by gas chromatography (GC) and GC-mass spectrometry. The characteristic M - 57 ions in the mass spectra of TBDMS derivatives enabled rapid identification of acids. The application of the method to the organic acid profiling of urine and saliva samples is demonstrated.

Determination of non-volatile carboxylic acids

カルボン酸とアミンとによる塩生成反応を利用した反応ガスクロマトグラフィーにより,難揮発性カルボン酸を定量した.試料カルボン酸をアルコールまたはクロロホルム溶液として,あらかじめ担体を充てんした反応カラム中に注入後,溶媒を留去し,これを試料気化室と分離カラムとの間に接続した.次に試料気化室より一定量のn-ヘキシルアミンをくりかえし注入し,反応カラム中のカルボン酸と塩生成反応を起こさせた。反応により生成した塩は反応カラム中に滞留し,過剰のアミンは分離カラムへ送られクロマトグラム上にピークを与えた.試料気化室から注入されたアミンの総量と,クロマトグラム上の過剰アミンの定量値との差から,対応する試料カルボン酸量を定量した.キャリヤーガス流量,試料カルボン酸の量および濃度,1回に注入するアミン量などの条件の変化による定量結果への影響を調べた.その結果,最適条件下では5種類の難揮発性の一塩基性カルボン酸について,回収率はほぼ100%,標準偏差は 2.2～2.8% であった.

Application of paper chromatography to the separation of nonvolatile carboxylic acids.

THE separation of several non-volatile carboxylic acids by paper chromatography has been described by Lugg and Overell1,2. These workers found that it was impossible to carry out the separation with neutral solvents because the ionization of the acids caused the spots to ‘tail’. They overcame the difficulty by swamping both the stationary and mobile phases with formic or acetic acid. Removal of the swamping acid was then a necessary and sometimes tedious operation before the non-volatile acids could be revealed by spraying with an acid-base indicator.