Study of the condensation products of abietic acid with formaldehyde

Abietic acid and paraformaldehyde, taken in various molar ratios, were condensed in acid catalysis (p-toluenesulfonic acid). Toluene was used both as reaction medium and carrier for aqueous condensate. The obtained polymeric products (resins) were characterized by determination of acid number, melting point, molecular weight and viscosity. Spectral methods, e.g. I. R. and ¹H-NMR, were also used in the same scope. The experimental data evidence the fact that abietic acid is a substance with a functionality of minimum 3 as against formaldehyde. There have been obtained some condensation products with three-dimensional structure and low molecular weight. The polymerization average degree of the resins was found to be 3, although some fractions with polymerization average degree of 6 have been observed. The chemical bonds established between the structural units can be of both methylenic and dimethylene ether type, depending on the molar ratio of reacting substances.     

Anodic oxidation of 2,6-xylenol in acetonitrile on platinum

Anodic oxidation of 2,6-xylenol at the platinum electrode in acetonitrile was investigated by the various electrochemical and chemical methods. Conductivity measurements indicated that the phenolic hydroxyl of 2,6-xylenol is undissociated in acetonitrile solution containing lithium perchlorate. By cyclic voltammetry and chronopotentiometry, it was shown that anodic oxidation of 2,6-xylenol at the platinum electrode proceeds in two steps. 2 electrons are involved in the first step, as determined by cyclic voltammetry using hydroquinone and DPPH as a reference compound. Polarographic study suggested that the first step is an electrophilic attack on the aromatic nucleus of the non-ionized phenol. The electrolysis products were analysed by thin-layer chromatography, ir and uv spectrophotometry and mass spectrometry. It is estimated that dimer, trimer and tetramer are produced by the anodic oxidation of 2,6-xylenol and that the dimer is 2,2′-dihydroxyl-3,3′-dimethylstilbene. The formation reactions of trimer and tetramer probably proceed by the same mechanism as dimer formation.     

苯酚甲醇气相烷基化合成2,6-二甲酚

采用共沉淀法制备了Fe系复合催化剂,考察了该催化剂对苯酚-甲醇气相烷基化合成2,6-二甲酚的催化性能。实验结果表明,在0.2MPa、反应温度340℃,液态空速0.5 h-1,苯酚∶甲醇∶水=1∶5∶0.5(mol/mol)的反应条件下,苯酚单程转化率达99%,2,6-二甲酚选择性85%以上,邻位总选择性在98%以上。催化剂制备简单,再生容易,重复性好。     

The quantitative analysis of the polyester components of crosslinked silicone-polyester-aminoformaldehyde condensation products

Analysis of normally hydrolysis-resistant polymers, including silicone-polyesters, have recently been reported. Here we extend these methods to the analysis of condensation products of silicone-polyester resins and conventional butylated aminoplasts. Crosslinked systems employing butylated derivatives of urea-formaldehyde, melamine-formaldehyde and benzogaunamine have been degraded using an acetic acid-acetic anhydride reagent. Simultaneous hydrolysis of the polyester components and cleavage of both the ether crosslinks and the butoxy groups of the aminoplast occurred. Reaction conditions were also established where urea-formaldehyde, when used as a crosslinking agent, is simultaneously degraded using the same reagent.

While the products were first examined as crosslinked condensation products, the procedures are also applicable to precondensation mixtures of the polyesters and the aminoplasts. The methods are suitable for quality control procedures.     

分段导数分析法用于苯胺甲醛缩合反应过程综合

苯胺甲醛缩合制多胺的反应是典型的第Ⅲ类反应体系,反应过程复杂。针对反应的阶段性特征,采用分段导数分析法对其进行反应器网络综合,第一阶段应采用DSR或PFR;第二阶段应采用PFR。采用不同的流程结构进行试验,结果为：采用DSR+PFR的流程结构,最终产品中二氨基二苯甲烷（MDA）含量最高;采用PFR+PFR的流程结构,最终产品中二氨基二苯甲烷（MDA）含量次之。试验结果与导数分析法分析结果一致,表明本文所用方法是有效的。     

Homogeneously catalyzed condensation of formaldehyde to carbohydrates: VI. Preparation and spectroscopic investigation of complexes active in formaldehyde condensation

Condensation of formaldehyde (formose reaction) is catalyzed by complexes between alkaline earth metal hydroxides and carbohydrates, formed in situ in an autocatalytic reaction. When prepared externally and isolated, the complexes of Ca(OH)₂ with glucose and dihydroxyacetone show catalytic activities very similar to those of equivalent quantities of their components added separately to the reaction mixture. Spectroscopic (ESCA, ir) and gc data point to formation of a loosely structured and dynamic mixture of species, bonded as coordinated adducts (rather than discrete highly polarized compounds) between the alkaline earth metal hydroxide and carbohydrates. The sugars and Cannizzaro reaction products that form by condensation of HCHO in D₂O show no CD bonds, indicating that the aqueous solvent does not participate in the formose reaction. Sugar formation from HCHO occurs within the complex.     

