Ultrasound in fatty acid chemistry: Synthesis of a 1-pyrroline fatty acid ester isomer from methyl ricinoleate

A novel 1-pyrroline fatty acid ester isomer [viz. 8-(5-hexyl-1-pyrrolin-2-yl)octanoate] has been synthesized from methyl ricinoleate by two routes with an overall yield of 42 and 30%, respectively. Most of the reactions are carried out under concomitant ultrasonic irradiation (20 KHz,ca. 53 watts/cm²). Under such a reaction condition, the reaction time is considerably shortened, and product yields are high. Dehydrobromination under concomitant ultrasonic irradiation of methyl 9,10-dibromo-12-hydroxyoctadecanoate with KOH in EtOH furnishes methyl 12-hydroxy-9-octadecynoate (66%) within 15 min. Hydration of the latter under ultrasound with mercury(II)acetate in aqueous tetrahydrofuran yields exclusively methyl 12-hydroxy-9-oxo-octadecanoate (95%) in 30 min. The hydroxy group in the latter compound is transformed to the azido functionvia the mesylate, and treatment of the azido-oxo intermediate (methyl 12-azido-9-oxooctadecanoate) with Ph₃P under ultrasonic irradiation furnishes the requisite 1-pyrroline fatty acid ester (77%). The same azido-oxo intermediate has also been obtained by the oxidation of methyl 12-azido-9-cis-octadecenoate using benzoquinone and a catalytic amount of Pd(II)chloride in aqueous tetrahydrofuran under concomitant ultrasonic irradiation (90 min) to give the product in 45% yield. The latter reaction does not take place even under prolonged silent stirring of the reaction mixture.     

超声辐射下合成盐酸罗哌卡因

在超声辐射下,以(S)-2-哌啶甲酸(Ⅱ)为原料,依次与氯化亚砜、2,6-二甲基苯胺反应制得(S)-N-(2,6-二甲基苯基)-2-哌啶甲酰胺(Ⅴ),而后,Ⅴ与溴丙烷发生N-丙基化反应,经盐酸成盐得到目标化合物手性纯的盐酸盐罗哌卡因(Ⅰ)。该文考察了超声辐射条件下反应溶剂、反应温度和反应时间等因素对反应收率的影响。优化后的工艺条件与传统加热方法相比,具有条件温和、反应时间短、收率高等优点。得到的最佳反应条件为:以甲苯为酰氯和酰胺反应溶剂,酰氯化反应条件为40℃超声反应1.5 h,丙基化反应条件为40℃超声反应1 h,盐酸罗哌卡因的收率为57.8%,[α]2D5=-6.7°(c2,H2O)。部分中间体和目标产物的结构通过熔点和核磁共振波谱进行了表征。     

Degradation and in situ reaction of polyolefin elastomers in the melt state induced by ultrasonic irradiation

The degradation and in situ reaction with polystyrene (PS) of polyolefin elastomers in the melt state induced through high intensity ultrasonic wave were investigated. The effects of initial molecular weight of polyolefin elastomers, irradiation time, ultrasonic intensity, as well as reaction temperature on the ultrasonic degradation of polyolefin elastomers melt were studied using a “static” ultrasonic vibration system. The results show that the degradation occurs mostly at the tip of the ultrasonic probe, and little or no degradation was observed at the distance of 5 mm or greater from the tip of the probe. The intrinsic viscosity [η] of polyolefin elastomers near the tip of ultrasound probe significantly decreases with irradiation time in the first 100 s and tends toward a limiting value for all samples. The degradation rates increased with an increase in ultrasonic intensity and decrease in reaction temperature. The ultrasonic degradation kinetics of polyolefin elastomers in melt state follows the equation: [η]_t = [η]_∞ + Ae^?kt. The fitting results by this equation accord well with the experimental data. The feasible ultrasonic degradation mechanism is proposed based on the viscoelastic characteristic of polymer melt. FTIR analysis confirms that the copolymer forms under ultrasonic irradiation for PS/POE mixtures and in situ reaction of polymer in melt state can be induced by ultrasonic irradiation. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Reaction of amines with conjugated olefins using lithium naphthalenide in non-ethereal solvents

It was found that lithium naphthalenide can be prepared from metallic lithium cuttings and naphthalene in non-ethereal solvents, such as benzene–N,N,N′,N′-tetramethylethylenediamine (TMEDA) or benzene-N,N,N′,N′-tetramethyldiaminopropane (TMDAP), under ultrasonic irradiation. Secondary amines reacted with conjugated olefins, such as isoprene or myrcene, using lithium naphthalenide in such non-ethereal solvents to give allylic amines. The yields of products were higher than in the reaction using lithium naphthalenide in tetrahydrofuran. From diethylamine (I) and isoprene (II), a mixture of N,N-diethyl-3-methyl-2-butenylamine (IV) and N,N-diethyl-2-methyl-2-butenylamine (V) (IV:V = 79:21) was obtained in 77% yield, and from diethylamine (I) and myrcene (III), N,N-diethylgeranylamine (VI) and N,N-diethylnerylamine (VII) (VI:VII = 88:12) were produced in 72% yield. These terpenic amines, VI and VII, are used as starting compounds for the preparation of perfumery materials.     

