scholarly journals Revisiting the condensation reaction of lignin in alkaline pulping with quantitativity part I: the simplest condensation between vanillyl alcohol and creosol under soda cooking conditions

2021 ◽  
Vol 67 (1) ◽  
Author(s):  
Toshihiro Komatsu ◽  
Tomoya Yokoyama
Keyword(s):  
Hplc Analysis ◽  
Condensation Product ◽  
Condensation Reaction ◽  
Model System ◽  
The Self ◽  
Vanillyl Alcohol ◽  
Condensation Products ◽  
Alkaline Pulping ◽  
Reaction Solution ◽  
Cooking Conditions

AbstractThe condensation reaction of lignin is believed to interfere with delignification in alkaline pulping processes, without any clear evidence, which has motivated us to quantitatively revisit it. This paper is the first of a series, and hence we employed the simplest model system using 4-hydroxymethyl-2-methoxyphenol (vanillyl alcohol, Va) and 2-methoxy-4-methylphenol (creosol, Cr) under soda cooking conditions. The α-5-type condensation product between these compounds [VaCr, 2-(4-hydroxy-3-methoxybenzyl)-6-methoxy-4-methylphenol] was identified and quantified as exclusive. VaCr was yielded with a mole amount of 24%, 46%, 62%, or 72% based on that of disappearing Va at a reaction time of 120 min when the ratio of the initial concentration of Cr to that of Va was 1.0, 2.5, 5.0, or 7.5, respectively. These yields and an HPLC analysis of the reaction solution obtained by a treatment of Va as the sole compound under the same soda cooking conditions suggested the formation of self-condensation products of Va even in the treatments containing Cr. The obtained results comprehensively suggested that the self-condensation of Va progresses more readily than the condensation between Va and Cr. The factors behind this will be the topic of our next paper.

The self-condensation reaction of lithium ester enolates. Isolation of a ketene intermediate

1977 ◽  
Vol 42 (11) ◽  
pp. 2038-2039 ◽  
Author(s):  
Donald F. Sullivan ◽  
Richard P. Woodbury ◽  
Michael W. Rathke
Keyword(s):  
Condensation Reaction ◽  
The Self

STUDIES ON LIGNIN AND RELATED COMPOUNDS: XVI. PHENOL LIGNIN FROM SPRUCE WOOD, FROM FREUDENBERG SPRUCE LIGNIN AND WILLSTÄTTER SPRUCE LIGNIN

1935 ◽  
Vol 13b (2) ◽  
pp. 61-77 ◽  
Author(s):  
Irene Koerber Buckland ◽  
Fritz Brauns ◽  
Harold Hibbert
Keyword(s):  
Condensation Product ◽  
Analytical Data ◽  
Insoluble Fraction ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Condensation Products ◽  
Building Unit ◽  
Spruce Wood ◽  
Analytical Results ◽  
The Difference

The condensation of lignin with phenol by treatment of spruce wood meal with this solvent, using hydrogen chloride as catalyst, yields two chemically different phenol lignins, namely, an ether-insoluble and an ether-dioxane–soluble phenol lignin, in a ratio of approximately 3 to 1. Duplicate preparations gave the same yields of these two fractions, analyses of which gave concordant results, indicating homogeneity and constancy of composition.The analytical results of the ether-insoluble phenol lignin, and of its methylated and acetylated derivatives, can be interpreted on the basis of the Brauns–Hibbert formula for the "native" lignin unit. It is found, in this way, that the ether-insoluble phenol lignin contains three new free phenolic hydroxyl groups capable of methylation with diazomethane, while one phenol group has reacted with one hydroxyl group in the lignin unit with formation of a phenyl-oxygen ether linkage.The analytical results of the ether-dioxane–soluble phenol lignin indicate that a much larger quantity of phenol has condensed with the "native" lignin building unit than in the case of the ether-insoluble fraction. The exact number of phenol molecules reacting to form this condensation product has not been determined experimentally although calculations based on analytical data point to a number as large as 15 or 21.The phenol condensation products were obtained from Freudenberg and Willstätter lignins in nearly quantitative yield and found to differ from the directly extracted phenol lignin in that neither of them could be resolved into two fractions, thus indicating that some change had taken place in the native lignin during the isolation process. The Brauns-Hibbert formula can also be applied to interpret the experimental data in both cases. These lignins appear to contain the same fundamental building unit as the ether-insoluble phenol lignin fraction isolated directly from spruce wood, with the difference that the former probably have one additional hydroxyl group capable of acetylation and diazomethane-methylation.The correlation found to exist in the present investigation between the phenol condensation products from native spruce lignin, isolated Freudenberg lignin and Willstätter lignin is regarded as providing definite experimental evidence indicating the presence of a chemical unit common to various lignins. The phenol condensation products, it is considered, may serve as valuable reference compounds for proving the identity of lignins obtained from different sources and by use of different chemical reagents.

