Peroxide-Ammonia Delignification of Pine Wood

Oxidative delignification of pine wood by hydrogen peroxide in aqueous ammonia was studied. A new method for producing cellulose and N-containing organic fertilizers was developed. It was demonstrated that a solution of hydrogen peroxide (3-9%) in aqueous ammonia delignified extensively wood to produce cellulose in yields up to 54.6% with a residual lignin content up to 1.1%. The process of pine-wood delignification by hydrogen peroxide in aqueous ammonia was described satisfactorily by a first-order kinetic equation.     

Catalytic synthesis of nitriles

Summary An effective catalyst for the conversion of isoalkanols into nitriles under the action of ammonia is pure zinc oxide at 390°. In presence of zinc oxide at this temperature, isobutyl alcohol reacts with ammonia with formation of isobutyronitrile in yields of up to 76.6% and isopentyl alcohol gives isovaleronitrile under the same conditions in yields of up to 71.4%.     

Direct conversion of aldehydes to amides,tetrazoles, and triazines in aqueous media by one-pot tandem reactions

A variety of aldehydes reacted with iodine in ammonia water at room temperature to give the nitrile intermediates, which were trapped by addition of hydrogen peroxide, sodium azide, or dicyandiamide to produce their corresponding amides, tetrazoles, and 1,3,5-triazines in modest to high yields. The one-pot tandem reactions were conducted in water media, and the products were obtained simply by extraction or filtration.     

Ammonia fiber expansion pretreatment and enzymatic hydrolysis on two different growth stages of reed canarygrass

Plant materials from the vegetative growth stage of reed canarygrass and the seed stage of reed canarygrass are pretreated by ammonia fiber expansion (AFEX) and enzymatically hydrolyzed using 15 filter paper units (FPU) cellulase/g glucan to evaluate glucose and xylose yields. Percent conversions of glucose and xylose, effects of temperature and ammonia loading, and hydrolysis profiles are analyzed to determine the most effective AFEX treatment condition for each of the selected materials. The controls used in this study were untreated samples of each biomass material. All pretreatment conditions tested enhanced enzyme digestibility and improved sugar conversions for reed canarygrass compared with their untreated counterparts. Based on 168 h hydrolysis results using 15 FPU Spezyme CP cellulase/g glucan the most effective AFEX treatment conditions were determined as: vegetative growth stage of reed canarygrass--100 degrees C, 60% moisture content, 1.2:1 kg ammonia/kg of dry matter (86% glucose and 78% xylose) and seed stage of reed canarygrass--100 degrees C, 60% moisture content, 0.8:1 kg ammonia/kg of dry matter (89% glucose and 81% xylose). Supplementation by commercial Multifect 720 xylanase along with cellulase further increased both glucose and xylose yields by 10-12% at the most effective AFEX conditions.     

由2-烷基蒽醌一步法制备2-烷基蒽

本文报道了以2-烷基蒽醌为原料,结晶硫酸铜为催化剂,锌粉为还原剂于浓氨水(25%～28%)中一步法制备2-烷基蒽.产物通过硅胶柱层析,收率范围:55%～90%.文中从取代基的电子效应和空间位阻角度分析了产率的变化规律.同时考察了其它几种无机盐用作催化剂的催化作用.     

Pretreatment with ammonia water for enzymatic hydrolysis of corn husk, bagasse, and switchgrass

Bagasse, corn husk, and switchgrass were pretreated with ammonia water to enhance enzymatic hydrolysis. The sample (2 g) was mixed with 1–6 mL ammonia water (25–28% ammonia) and autoclaved at 120°C for 20 min. After treatment, the product was vacuum-dried to remove ammonia gas. The dried solid could be used immediately in the enzymatic hydrolysis without washing. The enzymatic hydrolysis was effectively improved with more than 0.5 and 1 mL ammonia water/g for corn husk and bagasse, respectively. In bagasse, glucose, xylose, and xylobiose were the main products. The adsorption of CMCase and xylanase was related to the initial rate of enzymatic hydrolysis. In corn husks, arabinoxylan extracted by pretreatment was substantially unhydrolyzed because of the high ratio of arabinose to xylose (0.6). The carbohydrate yields from cellulose and hemicellulose were 72.9% and 82.4% in bagasse, and 86.2% and 91.9% in corn husk, respectively. The ammonia/water pretreatment also benefited from switchgrass (Miscanthus sinensis and Solidago altissima L.) hydrolysis.     

