New unsaturated derivatives of Xanthan gum: Synthesis and characterization

Unsaturated Xanthan derivatives, which can be used for the development of biodegradable three-dimensional networks having hydrogel properties, were prepared by esterification under various conditions. Xanthan gum derivatives with different degrees of substitution were obtained by reaction with an unsaturated organic acid (acrylic acid) or with acid reactive derivatives (acryloyl chloride, maleic anhydride). The presence of acrylate and maleate groups in the modified structure of Xanthan gum was detected by ATR-FTIR, ¹H liquid NMR and ¹H HRMAS NMR spectroscopies. The degree of substitution as determined by ¹H NMR could be controlled by varying the chemical nature of functionalisation agent, reaction time and temperature.The results proved that this polysaccharide can be modified by esterification with acids or unsaturated acid derivatives for further synthesis of hydrogels. Maleic anhydride presents a higher reactivity as compared to acrylic acid and acryloyl chloride.     

Synthesis and polymerization of new vinyl derivatives of thymine

N-acryloyl and N-methacryloyl derivatives of thymine were prepared by one-step reaction of silylated thymine with acryloyl chloride and methacryloyl chloride, respectively, in good yields. These vinyl monomers containing thymines were polymerized and copolymerized with water soluble vinyl monomers such as acrylamide and vinylpyrrolidone by free-radical polymerization. Complex formation between copolymers and RNA in aqueous solution was studied by means of UV spectroscopy.     

On the polymerization of acrylonitrile in the presence of some unsaturated triazine derivatives

The polymerization of acrylonitrile in the presence of some unsaturated, triazinebased fluorescent brighteners (FB) has been investigated. It was found colourimetrically that more than 80% of the FB is incorporated in the polymer. The initial concentration of 0.1 wt.-% is sufficient to obtain a good bleaching effect without significant decrease of the molecular weight.     

微波辐射合成百里香酚的研究

以间甲酚为原料,在微波辐射下与异丙醇通过付克-烷基化反应生成了百里香酚,探讨了反应工艺条件,并采用GC-MS、IR和1H NMR等手段对产物进行了表征。结果表明,在微波辐射下,使用固体超强酸SO_4^(2-)/ZrO_2-TiO_2为催化剂,n(间甲酚)∶n(异丙醇)=1∶5,反应时间15 min,催化剂用量为原料间甲酚质量的8%,微波功率600 W,回流温度条件下百里香酚得率为59.2%。     

微波辐射合成百里香酚的研究

以间甲酚为原料,在微波辐射下与异丙醇通过付克-烷基化反应生成了百里香酚,探讨了反应工艺条件,并采用GC-MS、IR和1H NMR等手段对产物进行了表征。结果表明,在微波辐射下,使用固体超强酸SO_4~(2-)/ZrO_2-TiO_2为催化剂,n(间甲酚)∶n(异丙醇)=1∶5,反应时间15 min,催化剂用量为原料间甲酚质量的8%,微波功率600 W,回流温度条件下百里香酚得率为59.2%。     

Synthesis and polymerization of γ-ethyl-L-glutamate derivatives of nucleic acid bases

Summary -Ethyl-L-glutamate derivatives having pendant nucleic acid bases, that is, uracil, adenine and theophylline were synthesized. The -ethyl-L-glutamate having theophylline moiety was polymerized by using the N-carboxyamino acid anhydride (NCA) method.     

Step-growth polymerization of unsaturated aldehydes with diaminodiphenylmethane

Step-growth polymerization of diaminodiphenylmethane and unsaturated aldehydes (crotonaldehyde, cinnamaldehyde) proceeded easily in toluene at reflux temperature. Resins with molecular weights up to 1,500 g/mol were formed. In the first step of the reaction, the amino and the aldehyde groups reaction were predominate while the double bonds dominated to a lesser extent. The portion of unreacted monomers was under one percent. The resins consisted of oligomers with -CHNH-, -CH=N-, and -CH=CH-groups, which further reacted to form highly crosslinked resins. Kinetic data, the heat of the addition, the heat of condensation, and the activation energy were calculated. Faculty of Chemistry and Chemical Technology, Askerceva 5, 1001 Ljubjana, P.O.B. 537, Slovenia.     

Step-growth polymerization of guanamines with unsaturated aldehydes

Summary In acid medium and at temperatures from 50 to 100°C the resins from three different guanamines and three different unsaturated aldehydes were synthesized. The products were red coloured resins, which were soluble in organic solvents and were able to cure with hexamethylenetetramine to form hard and almost insoluble products. Using a combination of NMR and GPC methods it was possible to predict the course and the mechanism of the reactions. The rates of the reactions depend on the reaction conditions and on the type of the monomer.     

