The oxidation of the aldehyde groups in dialdehyde starch

This paper describes the difference in relative reactivity of the aldehyde groups present in dialdehyde starch towards different oxidising agents. The oxidation of dialdehyde starch with peracetic acid and sodium bromide leads to only partial oxidation to give mono-aldehyde-carboxy starch, while oxidation with sodium chlorite results in...

Selective oxidation of polysaccharides, a tool for carbohydrate-based alternatives for Carbopol®

Improved calcium sequestering carbohydrate based agents

The improved tandem oxidation sequence of starch with the aim of developing, e.g. degradable co-builders suitable for laundry formulations as an alternative to the currently used polyacrylates is described. The tandem oxidation of starch starts with sodium periodate treatment of granular starch followed by oxidation of the dialdehyde product...

Methods for the Selective Oxidation of Cellulose: Preparation of 2,3-Dicarboxycellulose and 6-Carboxycellulose

Three methods for the selective oxidation of cellulose are described. The classical method consists of consecutive oxidation with sodium periodate, leading to 2,3-dialdehyde cellulose and sodium chlorite, giving 2,3-dicarboxy cellulose. This material, which is obtained in high yield and has a high carboxylate content (7.6 mmol COONa/g; 90% of...

Method for preparation of a calcium-binding polydicarboxy-inulin and its use as replacement for phosphates in detergents

Superabsorbent material and method for producing said material

On the use of stable organic nitroxyl radicals for the oxidation of primary and secondary alcohols

This article reviews the oxidation of primary and secondary alcohols using nitroxyl radicals from the first publication in which this reaction was described in 1965. A variety of stoichiometric and catalytic methods is discussed, with reactions in organic solvents, under biphasic conditions as well as in water. Mechanistic studies and general...

Calcium sequestering agents based on carbohydrates

Present-day West-European builder systems in detergent formulations often consist of zeolite NaA together with a synthetic polycarboxylate. The latter materials are nonbiodegradable and substitutes should be considered. Carbohydrates seem attractive raw materials in this respect, since carboxylate groups that are essential for calcium binding in...

TEMPO-mediated oxidation of pullulan and influence of ionic strength and linear charge density on the dimensions of the obtained polyelectrolyte chains

The applied pH during the TEMPO-mediated (2,2,6,6-tetramethylpiperidine-1-oxyl) oxidation of the polysaccharide pullulan has a substantial influence on the molar mass distribution of the products. The least degradation was found in the pH range 9.2-9.7 and especially at higher pH, significant degradation occurs due to β-elimination. Four samples...

Highly selective nitroxyl radical-mediated oxidation of primary alcohol groups in water-soluble glucans

With catalytic amounts of 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) and hypochlorite/bromide as the regenerating oxidant in water, primary alcohol groups in glucans and derivatives thereof were rapidly and completely oxidised. For pyranosides, selectivity was higher than 95% and no side products could be detected with 1H and 13C NMR or with...

Selective oxidation of primary alcohols mediated by nitroxyl radical in aqueous solution. Kinetics and mechanism

The kinetics of the TEMPO-mediated oxidation of methyl α-D- glucopyranoside to sodium methyl α-D-glucopyranosiduronate were studied. An intermediate was found which was identified as the hydrated aldehyde. This was oxidised in the same manner as the alcohol, with pseudo first order rate constants ratio k(obs,ald)/k(obs,alc) = 7. The reaction...

The relation between calcium sequestering capacity and oxidation degree of dicarboxy-starch and dicarboxy-inulin

Enzymatic synthesis of hydroxymethylfurfural esters

The bromide-catalyzed hypochlorite oxidation of starch and inulin: calcium complexation of oxidized fructans

Omzetting van koolhydraten

The leachability of carbon-14-labelled 3,4-benzopyrene from coal ash into aqueous systems

The leachability of polycyclic aromatic hydrocarbons from coal ash into aqueous systems was studied. Carbon-14-labeled 3,4-Benzopyrene (BaP) was deposited on coal fly ash by adsorption from the liquid phase in quantities of about 10 ??g/g ash. After a thermal treatment in air at 120??C for 2 hours the desorption of BaP was measured using aqueous...

Formation of chemical compounds from irradiated mixtures of aromatic hydrocarbons and nitrogen oxides

The paper describes the analysis of products of the photochemical degradation of toluene and toluene-14C in smog chamber experiments. Compounds identified included methylglyoxal, possibly the recently postulated butenedial and other carbonyl compounds. The main product of photochemical degradation of methylglyoxal appeared to be acetaldehyde....

Synthesis of beta-sitosterol-3-14C ( β‐sitosterol‐3‐14C )

The synthesis of β‐sitosterol‐3‐14C, specific activity 5 mCi/mM, radiochemical purity ≥98 %, is described. Starting from stigmasterol, the complete synthesis consists of eleven reaction steps. It is based on methods described in the literature. For some of the steps, a considerable improvement in yield has been achieved. The actual labelling...