Methoxy , determination

The results of methoxy determinations after the reaction with diazomethane are presented in Table IV. The same carbon samples were used as in Table I. When dry ether was taken as solvent, acidic groups... 

Comparison of Netdralizalion Values and Methoxy Determinations after Methylation with Diazomethane [after Diehl (47)Y... 

In these examples the base name of the benzene derivative determines the carbon at which numbering begins anisole has its methoxy group at C 1 toluene its methyl group... 

This reaction has been used m an imaginative way to determine the ring size of glycosides Once all the free hydroxyl groups of a glycoside have been methylated the glycoside is subjected to acid catalyzed hydrolysis Only the anomeric methoxy group IS hydrolyzed under these conditions—another example of the ease of carbocation for matron at the anomeric position... 

Unsaturation value can be determined by the reaction of the akyl or propenyl end group with mercuric acetate ia a methanolic solution to give acetoxymercuric methoxy compounds and acetic acid (ASTM D4671-87). The amount of acetic acid released ia this equimolar reaction is determined by titration with standard alcohoHc potassium hydroxide. Sodium bromide is normally added to convert the iasoluble mercuric oxide (a titration iaterference) to mercuric bromide. The value is usually expressed as meg KOH/g polyol which can be converted to OH No. units usiag multiplication by 56.1 or to percentage of vinyl usiag multiplication by 2.7. 

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

Aromatic methoxy group determination Anisole 1 is heated in HI (10 mL) arxi the methyl iodide which distills is trapped In AgNOs. The Agl is determined gravimetncally. 

The anomeric effect is also present in acyclic systems and stabilizes conformations that allow antiperiplanar (ap) alignment of the C—X bond with a lone-pair orbital of the heteroatom. Anomeric effects are prominent in determining the conformation of acetals and a-alkoxyamines, as well as a-haloethers. MO calculations (4-3IG) have found 4kcal/mol as the difference between the two conformations shown below for methoxy-methyl chloride. ... 

The occurrence of nucleophilic participation is also indicated by a rate enhancement relative to the rate of solvolysis of n-butyl p-bromobenzenesulfonate. The solvolysis rates of a series of cu-mefhoxyall l p-bromobenzenesulfontes have been determined. A maximum rate is again observed where participation of a methoxy group via a live-membered ring is possible (see Table 5.20). 

X-r crystal structure determinations have been completed on two salts containing bicyclo[2.2.1]heptyl cations (Fig. 5.12). Both are more stable than the 2-norbomyl cation itself 18 is tertiary whereas 19 contains a stabilizing methoxy group. The crystal structure of 18 shows an extremely long (1.74 A) C—C bond between C-1 and C-6. The C(1)—C(2) bond is shortened to 1.44 A. The distance between C-2 and C-6 is shortened from 2.5 A in norbomane to 2.09 AThese structural changes can be depicted as a partially bridged structure. 

In a similar attempt, Decker and Eichler reduced A -methylnor-papaverinium phenolbetaine (VIII) with tin and hydrochloric acid and obtained i/i-laudanine, m.p. 112°, pierate, m.p. 162-3°, which was subsequently investigated by Spath and Epstein, who showed that on methylation it furnished dMaudanosine and that the ethyl ether on energetic oxidation yielded veratric acid (3 4-dimethoxybenzoic acid) and the methyl ethyl ether of nor-m-hemipinic acid. This clearly indicated that the free hydroxyl group was in the woquinoline nucleus, and its position was determined by the fact that on mild oxidation 7-methoxy-6-ethoxy-l-keto-2-methyl-l 2 3 4-tetrahydrowoquinoline, m.p. 95-6°, was produced, and on this basis these authors assigned formula (IX R = H R = CH3) to -laudanine. 

Methoxy-cis-19-norpregna-l,3,5(10),17(20)-tetraene A solution of 31 g (109 mmolesi of estrone methyl ether in 600 ml of benzene is added rapidly to a solution of 469 mmoles of ethylidenetriphenylphosphorane in 1.2 liters of DMSO. After heating under nitrogen at 60° overnight, the reaction is cooled, poured into ice water, and extracted with three portions of hexane, backwashed with three portions of water and the hexane removed. The crude product, dissolved in petroleum ether (bp, 30-60°), is filtered through 225 g of alumina (activity I). The residue from the eluate consists of 95 % cis- and 5 % tran5-isomers, as determined by vpc analysis. After recrystallization from ether-methanol, 26.3 g (82%) of cw-isomer is obtained mp 76.5-77.5° [a]o 60°. 

In their acidity, basicity, and the directive influence exerted on electrophilic substitution reactions in benzenoid nuclei, acylamino groups show properties which are intermediate between those of free amino and hydroxyl groups, and, therefore, it is at first surprising to find that the tautomeric behavior of acylaminopyridines closely resembles that of the aminopyridines instead of being intermediate between that of the amino- and hydroxy-pyridines. The basicities of the acylaminopyridines are, indeed, closer to those of the methoxy-pyridines than to those of the aminopyridines, the position of the tautomeric equilibrium being determined by the fact that the acyl-iminopyridones are strong bases like the iminopyridones and unlike the pyridones themselves. Thus, relative to the conversion of an... 