Deficiency of Cellulase Activity Measurements for Enzyme Evaluation

Switchgrass was used as a model feedstock to determine the influence of pretreatment conditions and biomass quality on enzymatic hydrolysis using different enzyme products. Dilute sulfuric acid and soaking in aqueous ammonia pretreatments were used to produce biomass with varied levels of hemicellulose and lignin sheathing. Pretreated switchgrass solids were tested with simple enzymatic hydrolysis and simultaneous saccharification and fermentation (SSF) with three commercial enzyme products: Accellerase 1000 (Genencor), Spezyme CP (Genencor)/Novozyme 188 (Novozymes), and Celluclast/Novozyme 188 (Novozymes). Enzymes were loaded on a common activity basis (FPU/g cellulose and CBU/g cellulose). Despite identical enzyme loadings, glucose yields were significantly different for both acid and alkaline pretreatments but differences diminished as hydrolysis progressed for acid-pretreated biomass. Cellobiose concentrations in Accellerase treatments indicated an initial β-glucosidase limitation that became less significant over time. SSF experiments showed that differences in glucose and ethanol yields could not be attributed to enzyme product inhibition. Yield discrepancies of glucose or ethanol in acid pretreatment, alkaline pretreatment, and acid pretreatment/SSF were as much as 15%, 19%, and 5%. These results indicate that standardized protocols for measuring enzyme activity may not be adequate for assessing activity using pretreated biomass substrates.     

Synthesis and reactions of benzo[b]thieno[2,3-c]pyrylium pairs

Benzo[b]thieno[2,3-c]pyrylium perchlorates were obtained in high yields in the acylation of benzo[b]thien-3-ylacetone with aliphatic acid anhydrides in the presence of 70% perchloric acid. Treatment of the products with ammonia converts them to benzo[b]thieno[2,3-c]pyridines (in yields higher than 90%), whereas hydroxy and dialkylamino derivatives of dibenzothiophene were obtained in up to 50% yields by treatment of the products with alkalis or secondary amines, respectively.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1351–1354, October, 1981.     

Stereoselective synthesis of new monoterpene β-amino alcohols

The regio- and stereoselective osmium-catalysed aminohydroxylation of (+)-2-carene (99% ee), and (+)-3-carene (99% ee), (?)-β-pinene (99% ee) and (?)-camphene (75% ee) with chloramine-T is described. The products β-hydroxy-p-toluenesulfonamides were reduced with sodium in liquid ammonia to give the corresponding β-amino alcohols with 48–83% yields. The methylation-reduction of β-hydroxy-p-toluenesulfonamides gave β-methylamino alcohols with 33–55% yields.     

Acid-catalyzed cyclization of alkoxyacryloylureas to 2,4(1H,3H)pyrimidinediones

1-Phenylthymine and the carbocyclic analog of thymidine were obtained in yields of 84-87% by cyclizing the appropriate 3-methoxy-2-methylacryloylureas in dilute sulfuric acid. High yields of 1-phenylthymine also resulted when the cyclization was carried out in trifluoroacetic acid, in acetic acid containing toluenesulfonic acid (TSA), or by fusion of the urea with a catalytic amount of TSA. In comparison, the typical aqueous-alkali catalyzed cyclizations gave lower yields of the two thymines, and cleavage of the acryloylureas was shown to occur. However, cyclization in concentrated aqueous ammonia produced high yields of both thymine derivatives.     

Convenient synthesis of 4-trifluoromethyl-substituted imidazole derivatives

Mesoionic 4-trifluoroacetyl-1,3-oxazolium-5-olates (1), obtained from the reaction of N-acyl-N-alkylglycines (2) with trifluoroacetic anhydride, react with ammonia to give 4-trifluoromethyl-3,4-dihydroimidazoles (3) in high yields. Dehydration of 3 gives 4-trifluoromethylimidazoles (4) in high yields. The novel ring transformation of 1 into 3 occurs via a regioselective attack of ammonia on the C-2 position of the ring.     

A Continuously Regenerable Chiral Ammonia Borane for Asymmetric Transfer Hydrogenations

A novel chiral ammonia borane was designed and developed through the dehydrogenation of ammonia borane with a chiral phosphoric acid, which was highly effective for the asymmetric transfer hydrogenation of imines and β‐enamino esters to afford high levels of reactivities and enantioselectivities. Significantly, this chiral ammonia borane can be continuously regenerated during the transfer hydrogenation with the assistance of water and ammonia borane, which made it possible to obtain satisfactory results using only 0.1 mol % of the chiral phosphoric acid. Notably, the role of chiral phosphoric acid is to produce the chiral ammonia borane.     

Amination of 4-nitropyridazine 1-oxides by liquid ammonia/potassium permanganate

Treatment of 4-nitropyridazine 1-oxide ( 1a ) 3-methoxy-6-chloro-4-nitropyridazine 1-oxide ( 1b ) or 3,6-dimethoxy-4-nitropyridazine 1-oxide ( 1c ) with a solution of potassium permanganate in liquid ammonia gives in reasonable-to-good yields the corresponding 5-amino-4-nitropyridazine 1-oxides (75%, 54% and 62%, respectively). 3,6-Dimethoxypyridazine ( 4a ) and 3-methoxypyridazine ( 4b ) are converted into the corresponding 4-aminopyridazines 6a,6b on treatment with potassium amide/liquid ammonia/potassium permanganate (yield 50 and 22% respectively). In the last-mentioned reaction besides 6b 3,3′-dimethoxy 4,4′-bipyridazine (7, 23%) was obtained. It is suggested that the neutral 1:1 σ-adducts formed between ( 1a–1c ) and liquid ammonia and the anionic σ-adducts, formed between ( 5a–5b ) and potassium amide are intermediates in this amino-oxidation reaction.     

