5-amino-8-hydroxyquinoline

Condensation of 2-amino-4-phenyithiazole with 8-hydroxyquinoline (73) through the intermediacy of the formaldehyde Mannich base illus-... 

Corrosion Inhibitors. Steel-reinforcing wire and rods embedded in concrete containing quinoline or quinoline chromate are less susceptible to corrosion (72) (see Corrosion and corrosion control). Treating the surface of metals with 8-hydroxyquinoline [148-24-3] makes them resistant to tarnishing and corrosion (73). Ethylene glycol-type antifreeze may contain quinoline, 2-chloro-, 4-amino-, 8-nitro-, or 8-hydroxyquinoline to prevent corrosion (74). 

In acidic solution, the degradation results in the formation of furfural, furfuryl alcohol, 2-furoic acid, 3-hydroxyfurfural, furoin, 2-methyl-3,8-dihydroxychroman, ethylglyoxal, and several condensation products (36). Many metals, especially copper, cataly2e the oxidation of L-ascorbic acid. Oxalic acid and copper form a chelate complex which prevents the ascorbic acid-copper-complex formation and therefore oxalic acid inhibits effectively the oxidation of L-ascorbic acid. L-Ascorbic acid can also be stabilized with metaphosphoric acid, amino acids, 8-hydroxyquinoline, glycols, sugars, and trichloracetic acid (38). Another catalytic reaction which accounts for loss of L-ascorbic acid occurs with enzymes, eg, L-ascorbic acid oxidase, a copper protein-containing enzyme. 

The Pomeranz-Fritsch-Bobbitt cyclisation of activated amino-acetal 38 yielded the desired 4-hydroxyquinoline 39 in acceptable yield. The non-obvious regioselectivity of the cyclisation can be attributed to the overriding para-directing effect of alkoxy groups. ... 

Aziridine esters are a- and -amino acid derivatives at the same time. A characteristic reaction of a-amino acids is their reaction with triethylboron to give boroxazolidines. We showed that aziridinecarboxylic acids exhibit the expected behavior in their reaction with triethylboron, viz., that they form stable boroxazolidines 34 (Scheme 19) [29]. These boron heterocycles can be reconverted into the free amino acids by treatment with 8-hydroxyquinoline. 

GFP hopo ICBP IP3 Ln3+ mal memal MLCK nota oxine par pdta pmea py quin-2 green fluorescent protein hydroxypyridinon(at)e intestinal calcium-binding protein inositol 1,4,5-triphosphate a lanthanide(III) cation malonate methylmalonate myosin light chain kinase 1,4,7-triazacyclononane-l,4,7-triacetate 8- hydroxyquinoline pyridine-2-azo-4 -dimethylaniline propylene-1,2-diaminetetraacetate 9- [2-(phosphonomethoxy)ethyl] adenine pjrridine pjrridyl 8-amino-2- [(2-amino-5-methylphenoxy )methyl] -6-methoxyquinoline-ATJV -tetraacetate 2- [ [2-[his(carboxymethyl)amino]-5-methyl-phenoxy] methyl] -6-methoxy-8- [bis(carboxymethyl) amino] quinoline]... 

Pyrimido[l,2-a]quinoline-2-carboxylate (1055, R = Et, R2-R4 = H) was obtained in 50% yield when 2-aminoquinoline was reacted with EMME in boiling Dowtherm A for 20 min (74MIP1). The 6-hydroxy derivative of 1055 (R = Et, R2 = OH, R2 = R4 = H) was prepared in 20% yield when 2-amino-4-hydroxyquinoline and EMME were heated at 170°C for 8 hr (71IJC201). The angular pyrimido[l,2-a]quinoline-2-carboxylate (1055, R = Et, R2-R4 = H) could not be transformed into the linear isomer [77JCS(P1)780],... 

Wentrup and co-workers also studied the flash vacuum pyrolysis of isopropylidene (monosubstituted amino)methylenemalonates (84JOC-2772). The pyrolysis of isopropylidene phenylaminomethylenemalonates (1223) between 400 and 600°C under a pressure of 10 5-10 3 torr afforded 4-hydroxyquinolines (1226) in 57-66% yields. The intermediates (1224 and 1225) of the pyrolysis of isopropylidene phenylaminomethylenemalonates (1223) could be isolated at - 196°C on KBr or BaF2 windows in a special apparatus allowing direct IR spectroscopic examination of the pyrolysates... 

An extractive spectrophotometric procedure based on the complexation of reduced Iron(II) with 5-Chloro-7-iodo-8-hydroxyquinoline (CIHQ) for the estimation of micro amounts of vitamin C. The resulting brown colored complex was extracted into chloroform to give a reddish brown extract which shows an absorption band at 485 nm. This chelate was formed immediately and the apparent molar absorptivity and Sandell s sensitivity for vitamin C was found to be 8.5 x 105 dm3 mol"1 cm 1 and 2.072xl0 4g cm 2. Linear relationship between absorbance and concentration of ascorbic acid is observed up to 0.8 pg ml"1. Interference studies of different substances including sugars, vitamins and amino acids, metal ions and organic acids were carried out. The utility of the method was tested by analysing some of the marketed products of vitamin C... 