scholarly journals Studies on Ketene and Its Derivatives. XXVI. The Structure of the Self-condensation Product of Acetoacetamide (Supplement)

1968 ◽  
Vol 16 (9) ◽  
pp. 1835-1837 ◽  
Author(s):  
TETSUZO KATO ◽  
HIROSHI YAMANAKA ◽  
JUNSHI KAWAMATA ◽  
TETSUICHI SHIBATA
Keyword(s):  
Condensation Product ◽  
The Self

New Condensation Products of Rubber Hydrocarbons by the Aid of Benzyl Chloride

1932 ◽  
Vol 5 (2) ◽  
pp. 110-116
Author(s):  
F. Kirchhof
Keyword(s):  
Aluminum Chloride ◽  
Benzyl Chloride ◽  
Condensation Product ◽  
Chemical Properties ◽  
Metal Chlorides ◽  
Condensation Products ◽  
New Type ◽  
The One ◽  
Physical And Chemical ◽  
And Chemical Properties

Abstract The application of the long-known Friedel-Crafts reaction to rubber hydrocarbons led to a new type of condensation products which may be called provisionally aral cyclorubbers (“benzylidene rubbers”), since their benzylidene groups are probably condensed with the polyprene skeleton to cyclic systems. It would not have been foreseen without further work that rubber would form this type of condensation product with aral halides in the presence of aluminum chloride, since on the one hand benzyl chloride is known to form, by the action of aluminum chloride in the Friedel-Crafts reaction, an amorphous, apparently high molecular hydrocarbon of the empirical composition (C7H6)x, and on the other hand rubber in solution is transformed by the metal chlorides, especially aluminum chloride, into amorphous polycyclorubbers. Under definite conditions of condensation with aluminum chloride aral groups are combined with the skeleton of the rubber hydrocarbon with the formation of white to yellowish amorphous bodies which contain, in addition to a small proportion of organically combined chlorine, only carbon and hydrogen, and are therefore to be regarded as hydrocarbons. In their physical and chemical properties these substances resemble the already known amorphous substance of the empirical formula (C7H6)x, which doubtless is polybenzylidene, probably hexabenzylidene.

The Discussion on Synthesis Process of Biurea by Hydrochloric Acid

2013 ◽  
Vol 448-453 ◽  
pp. 464-467 ◽  
Author(s):  
Meng Meng Qi ◽  
Ran Guo ◽  
Meng Su ◽  
Xiao Xue Cheng ◽  
Ling Zhang
Keyword(s):  
Hydrochloric Acid ◽  
Hydrazine Hydrate ◽  
Ph Value ◽  
Condensation Reaction ◽  
Complex Salt ◽  
Synthesis Process ◽  
Optimum Process ◽  
Process Conditions ◽  
Acid Method ◽  
Reaction Solution

By Series of comparative experiments, Factors of influencing the yield of biurea which is prepared from the condensation reaction between hydrazine hydrate and urea are studied, such as pH value, ratio of urea to hydrazine hydrate, temperature of reaction solution, reaction time and acid addition order. Under the optimum process conditions, the yield of biurea can reach over 97%, the biurea produced by hydrochloric acid method avoids large amounts of complex salt wastewater in condensation reaction of sulfuric acid method, and make the production process of biurea tends to be more environmentally friendly.

STUDIES ON LIGNIN AND RELATED COMPOUNDS: XV. PHENOL GLYCOL LIGNIN

1935 ◽  
Vol 13b (1) ◽  
pp. 55-60
Author(s):  
Fritz Brauns ◽  
Harold Hibbert
Keyword(s):  
Condensation Product ◽  
Hydroxyl Groups ◽  
Nuclear Condensation ◽  
Condensation Products ◽  
Related Compounds

Phenol condensation products of glycol lignin, of a premethylated and a fully methylated glycol lignin have been prepared. In each case it has been found that, on the basis of the five methoxyl groups present in the original glycol lignin, three molecules of phenol react with one lignin unit by nuclear condensation, and when the product is worked up immediately no loss of methoxyl groups occurs. With the fully methylated glycol lignin in one experiment, some of the methoxyl groups were removed but the hydroxyl groups thus formed could not be remethylated with diazomethane, thus indicating their probable aliphatic character. Quercetin does not give a phenol condensation product under the same conditions.

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