X-Ray crystal structure determinations of l-(aminocarbonyl)-3-methyl-4-methoxy-l//-pyrazol-5(2H)-one 107 (R = H) and l-(phenylaminocar-bonyl)-3-methyl-4-methoxy-l//-pyrazol-5(2H)-one 107 (R = Ph) demonstrated that both molecules exist in the crystal exclusively as NH-CO tautomers (97T5617). The tautomeric form similar to 104b is realized in the crystal of 4,4-dichloro-substituted pyrazolone 108 (93BSB735). 

The values of the 1-hydroxy moiety of (5)-(- -)-iVb-acetyl- 1-hydroxytrypto-phan methyl ester (32), methyl l-hydroxyindole-3-butylate (33), iVb-methoxy-carbonyl-l-hydroxytryptamine (34), 1-hydroxymelatonm (19), l-hydroxy-6-nitroindole (35), and l-hydroxy-5-nitroindole (36) are determined to be 9.8, 8.4, 8.2, 8.1, 6.9, and 6.8, respectively (Fig. 2) (2000H1881). Thus, 1-hydroxyindoles are weak acids, stronger than phenol and weaker than succinimide. Therefore,... 

Eupe and Majewski attempted to determine by experiment the influence of the relative positions of osmophores on each other in the same molecule. In the case of the three methyl tri-azo-benzoates no great difference in the type of odour exists, only a difference in the strengths, the para compound being the strongest and the ortho the weakest. Of the three methoxy-acetophenones, as another example, the meta isomer is almost odourless in comparison with the ortho and para. 

D) 4 -[N-Ethyi-1 "-Methyl-2 -(4" -Methoxyphenyl)Ethylamino]Butyi-3,4-Dimethoxybenzoate Hydrochloride 10.3 g of 4 -iodobutyl-3,4-dimethoxybenzoate and 11.0 g of N-ethyl-p-methoxyphenylisopropylamine (obtained by catalytic reduction of an alcoholic solution of an excess quantity (60%) of p-methoxy-phenyl-acetone, to which was added a 33% (weight-for-weight) aqueous solution of ethylamine, with Pt as a catalyst), were boiled in 200 ml of methyl ethyl ketone for 20 hours, cooled and the iodine ion was determined the reaction was found to be complete. Then the methyl ethyl ketone was evaporated in vacuo and the residue was dissolved in 300 ml of water and 30 ml of ether the layers were separated and the water layer was extracted twice more with 20 ml portions of ether. 

An X-ray crystal structure of 7-methoxy-5//-dibenz[c,c]azepine reveals that the seven-mem-bered ring is in the boat conformation.7 Likewise, X-ray structural determinations of 2-morpho-lino-5H-d benz.[A/]azepi ne,7 and 5//-dibenz[/>, /]azepi ne.1 " 11 and its 5-acyl derivatives,12 in-... 

Detailed IR and UV spectroscopic data on 5//-dibenzfc,c]azepine5 and its 7-methoxy- and 7-methylsulfanyl derivatives7 have been reported. IR, UV and HNMR spectroscopic data for 2-amino-3//-l-benzazepin-3-one, 2-amino-l//-3-benzazepin-l-one, and 6-amino-7H-dibenz[7>,(/]azepin-7-one have been gathered,27 and confirm their oxo amidinc structures. Spec-trophotometrically determined pATa values of 4.46 and 5.20 (in water at 21 C) have been obtained for 1 l//-dibenz[(>,e]azepine and its 6-methyl derivative, respectively.28... 

E The optical purity was determined after conversion to methyl (+ )-(5 )-2-methoxy-2-phenylpropanoatc. 

A solution of potassium naphthalenide is prepared from 2.0 g (50 mmol) of potassium and 6.4 g (50 mmol) of naphthalene in 40 mL ofTHF. After 1 h at r.t. this mixture is diluted with 10 mL of diethyl ether and 10 mL of petroleum ether (bp 40-60 °C) and cooled to — 120 °C. 4.5 g (25 mmol) of ( )-l-methoxy-3-phenylthio-1-propcne arc added followed by 3.36 g (25 mmol) of chlorobis(l-dimethylamino)borane. This mixture is allowed to warm to r.t. over 3 h the solvents are removed in vacuo and the residue is carefully distilled through a 5-cm column at 10 2 Torr. The distillate, containing also naphthalene, is dissolved in 30 mL of diethyl ether and treated with 2.95 g (25 mmol) of pinacol for 3 h. The crude product is chromatographed over 30 g of basic alumina (activity 1) using petroleum ether (bp 40 -60°C) giving 9.2 g of a mixture of product and naphthalene the yield of product (89% E) is determined to be 60% by H-NMR analysis. Similarly prepared is ... 

The enantiomeric excesses of the cyanohydrins obtained are determined via the diastereomcric Mosher esters with (/ )-a-methoxy-a-(trifluoromethyl)phenylacetyl chloride16 by GC. 

The exact time and temperature required for complete reaction must be determined for each individual compound. It has been observed that nucleophilic demethylation of methyl o-alkoxyaryl ethers is accelerated relative to anisole [Benzene, methoxy-],6 and this reaction is no exception. Lithium diphenylphosphide cleavage of anisole is complete in about 4 hours in refluxing tetrahydrofuran, whereas the present reaction is complete within 2 hours at 25°. 

The effects of some methoxy substituents were determined for the reaction with diphenylmethanol at a range of sulphuric acid concentrations in acetic acid containing 0.55 M water at 25 °C (Table 92)366. The logarithms of the rate coeffi-... 

Similar reasoning was applied to determination of the reacting form of 1-hy-droxy-2,6-dimethyl-4-pyridone, its rate being compared to that of 4-methoxy-... 

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