Oxidative polymerization of para-substituted styrene derivatives: Synthesis,characterization and kinetics study

Synthesis and characterization of four new polymeric peroxides of styrene monomers with substituents in the para-position are discussed. NMR spectroscopy and elemental analysis confirm the alternating copolymer structure with peroxy bonds in the backbone. The thermal degradation of the polyperoxides has been studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The measured highly exothermic heat of degradation of these polymers is nearly the same as that of poly(styrene peroxide). Electron-impact mass spectroscopy (EI-MS) supports alternating peroxide units in the polymer chain. Kinetics of oxidative polymerizations have been studied for various para-substituted styrene monomers in toluene in the presence of a free radical initiator 2,2′-azobisisobutyronitrile (AIBN) at 40–50 °C and 100 psi oxygen pressure. Interestingly, both electron-withdrawing and electron-donating substituent groups in the para-position increases rate of oxidative polymerization. Theoretical studies have been performed using density functional theory (DFT) to support the order of oxidation rates.     

Step-growth polymerization of unsaturated aldehydes with aliphatic amines

The step-growth polymerization of unsaturated aldehydes (acrolein, crotonaldehyde, cinnamaldehyde) and aliphatic amines (butylamine, ethylenediamine, triethylenetetramine, diethylenetriamine, hexamethylenediamine) took place intensively in the temperature range between 50 and 90°C. The rates of individual reactions depended on the type of individual aldehydes and amines. The quantity of individual unreacted monomers was mostly under 1%. The average molecular weights of oligomers were between 290 and 710. The individual resins consisted of oligomers with free ? OH, ? NH, ? CH?N? , and ? CH?CH? groups, which are further able to cross-link the resins with three blocked isocyanate to insoluble, elastic film with high adhesion to glass and metal substratum. © 1994 John Wiley & Sons, Inc.     

Synthesis of unsaturated aldehydes

Olealdehyde, linolealdehyde and stearolaldehyde were prepared from the corresponding acid chlorides by reduction with lithium tri-tert-butoxyhydroaluminate. Multiple bond location by means of ozonolysis techniques and determination of configuration of the double bond by spectral techniques indicate that this reaction proceeds without substantial bond migration orcis,trans isomerization. Presented at AOCS Meeting, Chicago, October, 1967. No. Utiliz. Res. Dev. Div., ARS, USDA.     

Role of unsaturated groups in glow discharge polymerization

The role of unsaturated groups of the starting compounds in glow discharge polymerization was investigated by elemental analysis, infrared spectroscopy, and ESCA. Tetramethylsilane (TMS), trimethylvinylsilane (TMVS), and ethyltrimethylsilane (ETMS) were used as starting materials. Glow discharge conditions (W/FM value meaning the rf power input per mass of the monomers) as well as a degree of the unsaturation of the starting materials had strong influences upon the polymer deposition rate and the elemental composition of the formed polymers. The C_1s and the Si_2p spectra showed that the chemical composition of these polymers was distinguished by either presence or absence of the unsaturated groups in the starting compounds rather than kind of the unsaturated groups. The polymer formation, when the monomers containing double and triple bonds were served, is proceeded not only through these unsaturated bonds but also through the cleavage between Si and C atoms.     

