Ethyl groups determination

At first glance splitting may seem to complicate the interpretation of NMR spectra In fact It makes structure determination easier because it provides additional information It tells us how many protons are vicinal to a proton responsible for a particular signal With practice we learn to pick out characteristic patterns of peaks associating them with particular structural types One of the most common of these patterns is that of the ethyl group represented m the NMR spectrum of ethyl bromide m Figure 13 15... 

Acid catalyzed cleavage of aromatic methyl or ethyl ethers Quantitative methoxy group determination Also ether cleavage with tnmethylsilyl Iodide ... 

In opocinchenine the hydroxyl group must, therefore, be in the ortho-position relative to the point of attachment of the benzene ring to the quinoline nucleus. The relative positions of the two ethyl groups are determined by the fact that apocincheninic acid ethyl ether on oxidation with lead peroxide and sulphuric acid gives the lactone of hydroxyopo-cincheninic acid ethyl ether (I), which, on oxidation by sodium hypo-bromite, yields quinolylphenetoledicarboxylic acid (II). 

Cordes et al995 carried out alkaline hydrolyses of p-nitrophenylhexanoate 55 (PNPH) in the presence of poly-4-vinylpyridine partially quaternized with dodecyl-bromide and ethylbromide (QPVP). They also found that the polyelectrolytes are increasingly effective as catalysts with an increasing ratio of dodecyl to ethyl groups, and the hydrophobic interactions are important in determining the catalytic efficiency. They observed the inhibitory effects of several gegen-anions fluoride ions are the weakest inhibitor, and nitrate is the strongest (F- < Cl < S04 [Pg.159]

The author also included, for a reason that will be given later, the three alcohols used in the author s laboratory by the students. We excluded ethyl malonate, which caused problems. We will not go into detail concerning calcuiations of S and group determination since these aspect were largeiy covered previously. We will not pass any judgement on the different approaches, ietting the reader be his own judge. 

The complexity of the metabolism of alachlor, acetochlor, butachlor, and propachlor has led to the development of degradation methods capable of hydrolyzing the crop and animal product residues to readily quantitated degradation products. Alachlor and acetochlor metabolites can be hydrolyzed to two major classes of hydrolysis products, one which contains aniline with unsubstituted alkyl groups at the 2- and 6-positions, and the other which contains aniline with hydroxylation in the ring-attached ethyl group. For alachlor and acetochlor, the nonhydroxylated metabolites are hydrolyzed in base to 2,6-diethylaniline (DBA) and 2-ethyl-6-methylaniline (EMA), respectively, and hy-droxylated metabolites are hydrolyzed in base to 2-ethyl-6-(l-hydroxyethyl)aniline (HEEA) and 2-(l-hydroxyethyl)-6-methylaniline (HEMA), respectively. Butachlor is metabolized primarily to nonhydroxylated metabolites, which are hydrolyzed to DEA. Propachlor metabolites are hydrolyzed mainly to A-isopropylaniline (NIPA). The base hydrolysis products for each parent herbicide are shown in Eigure 1. Limited interference studies have been conducted with other herbicides such as metolachlor to confirm that its residues are not hydrolyzed to the EMA under the conditions used to determine acetochlor residues. Nonhydroxylated metabolites of alachlor and butachlor are both hydrolyzed to the same aniline, DEA, but these herbicides are not used on the same crops. 

The ODPM reactivity of aldehydes 65 is surprising because, as mentioned earlier, the only two ODPM reactive acyclic p, Y-unsaturated mono-C-2-substi-mted ketones are compounds 3 and 64a. Each of these substrates contains bulky substiments at C-2. However, the observations made with 65c and 65d, each having ethyl groups at C-2, clearly demonstrates that the bulk of the C-2 substituent is not an important feature in determining the ODPM reactivity of p, Y-unsam-rated aldehydes. However, it should be noted that the isopropyl substituted aldehydes, 65a and 65b, do react more efficiently, in qualitative terms, than 65c and 65d. 

Elemental composition Pb 64.06%, C 29.70%, H 6.23%. Tetraethyl lead is dissolved in benzene or toluene, diluted appropriately, and analyzed by GC/MS. The ethyl group may be determined by NMR spectroscopy. 

The structures in the solid state of three of the initially formed organomagnesium amides, 222, 223 and 224, were determined by X-ray crystallography. All three compounds are discrete monomers and have comparable structures of which that of 222 is shown (Figure 93). In 222 the ethyl group is a-bonded to magnesium and interacts with the three nitrogen atoms of the A-alkylated 2,6-bis(imino)pyridine in a pincer-type ... 

The X-ray crystal-structure determination of ethylmagnesium tris(3-phenylpyrazolyl) hydroborate (232) (Figure 94) shows that the magnesium atom is penta-coordinate as the result of one a-bonded ethyl group, three magnesium-nitrogen bonds with the tris(3-phenylpyrazolyl)hydroborate moiety and one additional, coordinating THF molecule. 

Direct determination of C-labeled ethyl groups bound on the surface of titanium trichloride samples, treated either with triethylaluminum or di-ethylaluminum monochloride solutions, at different temperatures. 

The number of ethyl groups, and, therefore, the number of the corresponding active centers found in the catalytic system diethylaluminum monochloride-a-titanium trichloride, is smaller than the one found in the system triethylaluminum-a-titanium trichloride. It is interesting to notice that for the two samples of a-TiCh (A and B), the activity ratio in the propylene polymerization is almost equal to the ratio (determined from ethyl groups) between the number of active centers (Table XI) (38). 

The method employed to calculate the total number of active centers relies upon the determination of the variation occurring in the ratio between ethyl groups (deriving from the alkylaluminum) which are present in the polymer and the whole amount of polymerized propylene, on increasing the time of polymerization. 

The data obtained through adsorption measurements may be defective because, by this method, only the ethyl groups, which are present on the surface of a-titanium trichloride since the start of the polymerization, have been determined. 

An X-ray crystal strnctnre determination of the product obtained from the reaction of methyl A-phenylcarbamate with Et2Zn (equation 24) shows the formation of a complex aggregate containing two zinc-bonded ethyl groups, four zinc atoms and six deprotonated carbamate molecules, instead of the anticipated ethylzinc carbamate . ... 

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