The reaction of N,N- dimethylaniline with pyridine (equation 55) should also be considered in this category. Enamines usually attack acylated N- oxides at position 2 unless it is blocked, as in 2-methylquinoline 1-oxide, when attack takes place at C-4. Methyl /3-aminocrotonate attacks quinoline and isoquinoline AT-oxides at the position a to the N- oxide function in the presence of tosyl chloride (78JHC1425). However, pyridine and 2-methylpyridine 1-oxides react at the 4-position (equation 142). A low yield of by-product (242) is formed in each case, probably as a result of self-condensation of methyl /3-aminocrotonate. 4-Hydroxyquinoline 1-oxide is exceptional in that it reacts with an enamine in the presence of tosyl chloride at the /3-position (Scheme 170) (B-71MI20500). 5-Amino-3-methylisoxazole reacts with quinoline 1-oxide at the a-position, and the product can be degraded, to afford ultimately 2-methylquinoline (Scheme 171) (78CPB2759). 

Amino-8-hydroxyquinoline hydrochloride [3881-33-2] M 196.7. Dissolved in minimum of MeOH, then Et2O was added to initiate pptn. Ppte was filtered off and dried [Lovell et al. JPC 88 1885 1984]. 

As carboxylic esters of 8-hydroxyquinoline are readily hydrolyzed in the presence of metal ions, it has been possible to develop the carbo(8-quinoloxy) substituent as an amino-protecting group for peptide synthesis (Scheme 14). 

This deactivation of the amino group in (J-hydroxyalkylamines has already been proposed by Alvey 70) and is supported by the results of the initiation of copolymerization by quinoline and its 8-hydroxy derivative. Whereas a high initiation efficiency was found for quinoline, 8-hydroxyquinoline, a very effective chelating agent, does not initiate copolymerization 69). 

In the photometric determination of copper, a coupling product formed between the diazonium salt from 2-amino-pyridine and resorcinol, or 4-(2-pyridinylazo)-l,3-benzenediol 21, has been used. Here the formed copper complex under acetate buffer exhibits an absorption peak at 520 nm, which is measured photometrically <2003KPU28>. Similarly for photometric determination of iron(ll), a coupling product formed between the diazonium salt of 2-amino-4,6-dihydroxypyrimidine and 8-hydroxyquinoline, or 6-hydroxy-2-(8-hydroxy-7-quinolinyl)azo-4(l//)-pyrimidinone 22, has been used. This reagent forms a blue complex with iron(n) ions with an absorption maximum at 625 nm that does not interfere with the presence of other metals <2003KD95>. 

In this connection, the limitations of the pyrrole ring annulation onto 2-amino-3-bromotropones were investigated (63MI2). With 549, the frontier between the normal cyclization (to type 550) and the rearrangement (to give 8-hydroxyquinoline 551) lies between the uses of cyanoacetate and... 

Although several peroxidase enzymes obtained from plant, animal, and microbial sources have been investigated for their ability to catalyze the removal of aromatic compounds from wastewaters, the majority of studies have focused on using HRP. In particular, it has been shown HRP can transform phenol, chlorophenols, methoxyphenols, methylphenols, amino-phenols, resorcinols, and various binuclear phenols [7], HRP was also used for the treatment of contaminants including anilines, hydroxyquinoline, and arylamine carcinogens such as benzidines and naphthylamines [7,8]. In addition, it has been shown that HRP has the ability to induce the formation of mixed polymers resulting in the removal of some compounds that are either poorly acted upon or not directly acted upon by peroxidase [7], This phenomenon, termed coprecipitation or copolymerization, has important practical implications for wastewaters that usually contain many different pollutants. This principle was demonstrated when it was observed that polychlorinated biphenyls (PCBs) could be removed from solution through coprecipitation with phenols [20]. However, this particular application of HRP does not appear to have been pursued in any subsequent research. 

The intra-complex PCMU are those compounds in which at least one fragment is linked with the metal ion via both a valent and coordination bond. It should be noted that such compounds can be neutral, cationic, anionic or contain, in addition to chelating ligands, monofunctional varieties. The number of such PCMU is enormous therefore we shall indicate the most frequent types. A detailed consideration has been given earlier to complexes of metals with polymers containing diketone [13], o-hydroxyazomethine [14], enaminoketone [15], amino add [16], 8-hydroxyquinoline [17] and other groups. 

Oxidative amination, using a Cun-catalyst was reported to take place on treatment of 6-hydroxyquinoline with secondary amines in a methanol solution, 8-R2N-quinoline-5,6-dione being obtained. So besides a SNH (amino) reaction at C-8, a SNH(oxo) reaction occurs at C-5 (Scheme 11) (90CPB2841). A similar reaction was found earlier with 5-hydroxybenz-imidazoles (Scheme 11) (78KGS1680)... 

The excited state pA-behaviour of quinoline derivatives has received considerable attention (see Tables 6.3 and 6.4). Since the heterocyclic nitrogen atom of quinoline is expected to become a stronger base in the excited state while the acidity of hydroxyl or amino-substituents increases, different ionization sequences can be obtained in the S0 and states. 3-Hydroxyquinoline is a typical example of this behaviour as shown in Scheme 2 (Haylock et al., 1963 Mason et al., 1968). 

The oxazolo[4,5-/z]quinolin-2(3//)-ones (89) and 2,5-disubstituted oxazolo[4,5-/i]quinolines (90) were prepared as new antiallergic agents by oxazole ring annelation conducted by condensing 7-amino-8-hydroxyquinoline intermediates with phosgene, o-ester, or imidate reagents (Scheme 7)... 

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