Hydrozirconation for unsaturated fatty acid derivatives

In the hydrozirconation reaction, developed by Schwartz and coworkers,bis(π-cyclopentadienyl) zirconium hydridochloride Cp₂-Zr(H)Cl, is added to the double bond of an olefin. The organozirconium intermediate can be functionalized by reaction with a variety of electrophiles such as oxygen, halogens, acetyl chloride and carbon monoxide. Furthermore, the double bond can be reformed by treatment with a hydride acceptor such as triphenylmethyl tetrafluoroborate. When a short-chain internal olefin is hydrozirconated, the initially formed alkylzirconium intermediate is rapidly isomerized to a compound in which the zirconium moiety is bound to the sterically least hindered position, which most often is the terminal position. The isomerization occurs rapidly at room temperature in contrast to the corresponding organoboron or aluminum compounds, which slowly positionally rearrange only at elevated temperatures. Because of the facile isomerization of internal alkylzirconium compounds to the terminal ones, we investigated application of the reaction to unsaturated fatty acids such as oleic and erucic acids. However, reactions on long-chain alkenes (such as oleic acid) are frequently much slower than those conducted on shorter-chain alkenes, and attention must be given to optimizing the reaction conditions if good yields are to be obtained. It would also be necessary to find an easily removable protecting group for the carboxylic function, as Cp₂Zr(H)Cl reduces carboxylic acids to alcohols. We found that the 4,4-dimethyl-2oxazoline function is a suitable protecting. group, and therefore synthesized the oxazolines from oleic acid and erucic acid. Hydrozirconation of the 4,4-dimethyl-2-oxazoline of oleic acid followed by oxidation witht-butyl hydroperoxide and conversion to methyl esters, gave methyl 3-hydroxy and methyl 18-hydroxy stearate in 13% and 17% yield, respectively. The relatively low yield is due to competing hydrogenation, the mechanism of which is discussed. Recent results indicate that the carboxyl group can be protected ast-butyl esters in the hydrozirconation and that oleyl alcohol derivatives can also be used. To understand the isomerization pattern in hydrozirconation, the reaction with α,β- and β,γ-unsaturated fatty acid oxazolines is discussed. Possibilities of making the hydrozirconation reaction catalytic by binding of the hydrozirconation reagent to a solid support as well as the synthetic potential in combining hydrozirconation with the olefin metathesis reaction are briefly reviewed.     

Synthesis of polymers having arylene-vinylene units by palladium-catalyzed hydroarylation polymerization of diethynylbenzene derivatives

Summary Arylene-vinylene-containing polymers with fully aromatic backbone structures were prepared by the palladium-catalyzed hydroarylation polymerization of diethynylbenzene derivatives with diiodobenzene and alkylmalonate anions as a hydride source. For instance, the polymerization of 1,4-bis(4'-dodecyloxy)phenylethynylenebenzene, diiodobenzene, and sodium diethyl benzylmalonate was carried out at 80°C for 2 days in 1,4-dioxane in the presence of Pd(OAc)₂ / tri-o-tolylphosphine (7 equiv. to Pd) to produce a polymer (M _n= 6,390, M _w/M _n= 1.53) in high yield (86 %). Using various diethynylbenzene derivatives, polymers having arylene-vinylene units were also obtained in high yields. Received: 16 December 1999/Accepted: 20 January 2000     

固体不饱和聚酯树脂的合成工艺

采用二步熔融缩聚法制得了固体不饱和聚酯树脂(UP),研究了UP的不饱和酸含量、醇酸比及合成反应温度、反应时间对反应的影响,并通过物理力学性能测试及耐热性测试研究了不同原料配比的UP产物对粉末涂料涂膜和粘结永磁塑料性能的影响。结果表明,适用于粉末涂料和粘结永磁塑料的UP树脂原料乙二醇、对苯二甲酸与反丁烯二酸的物质的量配比分别为2.1∶1∶1和2.42∶1∶1.3。适合的反应温度为210～220℃,反应时间8 h。     

Synthesis of unsaturated epoxyfumarate resins

One- and two-step procedure syntheses of epoxyfumarate resins are presented. In the two-step procedure, acidic ester of maleic acid was synthesized separately and then used for the addition reaction with epoxy resin, Epidian 5. In the one-step procedure, synthesis acidic ester was formed during the synthesis process. Properties of the resins obtained in the one- and two-step procedures, in a noncrosslinked state during curing and after crosslinking, were compared. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1423–1429, 1998     

Heavily brominated and highly unsaturated derivatives of jojoba oil

Two hexabromojojoba isomers were prepared by bromine addition to bromo-olefinic and bromoallylic derivatives, and an octabromojojoba derivative was prepared from jojobatetraene. Bis-allylic bromination of jojoba wax or monoallylic bromination of jojobatetraene, both followed by HBr elimination, yielded jojobahexaene, which has two conjugated triene units on both parts of the ester. Bromine addition to jojobahexaene yielded dodecabromojojoba, which was unstable toward hydrolysis in water-decalin mixture at 120C., This is in contrast to the relative stability of the octabromojojoba under these conditions. This paper is the fifth in a series of functionalization at the double bond region of jojoba oil.     

Synthesis and properties of unsaturated epoxyfumarate resins

Synthesis and properties of epoxyfumarate and epoxymaleate resins obtained by the addition of acidic ester of maleic acid to the commercially available resin, Epidian 5, is presented. In acidic ester preparation, n‐hexanol was used. The resins were synthesized in one‐ and two‐step procedures. In the two‐step procedure, acidic hexyl maleate was synthesized separately and then used for the addition reaction with epoxy resin. In the one‐step synthesis, acidic ester was formed during the synthesis process. Properties of the obtained resins were compared. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 3077–3084, 2000