Modification of polypropylene with maleic anhydride: Ultrasonic irradiation effects

The mechanochemical reaction of modificated of polypropylene (PP) with maleic anhydride (MAH) has been studied by ultrasonic irradiation as an energy source at 60°C. Through 2³ factorial experimental design, three variables and their interactions were studied: the percentage of MAH, the percentage of benzoyl peroxide (BPO), and ultrasonic irradiation intensity (Watts). According to the results, an increase of wt % of MAH gave a negative effect in the grafting yield; in addition, this negative effect was observed in the interaction of MAH : BPO at a high range of wt %, this behavior is attributed to the homopolymerization of MAH at the experimental conditions employed. The higher positive effect onto the grafting yield was observed for the variable watts (ultrasonic irradiation intensity), even at low intensity. The better interaction of variables gave a MAH grafting degree of 4.65 wt % (93% yield). In addition, the effect of ultrasonic irradiation on the number-average molar mass (M_n), weight-average molar mass (M_w), and polydispersity index (M_w/M_n) was measured. It was observed that the M_w decreased 13.73% and the M_w/M_n also decreased by 11.98%. The o observed effect was attributed to the degradation mechanism induced by the ultrasound, which consists in the generation of macroradicals and their recombination. The product PP-g-MAH was characterized by infrared spectroscopy, also was used to prepare polypropylene–nylon-6 blends. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68:45–52, 1998     

Surface Treatment of ZrO2 Nanoparticles with Biosafe Citric Acid and Its Utilization for the Synthesis of L-leucine Based Poly(Amide–Imide) Nanocomposites

This study aimed at preparing three nanocomposites of optically active poly(amide–imide) and zirconium dioxide (ZrO₂) inorganic nanoparticles through the ultrasonic process. First, the surface of ZrO₂ nanocomposites was chemically modified with bio-active citric acid in the basic media. Then, the poly(amide–imide) was reinforced with modified nanocomposites and three poly(amide–imide)/ZrO₂-citric acid nanocomposites were synthesized by ultrasonic irradiation. The poly(amide–imide) was prepared by polycondensation of N-trimellitylimido-L-leucine with 4,4′-diaminodiphenylsulfone using of triphenyl phosphite and molten tetra-n-butylammonium bromide as green media. The obtained poly(amide–imide)/ZrO₂-citric acid nanocomposites were characterized by different techniques.     

A facile one pot synthesis of some new 2-phenyl-2H-[1,3]thiazino[6,5-b]quinolines under microwave irradiation in solvent free conditions

A series of some new 2-phenyl-2H-[1,3]thiazino[6,5-b]quinolines have been synthesized by the one pot reaction between 2-chloro-3-formylquinolines 1a–i and thiobenzamide using p-TsOH catalyst under microwave irradiation. The procedure is simple, environmentally benign and occurs in good yields. All the new compounds were characterized by elemental analyses, IR, ¹H NMR and mass spectral data.     

醋酸铵催化合成香豆素-3-羧酸乙酯的工艺研究

以水杨醛和丙二酸二乙酯为原料,醋酸铵为催化剂,采用超声波技术搅拌,在无溶剂条件下,经Knoevenagel缩合反应,合成香豆素-3-羧酸乙酯,其结构经IR表征。考察了超声波辐射时间、原料配比、催化剂的用量等对反应的影响。结果表明,最优条件为：超声波功率100W、超声时间10min、加热反应时间90min、水杨醛与丙二酸二乙酯的物质的量比为1∶1.60、水杨醛与催化剂的物质的量比为1∶1.50。在优化条件下,香豆素-3-羧酸乙酯的收率为89.8%。与常规合成方法相比,该合成方法具有操作简单、收率高、环境友好等特点。     

超声波辐射下草酸催化合成3,4-二氢嘧啶-2(1H)-酮

采用草酸为催化剂,由醛、1,3-二羰基化合物和脲(硫脲)在无溶剂超声波辐射下,简单有效地合成了标题化合物.和传统方法相比,该方法具有反应时间短(<1.5 h)、收率高(78%～92%)、分离简单等优点.     

