Reduction by formaldehyde

A reduction by formaldehyde is involved in the first step of the preparation of p-dimethylaminobenzaldehyde (5) from p-nitrosodimethylaniline (1), dimethylaniline... 

In the diamine stains, the ammoniacal silver solution must be acidified, usually with citric acid, for image production to occur. The addition of citric acid lowers the concentration of free ammonium ions, thereby liberating silver ions to a level where their reduction by formaldehyde to metallic silver is possible. The optimal concentration of citric acid also results in a controlled rate of silver ion reduction, preventing a non-selactive deposition of si 1ver. 

Interestingly, true hydrides, such as NaH and KH, do not reduce carbonyl groups. Using energies of hydride and methoxide (at left), calculate AH xn for the reduction of formaldehyde by H. Is this reaction more or less favorable than those based on ZH4 Can the low reactivity of NaH and KH be attributed to thermodynamic factors, or must kinetic factors be responsible ... 

Eschweiler-Clarke modification org chem A modification of the Leuckart reaction, involving reductive alkylation of ammonia or amines (except tertiary amines) by formaldehyde and formic acid. esh,vTl-3r klark. mad-o-fo ka-shon ... 

Amine synthesis from reductive amination of a ketone and an amine in the presence of excess formic acid, which serves as the reducing reagent by delivering a hydride. When the ketone is replaced by formaldehyde, it becomes Eschweiler-Clarke reductive alkylation of amines. 

The resulting 2,6-xylidide a-pipecolinic acid (2.2.5) is methylated to mepivacaine using formaldehyde with simultaneous reduction by hydrogen in the presence of platinum on carbon catalyst [15]. 

Hydrochlorothiazide Hydrochlorothiazide, 1,1-dioxide 6-chloro-3,4-dihydro-2//-l,2,4-benzothiadiazin-7-sulfonamide (21.3.4), is synthesized either by cyclization of 4,6-sulfon-amido-3-chloroaniline (21.3.2) using paraformaldehyde, during which simultaneous reduction of the double bond occurs at position C3-C4, or the drag is synthesized by reduction of the same double bond in chlorothiazide (21.3.3) by formaldehyde. This small change in structure increases activity of the drag in comparison with chlorothiazide, and increases its absorbability when used orally [12-17]. 

This assumption of Pauly s was confirmed by Knoop and Windaus, who found that histidine is resistant to reduction by sodium and alcohol whereas the pyrimidine rii is very unstable towards this reagent. On reducing Frankel s oxydesaminohistidine, which is obtained from histidine by the action of nitrous acid, they obtained /8-imidazole-propionic acid. This compound was identical with the synthetical product prepared from glyoxylpropionic acid, ammonia and formaldehyde — ... 

CO formation on copper electrodes appears to be accompanied by hydride formation as well [103]. In Sch. 3, the surface bound CO is reduced by a hydride transfer reaction to form a formyl species as shown in step 2. There are precedents in organometallic chemistry for late transition metal hydrides reducing bound CO [105-109]. Protonation of the adsorbed formyl in step 3 results in the formation of a hydroxy carbene species [110, 111]. This hydroxycarbene species could be considered to be an adsorbed and rearranged form of formaldehyde, and the reduction of formaldehyde at a copper electrode has been reported to form hydrocarbons [102]. However, reduction of... 

The original waste solution was comprised of mercuric chloride, mercury bound tissue, and, possibly, mercury metal. The metal may be a result of the reduction of mercuric chloride by formaldehyde.6 The varying proportions of mercury in these different forms cause the amount of mercury metal recovered to vary. The assumption is made that the process will have a recovery efficiency comparable to the efficiency in the electrolysis of the standard solution (60%). 

Observations also made by Foss et al. [65] showed that a certain amount of the nitrate (II) is produced during prolonged storage of hexamine dinitrate owing to partial decomposition followed by the reduction of formaldehyde to a methyl radical. 

It is obvious that OH determination cannot serve as sole evidence to judge the reactivity of lignin with formaldehyde. While reduction by... 

This equation was used to calculate the reaction rates as a function of temperature and rongalite/Ni(II) concentration ratio, and Table 11.6 shows the results for a ratio of 1.5/0.5. The data in this table confirm the previous conclusion that a temperature of about 333 K should be used in order to have an economical and technologically acceptable reaction rate for the reduction of Ni(II) by rongalite and to avoid the large influence of autoinhibition by formaldehyde, an unfavourable effect that increases with temperature. 

ISO ISO DIS 16000-23 Performance test for evaluating the reduction of formaldehyde concentrations by sorptive building materials ... 

In the first attempt the tetracyclic intermediate (33) was prepared from 3,4-methylenedioxy-ta-nitrostyrene upon Diels-Alder addition of butadiene followed by zinc and hydrochloric acid reduction to an amine eventually converted into 33 by formaldehyde and hydrochloric acid. All other experiments, designed to anticipate the addition of a C6 diene (in order to introduce at once also the C2 carbon unit for ring D formation) or of a four-carbon diene with different functionality, failed. The structure of 33 is based on spectroscopic data, on considerations on the accepted stereochemical courses of this type of... 

Controlled growth of previously deposited very small silver particles can also be performed. The procedure involves to establish first the minimum temperature at which reduction of the metal proceeds in the bulk of the solution. With the reduction of silver ammine complexes by formaldehyde, the temperature to effect reduction in the bulk of the liquid is about 310K. It has been found that metallic silver particles catalyze the reduction of the silver ammine complexes. By suspension of a silica support covered with small silver particles in a solution of Ag(NH3)7 cooling the suspension to 273 K and subsequently injection of formaldehyde, controlled growth of the silver particles can be achieved. It is interesting that the silver particles... 

A classical example for a CE process is the reduction of formaldehyde to methanol, where the formaldehyde is formed by dehydration of methan-di-ol [i, ii] -> chemical reactions in electrochemistry, preceding reaction. 

Electroless plating — An autocatalytic process of metal deposition on a substrate by reduction of metal ions from solution without using an external source of electrons. It is promoted by specific reductants, namely formaldehyde, sodium hypophosphide, sodium boro-hydride, dialkylamine borane, and hydrazine. Electroless deposition has been used to produce different metal (e.g., nickel, cobalt, copper, gold, platinum, palladium, silver) and alloy coatings. It can be applied to any type of substrate including non-conductors. Some substrates are intrinsic catalytic for the electroless deposition other can be catalyzed usually by sensibilization followed by Pd nucleation also, in some non-catalytic metallic substrates the electroless process can be induced by an initial application of an appropriate potential pulse. In practical terms, the evaluation of the catalytic activity of a substrate for the electroless deposition of a given metal is... 

Basic Pd-C prepared from PdCl2 by reduction with formaldehyde and sodium hydroxide in the presence of active carbon. 

Platinum Triselenide, PtSe3, has been obtained as a black, flocculent precipitate by reduction with formaldehyde of a solution of an alkali chlor-platinate in the presence of a selenite and an excess of alkali.3... 

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