Formamides special

Finally, it s worth mentioning the formamide group. Although this looks like a special case of a secondary amide, rotamers of different intensity are often seen. Compounds with a formamide attached to an aromatic ring can give particularly complex spectra. Not only does the NH proton couple to the CHO proton, with a coupling of about 2-3 Hz in the cis isomer, and 8-9 Hz in the trans isomer, but, any aromatic protons ortho to the formamide are also split out in the rotamers ... 

Since sodium borohydride usually does not reduce the nitrile function it may be used for selective reductions of conjugated double bonds in oc,/l-un-saturated nitriles in fair to good yields [7069,1070]. In addition some special reagents were found effective for reducing carbon-carbon double bonds preferentially copper hydride prepared from cuprous bromide and sodium bis(2-methoxyethoxy)aluminum hydride [7766], magnesium in methanol [7767], zinc and zinc chloride in ethanol or isopropyl alcohol [7765], and triethylam-monium formate in dimethyl formamide [317]. Lithium aluminum hydride reduced 1-cyanocyclohexene at —15° to cyclohexanecarboxaldehyde and under normal conditions to aminomethylcyclohexane, both in 60% yields [777]. 

In this paper a generalized approach is presented to the derivation of H-H-S equations for multispecies polymers created by addition polymerization across single double bonds in the monomers. The special cases of copolymers and terpolymers are derived. This development is combined with experimental results to evaluate the numerical parameters in the equations for poly(styrene-acrylonitrile ) (SAN) in three separate solvents and for poly(styrene-maleic anhydride-methyl methacrylate) (S/HA/MM) in a single solvent. The three solvents in the case of SAN are dimethyl formamide (DMF), tetrahydrofuran (THF), and methyl ethyl ketone (MEK) and the solvent for S/HA/HH is HER. 

Dimethylformamide initiation is a special case. Polythiocarbonyl fluoride prepared with this initiator, as has been stated, also has all three possible ends with —SCF=0 being present in smallest amount. Also, the polymer as isolated is free of the formamide. It is here proposed that dimethylformamide initiation may proceed as follows ... 

Solid Mo02Br2(DMF)2 melts at 139-141°C with decomposition. The IR spectrum, taken as a KBr dispersion, has characteristic bands for i moO 903 and 940 cm The NMR spectrum in acetone-t/g exhibits signals at S 3.03 (s, 3H, CHa), 3.22 (s, 3H, CH3), 8.26 (s, IH, CH). The complex is insoluble in hexane and diethyl ether and is soluble in methanol, ethanol, dichloromethane, chloroform, acetone, dimethyl formamide, and dimethyl sulfoxide. It is stable in air at room temperature and can be manipulated without special care. This product is specially useful for the synthesis of a number of adducts with pyridine and related bases, since the dimethyl formamide displaced can be readily removed by washing with most common organic solvents. 

Fig. 10. Conversion-time curves for polymerisation of NCA s in 80% nitrobenzene —20% N-inethyi formamide mixture 26° C. [NCA] — 0.109 mol. I"1 Initially in all cases, (a) y-benzyl-L-gtutamate NCA [sodium dl-hydrocinnamate = 4.6 x 10 mol 1-J (b) DL-phenylalanineNCA [sodiumdihydrocinnamate] — 4.6 x 10 moll-1 (c) DL-phenylalanine NCA [sodiumhydantoin 3-acetate] = 9.2 x 10 moll-1. 100% evolution of CO . [Reprinted from paper by D. G. H. Ballard and C. H. Bamford Special Publication of Chem. Soc.

In the interests of improved electrochemical background limits and reactant stability, it is important to employ solvents that are as free as possible of nucleophiles and proton sources. Special attention always goes to the removal of water. The most important media are carefully purified acetonitrile, dimethyl-formamide, benzonitrile, and tetrahydrofuran. Popular supporting electrolytes are tetra-n-butylammonium perchlorate (TBAP) and fluoroborate (TBABF4). Solutions are usually prepared by vacuum-line methods (Chap. 18) or in a dry box (Chap. 19) to exclude oxygen from the systems and to avoid contamination by water. 

Digoxigenin-labeled chromosome 10 a-satellite probe (DIOZI Oncor, Gaithersburg, MD) is used at a final concentration of 5 pl/100 pi in hybridization buffer (50% formamide, 10% dextran sulfate, 0.004% Tween 20, and standard saline citrate (SSC) [in 1.5 strength]). A 10-pl volume of the probe is placed on an 18 x 18-mm coverslip, which is placed onto the slide, sealed with special Vulcanizing Fluid, and placed on a flat-bed thermal cycler. Slides are incubated for 3 min at 94°C and placed in a humidified box for 16 hr at 37°C. 