Ultrasound accelerated sulfonylation of amines by p-acetamidobenzenesulfonyl chloride using Mg–Al hydrotalcite as an efficient green base catalyst

The sulfonylation reaction of various aliphatic, alicyclic, aromatic, and hetero-aromatic amines with p-acetamidobenzenesulfonyl chloride has been investigated using different types of base catalysis under varied reaction conditions. Mg–Al hydrotalcite, characterizable as an inexpensive, reusable, and green solid catalyst, was found to be the most efficient catalyst, when the reaction is carried out in a minimum volume of solvent (acetone). The reaction was found to be accelerated drastically with the support of ultrasound irradiation, affording the sulfonamides in yields better or equivalent to those obtained under the longer lasting conventional stirring conditions.     

Structure and thermal stability of polysaccharide fractions extracted from the ultrasonic irradiated and cold alkali pretreated bamboo

Polysaccharide fractions were extracted from partially delignified bamboo (Neosinocalamus affinis) culms pretreated with ultrasonic irradiation for varied times and cold sodium hydroxide/urea solution, and their structure and thermal stability were comparatively characterized. In this case, ball‐milled bamboo culms were treated with ultrasonic irradiation for varied times (0, 5, 15, and 25 min), dissolved with 7% sodium hydroxide/12% urea solution at −12°C, and then extracted with ethanol and dioxane to obtain partially delignified solid fractions. Subsequently, the solid fractions were subjected to be extracted with dimethyl sulfoxide followed by precipitation in ethanol and yielded the polysaccharide fractions. Sugar analysis indicated that the total sugar content increased from 60.63% in the polysaccharide fraction prepared without ultrasonic irradiation to 81.26% in the polysaccharide fraction prepared with an ultrasonic irradiation time of 25 min. Glucose (∼ 50–55%) was the major sugar component, and xylose (∼ 41–44%) was the second major sugar in polysaccharide fractions in all cases. Spectroscopy (FTIR, ¹H‐NMR, ¹³C‐NMR, and HSQC) analysis suggested that the polysaccharide fractions were mainly composed of (1→4)‐linked α‐D ‐glucan from amylose and (1→4)‐linked β‐D ‐xylan attached with minor amounts of branched sugars from hemicelluloses. In addition, thermal analysis showed that the main degradation stage of the polysaccharide fractions occurred between 210 and 320°C. Compared to the polysaccharide fraction prepared without ultrasonic irradiation, the polysaccharide fraction prepared with ultrasonic irradiation had a slightly lower thermal stability. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Fast and efficient green synthesis of thiosulfonate S-esters by microwave-supported permanganate oxidation of symmetrical disulfides

Potassium permanganate absorbed on copper(II) sulfate pentahydrate has been found to be an efficient, inexpensive, and green oxidation agent for the synthesis of “symmetrical” thiosulfonate S-esters by oxidation of the corresponding symmetrical disulfides. The oxidation reactions were carried out under solvent-free reaction conditions within 15?min under the influence of microwave irradiation, as well as (for comparison) supported by conventional heating, to afford yields of the thiosulfonate S-esters in the range of 60–83%. The oxidation reaction appears to proceed (at least partly) via an intermediate symmetrical vic-disulfoxide.     

Mechanochemical synthesis and characterization of poly(vinyl chloride) -block- poly(acrylonitrile-co-butadiene) copolymers by ultrasonic irradiation

Summary Mechanical degradation and mechanochemical reaction in heterogeneous and homogeneous systems of poly(vinyl chloride) and poly(acrylonitrile-co-butadiene) polymer have been studied by ultrasonic irradiation at 30 °C. The rates of decrease in the number-average molecular weights of the degraded poly(vinyl chloride) and poly(acrylonitrile-co-butadiene) polymer in the swelled poly(vinyl chloride) — poly(acrylonitrile-co-butadiene) polymer solution were much faster than the homogeneous solution system and the final average chain lengths led to the smaller values than those in the latter system. On the other hand, mechanochemical reaction occurred by polymer radicals produced from the chain scissions of both polymers by ultrasonic irradiation. The changes in the composition of the total block copolymer, the unreacted poly(vinyl chloride), and the unreacted poly(acrylonitrile-co-butadiene) polymer in both reaction systems were obtained. Received: 4 September 2001/Accepted: 22 October 2001     

Reaction of arylidenehydrazono-4-aryl-2,3-dihydrothiazole-5-carbonitriles with diethyl acetylenedicarboxylate. Synthesis of (Z)-ethyl 2-[((Z)-2-(E)-arylidenehydrazono)-4-oxo-thiazolidine-5-ylidene]acetates. NMR investigation

(Z)-Ethyl 2-[((Z)-2-(E)-arylidenehydrazono)-4-oxo-thiazolidine-5-ylidene]acetates were synthesized by three different methods: (a) reaction of arylidenehydrazono-4-aryl-2,3-dihydrothiazole-5-carbonitriles with diethyl acetylenedicarboxylate (DEAD) in acetic acid with prolonged reflux, (b) reaction between thiosemicarbazones, 2-arylidenemalononitriles and DEAD under conventional conditions or microwave irradiation, (c) one-pot three-component reaction of thiosemicarbazone derivatives, ylidene and DEAD. The thiazolinone adducts were obtained in good to excellent yields. NMR of the obtained products was investigated.     