The chemistry of lauric acid-diethanolamine condensation products

Summary The reaction of lauric acid with diethanolamine in the presence of excess alkylolamine results initially in the formation of N,N′-bis(2-hydroxyethyl)lauramide. This compound is responsible for the surface-active properties of the alkanolamides. Under the conditions of the reaction the amide undergoes a thermal rearrangement to the lauroyl ester of diethanolamine, which in turn is converted to the dilauroyl amido ester of diethanolamine. The excess diethanolamine converts both amino ester and amido ester to N,N′-bis(2-hydroxyethyl)lauramide.     

The acid catalysed condensation of phenol-4-sulphonic acid with formaldehyde

The reaction products formed when phenol-4-sulphonic acid reacts with formaldehyde have been investigated using ¹H and ¹³C nuclear magnetic resonance. It is shown that the reaction does not proceed readily at high phenol-4-sulphonic acid: formaldehyde ratios. As the ratio is decreased evidence of reaction is observed and further decreases lead to crosslinking. The crosslinking reaction is explained in terms of desulphonation and electrophilic substitution of the sulphonic acid group by a hydroxymethylene carbonium ion.     

The use of gel permeation chromatography to study the condensation of resorcinol with formaldehyde

Gel permeation chromatography has been used to study the acid-catalysed condensation of resorcinol with formaldehyde in concentrated solution. Rate curves for the consumption of resorcinol and the formation of some of the oligomeric products, and changes in molecular weight distribution during the reaction have been compared for condensates prepared using various reaction conditions.     

A photographic study of condensation in the presence of instabilities

A photographic study has been carried out to illustrate the behaviour and appearance of thin films in the presence of instabilities. Such information i     

Crosslinking of gelatin with formaldehyde in the presence of some poly-hydroxybenzenes

The crosslinking of gelatin by formaldehyde in the presence of some poly-hydroxybenzenes was studied. Model substances in which gelatin was replaced by amino acids and short peptides were prepared. The UV-spectra of solutions of these substances show a striking resemblance to those obtained with crosslinked gelatin. From the IR-spectra and analytical data of the model substances structural formula were deduced. The most defined structure was established for a condensation product in which the molar ratio phloroglucinol-glycine-formaldehyde was 1:2:6. The reactions are 1. a Mannich type, and 2. a resol type in which the link is a dimethylene ether bridge. The crosslinking reaction with gelatin seems to occur in the same way.     

Reaction of formaldehyde with cellulose in the presence of phosphoric acid

The extent and rate of reaction between cotton yarn before and after slack mercerization and slack mercerization followed by restretching and formaldehyde in the presence of various amounts of phosphoric acid (10–70% by weight) have been studied. The reaction is very rapid beyond a concentration of 45% phosphoric acid. The reaction has also been studied on mercerized cotton voile in the presence and absence of polyols and ammonium sulfate, and the effect of these substances on combined formaldehyde value and tensile strength of the fabric has been investigated.     

Reaction of formaldehyde with cellulose in the presence of sulfuric acid

The extent and rate of reaction between cotton yarn before and after slack mercerization and slack mercerization followed by stretching and formaldehyde, in the presence of various amounts of sulfuric acid (5–60% by weight) were studied. Beyond a concentration of 45% sulfuric acid, the reaction takes place very rapidly, and an explanation is put forward in terms of the extent of swelling of the fiber in sulfuric acid solutions. The reaction was also studied in the presence of glycerin, when the combined formaldehyde value is shown to decrease with an increasing concentration of glycerin.     

人造板及其制品甲醛释放量限量与室内甲醛污染

本文通过对国家强制性标准GB18581-2001《人造板及其制品甲醛释放量限量》中实木复合地板甲醛释放量的分析,揭示了室内甲醛污染超标的原因,对此强制性标准提出了改进的意见.     

双氰胺甲醛缩聚反应机理和强放热现象研究

在分析已有双氰胺甲醛缩聚反应机理的基础上,提出了一种新的反应机理,认为多个双氰胺分子可以通过氰基与胺基反应生成的亚胺基键而生成高分子聚合物,并通过键能计算证明该反应是一个放热反应,其反应放热量与试验中测得的升温温度相符,该机理可以合理地解释双氰胺甲醛缩聚物制备过程中剧烈的放热升温现象。     

Kinetics of the reaction between urea and formaldehyde in the presence of sulfuric acid

The kinetics of the reaction between urea and formaldehyde were studied in the presence of various amounts of sulfuric acid (5–45% by weight) at different temperatures (5°, 15°, and 25°C). The reaction was shown to follow first-order kinetics. The activation energy for the reaction varies from 12.51 kcal/mole to 14.59 kcal/mole in the range of sulfuric acid concentration studied.