A-Halogen fatty acids

Related to the Grignard synthesis is that of Reformatzky in which zinc is used to condense the esters of a-halogenated fatty acids with ketones, e.g. ... 

Reaction XLIII. (c) Condensation of a-Halogen Fatty Acid Esters with Aldehydes and Ketones by means of Zinc or Magnesium (Reformatsky-Grignard). (C., (1901), I., 1196 II., 30 (1902), I., 856.)—This is an extension of the Grignard and zinc alkyl reactions which enables a-halogen esters to be condensed with carbonyl compounds as if they were simple alkyl halogen compounds. The zinc or magnesium alkyl derivative is neither prepared beforehand nor isolated in the reaction, but there is little doubt that some such compound is transitorily formed. Zinc is the metal... 

Aliphatic nitro compounds may be obtained in the well known Kolbe reaction [197] by acting with sodium nitrate on a- halogen fatty acids. During the substitution the carboxyl group splits off. 

In the preparation of a-halogen fatty acids phosphorus is used as a catalyst. It is assumed that the phosphorus forms the halide which acts on the acid to form the acyl halide ... 

The lack of an easily removable amino-protecting group led Fischer to the idea of introducing a-halogen fatty acid chlorides. These were coupled to the free amino group of the partner, the a-halogen fatty-acyl compound formed was reacted with ammonia to yield a new aminoacyl terminus [10]. 

Carbovy Alkylation with a-Halogen Fatty Acids. Rapkine (138) found that the SH groups of proteins reacted with iodoacetate in neutral or slightly alkaline solution, just as Dickens (139) had reported for reduced glutathione. 

A/-Chloro fatty acid amides have been synthesized from the direct halogenation of the amide in boiling water (28). They are useful as reactive intermediates for further synthesis. Fluorination has also been reported by treating the fatty amide with fluorine-containing acid reagents at 200 °C to reach a fluorinated amide with less reactivity toward fluorocarbon polymers (29). 

Reaction XLVm. (a) Action of Alkali Cyanides on Alkyl and Acyl Halides. (Bl., [2], 50, 214.)—This reaction is capable of very wide application, all the simple alkyl halogen compounds, the acyl halides, and the halogen fatty acids come within its scope. The nitriles so formed yield acids by hydrolysis, so it is frequently the first step in the synthesis of an acid—the preparation and hydrolysis of the nitrile are often combined. The preparations of malonic, succinic, tricarballylic and other acids (Preparations 60, 61, 62) illustrate this. The extension of this reaction to acyl halides is important, and should be referred to, as should the interaction of silver cyanide, and alkyl iodides, to give isonitriles. Mercuric and silver cyanides, it may be noted, give with acyl chlorides and bromides better yields of normal acyl nitriles than do the alkali cyanides. 

Rogozinskii [84] proposed the use of Verzamide 900 (polyamide resin) for subtracting compounds with an active halogen atom such as haloalkanes, aromatic halo compounds and ethers of a-bromo fatty acids. 

Other a-halogenated compounds have been used with equal success. These include iodoacetamide (140,144,141, 34,68,32), iodo ethyl alcohol (143), a brom fatty acids, and benzyl and phenyl ethyl halides (142). All react with certain SH groups of proteins at pH 7.0-9.0 and physiological temperatures. The iodoacetamide is somewhat more reactive than iodoacetate (144). Both iodoacetate and the corresponding amide were found to react fairly rapidly with p3rridine, even at pH 6.9 and 30 C. (145). Anson and Stanley (68) have reported that after almost complete inactivation of tobacco mosaic virus with iodoacetamide they could detect little, if any, drop in the number of SH groups. This calls for further study. 

N-Benzylamides are recommended when the corresponding acid is liquid and/or water-soluble so that it cannot itself serve as a derivative. Phe benzylamides derived from the simple fatty acids or their esters are not altogether satisfactory (see Table below) those derived from most hydroxy-acids and from poly basic acids or their esters are formed in good yield and are easily purified. The esters of aromatic acids yield satisfactory derivatives but the method must compete with the equally simple process of hydrolysis and precipitation of the free acid, an obvious derivative when the acid is a solid. The procedure fails with esters of keto, sul phonic, inorganic and some halogenated aliphatic esters. 

Bromination of fatty acids in the a-position can be effected quite readily in the presence of phosphorus trichloride, red phosphorus or pyridine as catalysts or halogen carriers with acetic acid, the addition of acetic anhydride (to ensure the absence of water) improves the yield and facilitates the bromination. Examples are —... 

Iodine monochloride [7790-99-0] ICl, mol wt 162.38, 78.16% I, is a black crystalline soHd or a reddish brown Hquid. SoHd ICl exists ia two crystalline modifications the a-form, as stable mby-red needles, d = 3.86 g/mL and mp 27.3°C and as metastable brownish red platelets, d = 3.66 g/mL, mp 13.9°C and bp 100°C (dec). Iodine monochloride is used as a halogenation catalyst and as an analytical reagent (Wij s solution) to determine iodine values of fats and oils (see Fats and fatty oils). ICl is prepared by direct reaction of iodine and Hquid chlorine. Aqueous solutions ate obtained by treating a suspension of iodine ia moderately strong hydrochloric acid with chlorine gas or iodic acid (118,119). 

Commercial cmde lecithin is a brown to light yeUow fatty substance with a Hquid to plastic consistency. Its density is 0.97 g/mL (Uquid) and 0.5 g/mL (granule). The color is dependent on its origin, process conditions, and whether it is unbleached, bleached, or filtered. Its consistency is deterrnined chiefly by its oil, free fatty acid, and moisture content. Properly refined lecithin has practically no odor and has a bland taste. It is soluble in aflphatic and aromatic hydrocarbons, including the halogenated hydrocarbons however, it is only partially soluble in aflphatic alcohols (Table 5). Pure phosphatidylcholine is soluble in ethanol. 

Reactions of the hydrocarbon chain in alkanoic acids include a-sulfonation and halogenation (51—54). The a-sulfonated fatty ester salts have excellent lime-dispersing properties and are valuable surface-active agents. 

Read over the entire activity. Form a hypothesis about how a change in color of a halogen can be used to predict the degree of saturation of a fatty acid. Record your hypothesis in the next column. 

In this work, halogens were added across the double bonds of unsaturated fatty acids (commercial available sunflower oil) to form addition compounds and the degree of uptake was measured. A measured excess of iodine monobrontide (IBr) was allowed to react with the oil in the dark. At the end of a timed period, an excess of K1 was added to convert the remaining IBr to The 1 formed was then titrated with standard thiosulfate. This was a back-titration method. A back-titration blank was also required, where the sample was omitted. The uptake of iodine was calculated... 

It is evident in this case that the velocity of reaction is not dependent on the energy of activation alone. This as we have seen is due to the fact that catalysis is not proceeding over the whole area of the catalyst but only at highly localised patches which in the case of palladium are evidently much more extensive than on duroglass. The energy of activation is calculated from the influence of temperature on the reaction velocity proceeding at an unknown area of surface whilst in the case of the combination of ethylene and the halogens it was tacitly assumed that a surface covered with molten fatty acids or alcohols would in all cases exhibit a... 

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