The Mechanism of the Alkali catalysed Phenol-Formaldehyde reaction

1955 ◽  
Vol 8 (2) ◽  
pp. 194 ◽  
Author(s):  
JS Fitzgerald ◽  
RJL Martin
Keyword(s):  
Induction Period ◽  
Aldol Condensation ◽  
Phenol Formaldehyde ◽  
Kinetic Studies ◽  
Bimolecular Reaction ◽  
Hydrogen Ion ◽  
Catalysed Reaction ◽  
Alkaline Reaction ◽  
Cannizzaro Reaction ◽  
Mechanism Of The Reaction

Kinetic studies on the 2,3,4,5-tetramethylphenol(prehnitenol)- and 2,6-xylenol-formaldehyde reactions indicate that the alkali catalysed reaction is not a simple bimolecular reaction. The rate of the 2,6-xylenol-formaldehyde reaction in the presence of excess alkali has been shown to be proportional to [phenoxide]1.4 [formaldehyde]1.4 [free alkali]-0.4. The mechanism of the reaction has been interpreted as a reaction between the phenoxide ion and CH2=O together with other simultaneous reactions. It is unlikely that the +CH2OH plays any part in the alkali catalysed reaction. Attempts have been made to interpret the results on the basis that a hemiformal rearranges to a phenol alcohol and that the ion +CH2OPh reacts with a phenoxide ion. In any case it is not possible to give a complete mechanism with certainty. The degree of formation of hemiformal is too small to be detected by hydrogen ion measurements. When the Cannizzaro reaction of formaldehyde is carried out in the presence of a phenol, the phenoxide Ions catalyse a condensation which 1s presumably an aldol condensation. This reaction having a long induction period and being autocatalytic does not assume importance In the early stages of the reaction. A compound, probably 2,2'-dihydroxy-3,3',4,4',5,5',6,6'-octamethyldiphenylmethane, has been isolated from the alkaline reaction between prehnitenol and formaldehyde.

scholarly journals Secondary organic material formed by methylglyoxal in aqueous aerosol mimics

2010 ◽  
Vol 10 (3) ◽  
pp. 997-1016 ◽  
Author(s):  
N. Sareen ◽  
A. N. Schwier ◽  
E. L. Shapiro ◽  
D. Mitroo ◽  
V. F. McNeill
Keyword(s):  
Organic Material ◽  
Aldol Condensation ◽  
Bimolecular Reaction ◽  
Ionization Mass ◽  
Aerosol Formation ◽  
Hydronium Ion ◽  
Rate Limiting Step ◽  
Tropospheric Aerosol ◽  
Heterogeneous Processes ◽  
Rate Limiting

Abstract. We show that methylglyoxal forms light-absorbing secondary organic material in aqueous ammonium sulfate and ammonium nitrate solutions mimicking tropospheric aerosol particles. The kinetics were characterized using UV-Vis spectrophotometry. The results suggest that the bimolecular reaction of methylglyoxal with an ammonium or hydronium ion is the rate-limiting step for the formation of light-absorbing species, with kNH4+II=5×10−6 M−1 min−1 and kH3O+II≤10−3 M−1 min−1. Evidence of aldol condensation products and oligomeric species up to 759 amu was found using chemical ionization mass spectrometry with a volatilization flow tube inlet (Aerosol-CIMS). Tentative identifications of carbon-nitrogen species and a sulfur-containing compound were also made using Aerosol-CIMS. Aqueous solutions of methylglyoxal, with and without inorganic salts, exhibit significant surface tension depression. These observations add to the growing body of evidence that dicarbonyl compounds may form secondary organic material in the aerosol aqueous phase, and that secondary organic aerosol formation via heterogeneous processes may affect seed aerosol properties.

scholarly journals Kinetics and proposed mechanism of the reaction of an immunoinhibition, particle-enhanced immunoassay

1997 ◽  
Vol 43 (12) ◽  
pp. 2384-2389 ◽  
Author(s):  
John C Thompson ◽  
Alan R Craig ◽  
Carol L Davey ◽  
David J Newman ◽  
Michele L Lonsdale ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Maximum Rate ◽  
Colloidal Stability ◽  
Kinetic Studies ◽  
Latex Agglutination ◽  
Equivalence Point ◽  
Colloidal Aggregation ◽  
Free Sample ◽  
Identical Fashion ◽  
Mechanism Of The Reaction

Abstract We report kinetic studies on the reaction of a latex agglutination immunoassay used to quantify phenytoin in serum. In this assay, polystyrene particles with a covalently attached analog of phenytoin react with an antiphenytoin monoclonal antibody to form light-scattering aggregates, with the rate of this reaction being decreased by addition of phenytoin from sample. In the absence of free (sample) phenytoin, this reaction did not exhibit a maximum rate of agglutination in the presence of excess antibody, i.e., an equivalence point. Furthermore, agglutination was inhibitable by free phenytoin even when the latter was added after agglutination of particles with antibody had begun. Most significantly, the immunoagglutination proceeded in an identical fashion with monovalent F(ab) fragment. These data are consistent with low-affinity immunospecific particle–antibody complexation, which then induces colloidal aggregation, without requiring immunospecific bridging by antibody molecules. The described mechanism is not generalizable to all latex agglutination immunoassays, although disturbance of colloidal stability may be a component in most assays.

scholarly journals The reaction between aluminium metal and aqueous solutions of the nitrite ion

1980 ◽  
Vol 33 (1) ◽  
pp. 169 ◽  
Author(s):  
PJ Hyde ◽  
IM Ritchie
Keyword(s):  
Aqueous Solutions ◽  
Induction Period ◽  
Sodium Nitrite ◽  
Room Temperature ◽  
Nitrite Ion ◽  
Aluminium Metal ◽  
Mechanism Of The Reaction

