2-Naphthol

Recent development in the synthesis of heterocycles by 2-naphthol-based multicomponent reactions

2-Naphthol or β-naphthol is an important starting material that has drawn great attention in various organic transformations because of its attributes, such as low cost, easy to handle and eco-friendliness. The electron-rich aromatic framework of 2-naphthol with multiple reactive sites allows it to be utilized in several kinds of organic reactions eventuated to several organic molecules with potent biological properties. Multicomponent reaction approach has been tremendously utilized to explore the synthetic utility of 2-naphthol for the construction of diverse N/O-containing heterocyclic framework. In this review, we summarize recent data pertaining to multicomponent reactions, wherein heterocyclic compounds are synthesized utilizing 2-naphthol as one of the starting materials. It is anticipated that this review will stimulate the researchers to design new multicomponent strategies complying with the Green Chemistry principles for the further exploitation of 2-naphthol for the rapid synthesis of versatile biologically relevant heterocycles. This review provides a concise overview of the different 2-naphthol based multicomponent reactions utilized for the construction of diverse bioactive heterocyclic scaffold.

1-{Phen-yl[1-(p-tol-yl)ethyl-amino]meth-yl}-2-naphthol

The title compound, C(26)H(25)NO, was obtained via a one-pot synthesis from the reaction of 2-naphthol, 1-(p-tol-yl)ethyl-amine, p-toluene-sulfonic acid and benzaldehyde. There are three mol-ecules per asymmetric unit, all having similar conformations. There are intra-molecular O-H?N and C-H?O hydrogen bonds, with only van der Waals forces found between mol-ecules.

2-Naphthol Levels and Allergic Disorders in Children

Background: The measurement of polycyclic aromatic hydrocarbons (PAH) in ambient air is quite difficult to perform. Using urine biomarkers of PAH such as 2-naphthol is one approach to this problem. This study explored the association between urine 2-naphthol levels and allergic diseases. The associations between 2-naphthol levels and oxidative stress biomarkers for the possible disease pathogenesis were also investigated.
Method: A total of 453 kindergarten children from the (Childhood Environment and Allergic Diseases Study) CEAS cohort with urine samples were recruited. Urine 2-naphthol levels were measured by high-performance liquid chromatography mass spectrometry (HPLC-MS/MS) and markers of oxidative stress (8OHdG) were measured by enzyme-linked immunosorbent assays (ELISA). Information on environmental risk factors and allergic diseases were also collected. The association between 2-naphthol levels, 8OHdG levels, IgE, and allergic diseases were evaluated by multivariate linear regression and logistic regression.
Results: Levels of 2-naphthol were positively correlated with 8OHdG levels. A one ln-unit increase in the 2-naphthol level was positively associated to 8OHdG levels (per ln-unit: β = 100.61, p < 0.001). When dividing 2-naphthol levels into quartiles, asthma was significantly associated with 2-naphthol levels at a concentration of >1.60 ng/mL (adjusted OR: 3.14, 95% CI 1.34?7.35).
Conclusion: Urine 2-naphthol levels are associated with markers of oxidative stress and the risk of allergic diseases in young children.

Reflection of the Physiochemical Characteristics of 1-(2-pyridylazo)-2-naphthol on the Pre-concentration of Trace Heavy Metals

1-(2-pyridylazo)-2-naphthol (PAN) is a heterocyclic azo compound that forms inner, mostly reddish colored, water-insoluble chelates with many transition metal ions with metal ion-ligand ratios of 1:1 or 1:2. PAN is rather unselective but it does not form complexes with the alkali and alkaline earth metals, Ge(IV), As, Se and Te. Numerous reported techniques of pre-concentration have been considered for analyzing the role of PAN on the physiochemical outcome of the procedures. PAN been used as a chelating precipitant, flocculant, auxiliary complexing agent, as a ligand for anchoring on other supports with the purpose of introducing chelating property as well as selectivity. The role of PAN in the different techniques of pre-concentration, namely co-precipitation, membrane filtration, micro-extraction, cloud point extraction and solid phase extraction, has been investigated. PAN influences the optimum experimental parameters, namely pH, temperature, time, amount, tolerance limit, etc.

Theoretical study on thermal decomposition mechanism of 1-nitroso-2-naphthol

1-nitroso-2-naphthol has thermal instability of thermal decomposition, spontaneous combustion and even explosion. Its thermal decomposition characteristics were tested by synchronous thermal analyzer (TGA/DSC); The activation energy of the thermal decomposition process was calculated by Kissinger method; The infrared absorption characteristic spectra of the gas products produced in the thermal decomposition process were measured by TGA/DSC-FTIR, and the thermal decomposition reaction process was speculated. The results show that the initial temperature (T_onset) of TGA exothermic decomposition of 1-nitroso-2 naphthol is between 129.01 and 155.69 °C, and the faster the heating rate(β), the higher the T_onset, but the faster the thermal decomposition rate, the greater the heat release and the worse the thermal stability. The activation energy (E) of the thermal decomposition process is 83.323 kJ/mol calculated by Kissinger method. The dynamic test results of TGA/DSC-FTIR show that the main reaction of 1-nitroso-2 naphthol during heating is intermolecular dehydration to form ether, and the secondary reaction is decomposition into aliphatic nitro compounds, carbonyl compounds and amines. Sodium hydroxide will reduce the thermal stability of 1-nitroso-2 naphthol. After adding sodium hydroxide, the thermal decomposition process of 1-nitroso-2 naphthol has changed. The main reaction is that 1-nitroso-2-naphthol reacts with sodium hydroxide to produce sodium nitrophenol, which is further decomposed into aliphatic nitro compounds. The research results have guiding significance for finding the reasonable conditions and temperature of 1-nitroso-2 naphthol during storage and transportation.