Highly efficient and scale-up synthesis of propargylamines catalyzed by graphene oxide-supported CuCl2 catalyst under microwave condition

An efficient, green and practical approach was developed to synthesize propargylamines using recyclable GO-CuCl₂ via a one-pot multicomponent aldehyde–alkyne–amine (A³) coupling reaction. The propargylamines are readily obtained in good to excellent yields (85–96%) and on multi-gram scale (88%, 150 mmol) under microwave irradiation. GO-CuCl₂ could be easily recovered through filtration and reused at least five recycles with no significant decreases in the yields.     

Effect of ultrasonic irradiation on ceric‐salt‐initiated grafting of methyl methacrylate onto regenerated cellulose film

Effect of ultrasonic irradiation on ceric salt (Ce⁴⁺)‐initiated grafting of methyl methacrylate (MMA) on regenerated cellulose film (thickness = 20 μm) was investigated under an air atmosphere in water solvent at 60°C. The grafting system with the ultrasonic irradiation was characterized by higher percentage of grafting and graft efficiency than the system without the irradiation. Reaction of cellulose with Ce⁴⁺ was also accelerated by the ultrasonic irradiation. No accelerating effect of grafting due to the ultrasonic irradiation was observed for the system under reduced pressure of 5 torr. The effect of the ultrasonic irradiation on the average molecular weight of MMA‐grafted chains was also studied. Moreover, the surface layer of the resulting grafted films was examined by attenuated total reflection–infrared (ATR–IR) measurement and scanning electron microscopy (SEM) observation. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 251–258, 1999     

Synthesis of polyethylene using ultrasonic energy with a metallocene catalyst

Ethylene polymer was synthesized by the treatment of a metallocene catalyst Zr(CP)₂Cl₂ solution with ultrasonic energy. Ultrasonic energy irradiation was used to change the polymer structure of the formed polymer. Different ultrasonic energy irradiation times were applied to the metallocene catalyst solution. The ultrasonic energy had an effect on the average molecular weight, molecular weight distribution, and polymer productivity. A lower average molecular weight and a narrower molecular weight distribution were produced with a longer ultrasonic irradiation time. The polymer productivity was almost constant when the metallocene catalyst was treated with ultrasonic energy. Finer polyethylene particles were produced with longer ultrasonic irradiation times. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 756–759, 2006     

Extraction of Essential Oils From the Seeds of Pomegranate Using Organic Solvents and Supercritical CO2

In this study, essential oils from pomegranate seeds of the Malas variety from Shahreza, Iran, were extracted using hexane and petroleum benzene applying four extraction methods: normal stirring, soxhlet, microwave irradiation, and ultrasonic irradiation. Also, supercritical fluid extraction (SFE) using CO₂ under different conditions was used for comparison. Different methods of extraction with organic solvents (normal stirring, soxhlet, microwave irradiation, and ultrasonic irradiation) showed significant differences in the extraction yields. However, no differences were found when a given method (e.g., microwave irradiation) was applied using different organic solvents. On the other hand, different extraction conditions from the various runs of SFE resulted in different extraction yields, all of which were lower than those of the other extraction methods using organic solvents. No significant differences were observed in the fatty acid compositions of the extracted oils using organic solvents. However, the fatty acid compositions of the oils extracted under different conditions of the SFE system indicated significant differences among several fatty acids including unsaturated fatty acids.     

Ultrasonic mixing and closed microwave irradiation-assisted transesterification of soybean oil

The present study employed ultrasonic mixing and closed microwave irradiation to assist transesterification of soybean oil. The purpose was to obtain the optimal ultrasonic mixing and closed microwave irradiation procedure. The optimal reaction conditions including amount of catalyst used, reaction temperature and methanol/oil molar ratio were also investigated to achieve the highest possible conversion rate of biodiesel. Results showed that the optimal procedure involved 1-min ultrasonic mixing and 2-min closed microwave irradiation. The optimal reaction conditions that can reach 97.7% of conversion rate were amount of catalyst used, 1.0 wt%; reaction temperature, 333 K; and methanol/oil molar ratio, 6:1.     

超声波辐射条件下锡(Ⅱ)催化合成二吲哚基甲烷的方法研究

研究了一种由Sn Cl2催化合成二吲哚基甲烷的高效方法。引用超声波辐射作为反应条件,在反应体系中加入当量的催化剂能够在短时间内合成出二吲哚基甲烷且分离方法简单易行。合成出的系列二吲哚基甲烷具有一定的光学性质,即在400~600 nm波长范围内范围内具有光吸收作用,且在受波长为370 nm光的激发下,会发出波长约为440 nm的紫光。