Optimizing ammonia processing conditions to enhance susceptibility of legumes to fiber hydrolysis

A warm-season legume, Florigraze rhizoma peanut (FRP), was used as the source of fiber to produce sugars. FRP was subjected to several ammonia-processing conditions using temperature, biomass moisture content, and ammonia loading as process variables during a 5-min treatment. A cellulase loading of 2 FPU/g DM and 24 h incubation were used to produce the sugars. Total sugar yield was 3.34-fold higher in the optimal treatment (1.5 g ammonia/g DM-60%-90°C) compared to untreated and was 65.3% of theoretical. Cellulose and hemicellulose conversions increased from 30 and 15.5% in untreated FRP to 78 and 34% in treated FRP.     

Synthesis of 2-alkyl-6-phenyl-3, 4-c cycloheptenopyrylium salts

A method is given for synthesizing 2-alkyl-6-phenyl-3, 4-cycloheptenopyrylium perchlorates, obtained in 45–55% yields by acylating cycloheptenylacetophenone with anhydrides of aliphatic acids in the presence of 70% perchloric acid. Treatment of the pyrylium salts with ammonia gives a good yield of 2-alkyl-6-phenyl -3, 4-cycloheptenopyridine.     

The Betti base: the awakening of a sleeping beauty

The multicomponent reaction between 2-naphthol, aryl aldehydes and ammonia or amines yields aminobenzylnaphthols in a process known as the Betti reaction, which was first uncovered at the beginning of the 20th century. The aminobenzylnaphthols could be easily resolved into their enantiomers. After a long silence, the results of our research a decade ago on this useful reaction and on the chiral materials produced has stimulated further work in a number of other laboratories. As a result, novel applications of the Betti reaction to produce new chiral aminobenzylnaphthols were reported together with the evaluation of these chiral bases in asymmetric synthesis. Herein, we present a selection of the relevant studies on this topic.     

3-取代和3,4-二取代噻吩的合成与表征

以噻吩、48% (m/m)氢溴酸水溶液、35% (m/m)过氧化氢水溶液、高纯氨、金属钠为原料合成了3-溴噻吩和3,4-二溴噻吩,3-溴噻吩和3,4-二溴噻吩分别以(dppp)NiCl2为催化剂合成了3-烷基噻吩和3,4-二烷基噻吩.3-溴噻吩以CuI, NaHSO4为催化剂合成了3-烷氧基噻吩,产率较高.并用核磁共振谱、质谱和元素分析方法进行了表征.     

Chemoselective reductive alkylation of ammonia with carbonyl compounds: synthesis of primary and symmetrical secondary amines

An efficient, general procedure for highly chemoselective reductive mono-alkylation of ammonia with ketones is reported. Treatment of ketones with ammonia in ethanol and titanium(IV) isopropoxide, followed by in situ sodium borohydride reduction, and a straightforward workup afforded primary amines in good to excellent yields. Reductive alkylation of ammonia with aldehydes, on the other hand, afforded the corresponding symmetrical secondary amines selectively.     

Enantioselective iridium-catalyzed allylic amination of ammonia and convenient ammonia surrogates

Iridium-catalyzed, asymmetric allylation of ammonia as a nucleophile occurs with stereoselectivity to form a symmetric diallylamine, and related allylation of the inexpensive ammonia equivalent potassium trifluoroacetamide or the highly reactive ammonia equivalent lithium di-tert-butyliminodicarboxylate forms a range of conveniently protected, primary, alpha-branched allylic amines in high yields, high branched-to-linear regioselectivities, and high enantiomeric excess. The reactions of ammonia equivalents were conducted with a catalyst generated from a phosphoramidite containing a single stereochemical element.     

顶空气相色谱法快速测定污水中氨氮含量

研究了一种基于化学反应型顶空气相色谱的快速检测污水氨氮含量新方法。首先在顶空瓶中用过量的甲醛与NH₄⁺反应产生等物质的量的强酸，再用NaHCO₃与新生成的酸反应产生CO₂，最后经过气相色谱定量CO₂，间接得出样品中氨氮的含量。结果表明，氨氮含量与气相色谱信号值之间存在良好的线性相关性，相关系数为0.999，定量限为0.786 mg/L（以N的质量浓度计），相对标准偏差小于2%，加标回收率在95%~105%之间。与国标纳氏试剂法相比，该方法测定结果的相对偏差在±5%以内。该方法检测效率高，适用于快速批量检测污水中氨氮的含量。