The reaction between aluminium metal and a 0.1 wt % solution of sodium nitrite at room temperature is described. Initially the reaction is slow, but after an induction period the aluminium corrodes catastrophically. The products of the reaction were identified as ammonia, hydrogen and bayerite. A possible mechanism of the reaction is suggested.

scholarly journals Investigation of the structure and mechanism of the reaction of synthesis of monoalkyl(C8-C12) phenolformaldehyde oligomers modified by imidazolines based on natural petroleum acids and polyamines using method of IR-spectroscopy

2019 ◽  
pp. 16-19
Author(s):  
M. N. Amiraslanova ◽  
N. R. Abdullayeva ◽  
L. I. Aliyeva ◽  
R. A. Rustamov ◽  
S. F. Akhmedbekova ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Ir Spectroscopy ◽  
Ir Spectra ◽  
Phenol Formaldehyde ◽  
Mechanism Of The Reaction

The structures of novolac monoalkyl(C8-C12)phenol-formaldehyde oligomers, modified with imidazolines based on natural petroleum acids and polyamines-diethylenetriamine, triethylenetetraamine, polyethylenepolyamines were investigated by IR-spectroscopy. As a result of the analysis of the IR-spectra of the initial and final products, the reaction mechanism is proposed.

N-Heterocyclic Carbene-Catalyzed Synthesis of Ynones via C–H Alkynylation of Aldehydes with Alkynyliodonium Salts

2019 ◽  
Author(s):  
Adam A. Rajkiewicz ◽  
Natalia Wojciechowska ◽  
Marcin Kalek
Keyword(s):  
Density Functional ◽  
Bond Formation ◽  
Kinetic Studies ◽  
Density Functional Theory Calculations ◽  
Hypervalent Iodine ◽  
Functional Theory ◽  
Leaving Group ◽  
13C Labelling ◽  
Reaction Proceeds ◽  
Mechanism Of The Reaction

Alkynylation of aldehydes with alkynyl(aryl)iodonium salts catalyzed by an N-heterocyclic carbene (NHC) has been developed. The application of the organocatalyst and the hypervalent iodine group-transfer reagent allowed for metal-free C–H functionalization and C–C bond formation. The reaction proceeds under exceptionally mild conditions, at –40 ⁰C and in the presence of an amine base, providing access to an array of heteroaryl-propargyl ketones containing various substituents in good to excellent yields. The mechanism of the reaction was investigated by means of both experiments and density functional theory calculations. 13C-labelling and computations determined that the key alkynyl transfer step occurs via an unusual direct SN2 substitution of iodine-based leaving group by Breslow intermediate nucleophile at an acetylenic carbon. Moreover, kinetic studies revealed that the turnover-limiting step of the catalytic cycle is the generation of the Breslow intermediate, whereas the subsequent C–C bond-formation is a fast process. These results were fully reproduced and rationalized by the computed full free energy profile of the reaction, showing that the largest energy span is located between protonated NHC and the transition state for the carbene attack on the aldehyde substrate.<br>

The mechanism of the Cannizzaro reaction of Formaldehyde

1954 ◽  
Vol 7 (4) ◽  
pp. 335 ◽  
Author(s):  
RJL Martin
Keyword(s):  
Fourth Order ◽  
Kinetic Data ◽  
Order Reaction ◽  
Rate Equations ◽  
Third Order ◽  
The Third ◽  
Hydride Ion ◽  
Cannizzaro Reaction ◽  
Wide Range ◽  
Mechanism Of The Reaction

For a wide range of concentrations of formaldehyde and alkali, the Cannizzaro reaction of formaldehyde can be described as the sum of a third and a fourth order reaction. However, the concentrations which are used for the rate equations must be corrected for the amount of methylene glycol anion present. The dissociation constant of methylene glycol as determined from the kinetic data is the same magnitude as that derived electrometrically. The mechanism of the reaction is interpreted as a reaction between formaldehyde and the hydride ion donors CH2(O-)(OH) and CH2(O-)(O-) It is shown why the third order reaction proposed by previous workers is not always applicable.

Titanium and zirconium ferrocene-substituted enolates and their reaction products with benzaldehyde and acetophenone: structural and kinetic studies of the aldol condensation pathway

1995 ◽  
Vol 14 (9) ◽  
pp. 4101-4108 ◽  
Author(s):  
Patrick Veya ◽  
Pier Giorgio Cozzi ◽  
Carlo Floriani ◽  
Francois P. Rotzinger ◽  
Angiola Chiesi-Villa ◽  
...  
Keyword(s):  
Aldol Condensation ◽  
Kinetic Studies ◽  
Reaction Products

The Chemistry of Sugar-Cane Wax. I. The Nature of Sugar-Cane Wax

1960 ◽  
Vol 13 (2) ◽  
pp. 261 ◽  
Author(s):  
JA Lamberton ◽  
AH Redcliffe
Keyword(s):  
Sugar Cane ◽  
Aldol Condensation ◽  
Conclusive Evidence ◽  
High Yield ◽  
Reduced Pressure ◽  
Polymeric Form ◽  
Cannizzaro Reaction ◽  
Long Chain

Distillation of sugar-cane cuticle wax under reduced pressure gives a high yield of long-chain aldehydes, which are considered to occur in the wax in polymeric form. The products obtained from the wax under normal saponification conditions are apparently produced from the aldehydes by a Cannizzaro reaction, and by aldol condensation with subsequent dehydration. The cuticle wax also contains hydrocarbons and free alcohols and acids, but there is no conclusive evidence for the presence of esters.

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