Substituents trimethylammonium

Syn elimination and the syn-anti dichotomy have also been found in open-chain systems, though to a lesser extent than in medium-ring compounds. For example, in the conversion of 3-hexyl-4-d-trimethylammonium ion to 3-hexene with potassium ec-butoxide, 67% of the reaction followed the syn-anti dichotomy. In general syn elimination in open-chain systems is only important in cases where certain types of steric effect are present. One such type is compounds in which substituents are found on both the P and the y carbons (the unprimed letter refers to the branch in which the elimination takes place). The factors that cause these results are not completely understood, but the following conformational effects have been proposed as a partial explanation. The two anti- and two syn-periplanar conformations are, for a quaternary ammonium salt ... 

Amino substituents in acyclic derivatives have been discussed by Eggert and Djerassi (396), who emphasize structural and conformational effects, whereas Batchelor has investigated SCS(NH2) and nitrogen protonation shifts in methylated cyclohexylamines (424). The, 3C NMR spectra of amino acids have been compared with those of amines and carboxylic acids (425,426). The transmission mechanisms of amino, ammonium, trimethylammonium, acetamido, and di-acetamido groups have been examined by Faure and co-workers (427), the SCSs of nitro groups by Ejchart (400), and those of azido functions in steroids by Lukacs and co-workers (428). 

Of the derivatives of (2-chloroethyl)trimethylammonium chloride which have been synthesized and tested as plant growth substances for the reduction of the height of plants, numerous substituents at the X site produced derivatives with biological effect (15). The most active derivatives were the chloride or bromide salts of CH0CI-CH0-N+ (CH3)3, CH>Br-CH -N+ (CH3) 3, CHo=CH-CH2-... 

The salicylaldehydes commonly used have nitro, alkoxy, or halogen substituents, and need no further comment. Some unusual ones have cationic substituents 3-, 4- and 5-methylthio- and dimethylaminosalicylaldehydes have been prepared and methylated to the corresponding dimethylsulfonium and trimethylammonium salicylaldehydes. 1012 The salicylaldehyde substituted in the 4-position with a 3,5-diphenyl-2-pyrazolin-l-yl group gives a series of BIPS and spiro(dipyrans) having highly fluorescent spiro forms and nonfluorescent open forms, which is the reverse of the usual situation. 13... 

The spectral changes associated with the protonatiop of p -dimethylamino-derivatives [45] contrast sharply with those described above. There is a hypsochromic shift of the maximum absorption and the absorption spectrum of the conjugate acid of benzylidene-p -dimethylaminoaniline is closely similar to that of benzylideneaniline free base, which leads to the conclusion that the monocation has the ammonium structure. The conjugate acid of benzylidene-p -dimethylaminoaniline shows, however, an additional peak at 455 nm, which was ascribed to the anilium form, but the position of the tautomeric equilibrium could not be determined without the knowledge of the extinction coefficients of the two forms, p/fj-values of only a few of these compounds were estimated from these measurements on flowing solutions. So, for example, p-trimethylammonium-benzylidene-p-toluidine has a p/La-value of 1 85, and for variable p -substituents a p-constant of T5 has been calculated. The p -dimethylamino group may be expected to have p/fa in excess of 5. 

A trichloromethyl substituent has been used as a leaving group for amine nucleophiles. Triazine 281 was converted to aminotriazines 282 and 283 (84KGS1674 85KGS1557). The trimethylammonium group of 284 has been substituted by alkoxides to give triazines 285 (85KGS1125). 

SAMPLE SOLUTION (a) Think of the two compounds as substituted derivatives of acetic acid. A fert-butyl group is slightly electron-releasing and has only a modest effect on acidity. The compound (CH3)3CCH2C02H is expected to have an acid strength similar to that of acetic acid. A trimethylammonium substituent, on the... 

No substantial barrier to rotation of a 6jS-trimethylammonium substituent could be demonstrated by low-temperature n.m.r. studies. It is suggested that strains involved in the interactions between the rotating 6j9-substituent and the 10)3-methyl group are relieved by bond bending. 

Steric and conformational effects also play a significant role in determining the symanti ratio. With Al-(6,6-disubstituted-ethyl)-Al,Al,Al-trimethylammonium ions, syn elimination is more prevalent when the 6-substituents are aryl or branched. As the 6-groups become less bulky, the amount of syn elimination decreases. This effect is illustrated by the data below. ... 

Many synthetic porphyrins have been prepared which are substituted at the meso positions (5,10,15,20). Porphyrins that have only alkyl or aryl substituents are insoluble in water. Water soluble porphyrins are made by introducing charged groups, such as carboxylate, sulfonate, trimethylammonium, or pyridinium. Some common synthetic porphyrins and their abbreviated notations are shown below. 

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