A special process for the production of coppered l,5-bis(2-hydroxyphenyl)-formazans 32 is based on the demethylative copperization of 1,5-bis(2-methoxy-phenyl)formazans [63], The method involves heating for a short time in pyridine, formamide, or dimethylformamide. 

Whereas a-amino ketones readily form imidazoles with formamide, they are often not easy to prepare. Accordingly, they can be replaced by precursors, a-oximino ketones, which can be reduced either by dithionite or using catalytic mehods in formamide at 70-100 °C. Ring closure can then be achieved by raising the temperature (Scheme 80). When a-ketol esters are used it appears that the imidazole formation may in this instance proceed by way of the oxazole. A further special case is the formation of 4,5-disubstituted imidazoles from 1-chloro-l,2-epoxides and formamide. One recent example of an application of Bredereck s method is the synthesis of the imidazolepropanol (144) from 3-bromo-2-methoxytetra-hydropyran (Scheme 81) (80AHC(27)241). 

A few of these reactions demand special comment. Dimethyl-formamide must act as a nucleophile in attacking an epoxide/ BF3 complex to give the ion (7), which suffers hydrolysis in water to give the 6j5-formate [152]. Boron trifiuoride and triethyl aluminium, both efficient Lewis acids, are able to promote reactions with substances which are only very weak proton acids e.g, alcohols and HCN). This may be due to... 

To probe for one-dimensional diffusion, we synthesized DNA/RNA chimeric oligonucleotides. Special precautions were taken to avoid ribonuclease contamination during synthesis, purification, and use of these chimeras. For example, all water was treated with diethylpyrocarbonate before exposure to the chimeras. Ribonucleotide 2 -hydroxyl groups were deprotected with 1 M tetrabutyl ammonium fluoride in dimethyl formamide (Aldrich Chemical Milwaukee, WI). Purified oligonucleotides were labeled on the 5 end with [y-32p]ATP (duPont Wilmington, DE) by T4 kinase (Promega Madison, WI), and desalted with a Nick gel filtration column (Pharmacia Uppsala, Sweden). 

Special prep 1 Benzene hlorofoim- saturated with formamide w... 

Special prep 1 Carbon tetrachloride saturated with formamide 81... 

A special class of enamino and enamidophosphonates is available from 1,2,2,2-tetrachloroethylformamide (obtained from chloral and formamide) and triethyl phosphite. The resulting formamidophosphonate may be hydrolysed to the corresponding aminophosphonate. Base treatment of the amido and aminophosphonate leads to enamido- or enamino-phosphonates, respectively. The former can be converted into oxazoles (or thiazoles ), which in turn can be converted into phosphonoglycine amides (equation 104). ... 

Properties of the three liquids of special interest are compared in Table I. The liquid surface tension, vlv > these reference liquids covers almost a threefold range at 20°C. In this same range are the surface tensions at 20°C. for the five other freshly purified liquids, formamide, hexachloropropylene, tert-butylnaphthalene, dicyclohexyl, and decane (58.2, 38.1,33.7, 32.8, and 23.9 dynes per cm., respectively). 

Disubstituted-2-methyl-1,2,3-triazinium iodides 114a-c are demethylated to the triazines 17m,s,u by reaction with formamide and diammonium persulfate (Equation 92) < 1991H(32)2015>. This special case has already been mentioned in Section 9.01.5.6 together with the removal of 2-dicyanomethylene groups from the 1,2,3-triazinium dicyanomethylides 34 (R = H R, R = Me, Et, Ph) under the same conditions see also <1996CHEC-11(6)483>. Cycloadditions of 2-ethyl-1,2,3-triazinium tetrafluoroborates and 1,2,3-triazinium 2-dicyanomethylides have been treated in Section 9.01.5.7. 

Capacity measurements in formamide, A -methylformamide (NMF) and dimethylformamide (DMF) were first described in 1961. The results differed from earlier non-aqueous solution measurements insofar as capacity humps were found in formamide and NMF (Fig. 7.2.2). Humps had previously been found only in aqueous solution and had been attributed to some special property of water. The amide hump occurs on the negative side of the potential of zero charge (pzc) in contrast to the water hump which is on the positive side. Recent measure-ments in a range of A -alkyl formamides, acetamides and propion-amides show that the cathodic hump occurs generally in amides having at least one unsubstituted iV-hydrogen atom. In fully substituted solvents like dimethylformamide and dimethylacetamide (DMA) the cathodic hump is absent but a different hump occurs on the anodic side of the pzc. In the A-alkyl acetamides and A-methylpropionamide both humps appear on the same capacity curve (Fig. 7.2.3). The two humps have been tentatively attributed to solvent dipole reorientation effects but the evidence for this is inconclusive. ... 

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