Naphthaleneacetic acid (NAA) is a broad-spectrum plant growth regulator, which can promote cell division and expansion, induce the formation of adventitious roots, increase fruit setting, prevent fruit drop, and change the ratio of female and male flowers. It enters the plant and is transported to the whole plant along with the nutrient flow. Naphthalene acetic acid is suitable for cereal crops and fruit trees: when applied to cereal crops, it can increase tillering, spike rate and thousand-grain weight; when applied to fruit trees, it can promote flowering, prevent fruit drop, and achieve the effect of accelerating ripening and increasing production. The application of naphthaleneacetic acid in crops, fruit trees, vegetables and horticultural plants is relatively successful, and the research on its mechanism and effect is relatively comprehensive, and there are a large number of relevant literature reports.
Scope of application Naphthaleneacetic acid is used in cereal crops to increase tillering, spike rate and thousand-grain weight; naphthaleneacetic acid is used in cotton to reduce bud shedding, increase peach weight and improve quality. Naphthaleneacetic acid is used for fruit trees to promote flowering, prevent fruit drop, accelerate ripening and increase production. Naphthaleneacetic acid is used for fruits and vegetables to prevent falling flowers and form seedless fruits; naphthaleneacetic acid is used for cutting branches to promote rooting, etc.
Naphthaleneacetic acid degrades slowly under visible light, and the degradation rate of ultraviolet light with a dominant wavelength of 254nm is significantly greater than that of a dominant wavelength of 365nm. Anatase TiO2 powder has a good catalytic effect on the photodegradation of naphthaleneacetic acid. Under 254nm ultraviolet radiation, the photolysis half-life shortened from 60min to 39min. The photodegradation of naphthaleneacetic acid is easy to proceed in the presence of oxygen, and this reaction is a first-order kinetic reaction to NAA. Its photodegradation mainly manifests as oxidative decarboxylation, the -H on the aromatic ring is replaced by -OH, and then the naphthalene ring is broken and oxidized to phthalic acid and its derivatives.
There are many ways to synthesize 1-Naphthaleneacetic acid, the following are some common methods:
1. Diazo compound method: The steps of this method have been given in the previous question.
Step 1: Preparation of Barbituric acid from nitronaphthalene and acetone.
Step 2: react barbituric aldehyde with diazomethane to obtain 1-Naphthylmethylbarbituric acid.
Step 3: 1-naphthylmethylbarbiturine is reacted with sodium hydroxide to obtain 1-Naphthylacetic acid.
Step 4: Treat 1-naphthoic acid with ethyl iodide in methanol to obtain 1-naphthylacetic acid.
2. Phenolic method: prepare resorcinol with phenol and formaldehyde, and then react resorcinol with naphthaleneacetaldehyde to obtain 1-naphthaleneacetic acid.
Step 1: React phenol and formaldehyde under acidic conditions to obtain resorcinol (2-Hydroxyphenylphenol).
Step 2: Resorcinol and naphthalene acetaldehyde react under alkaline conditions to generate 1-naphthyl-2-(2-hydroxyphenyl)ethene (1-Naphthyl-2-(2-hydroxyphenyl)ethene).
Step 3: Reaction of 1-naphthyl-2-(2-hydroxyphenyl)ethylene with sodium hydroxide gives 1-naphthylacetic acid.
The chemical formula is as follows:
Step 1: Phenol + Formaldehyde → Resorcinol
Step 2: Resorcinol + naphthaleneacetaldehyde → 1-naphthyl-2-(2-hydroxyphenyl)ethene
Step 3: 1-naphthyl-2-(2-hydroxyphenyl)ethene + NaOH → 1-naphthylacetic acid
3. Aryl group substitution reaction method: The steps of this method have been given in the previous question.
The synthesis steps of the aromatic group substitution reaction method of 1-Naphthalene acetic acid are as follows:
Step 1: React benzoic acid and naphthalene in the presence of sulfuric acid to generate Naphthylbenzoic acid.
Step 2: React naphthylbenzoic acid with bromoacetic acid in the presence of sodium hydroxide to generate 1-naphthylacetic acid.
The chemical formula is as follows:
Step 1: Benzoic acid + Naphthalene + H2SO4 → Naphthylbenzoic acid
Step 2: Naphthylbenzoic acid + BrCH2COOH + NaOH → 1-naphthylacetic acid
4. Carbon dioxide catalytic method: use styrene and CO2 to react in the presence of a catalyst to obtain 1-naphthaleneacetic acid.
Step 1: React styrene and carbon dioxide under light to generate carboxylate.
Step 2: Hydrolyze the carboxylate under basic conditions to generate 1-naphthaleneacetic acid.
The chemical formula is as follows:
Step 1: Styrene + CO2 + Light → Carboxylate
Step 2: Carboxylate + NaOH → 1-Naphthylacetic acid
5. Photooxidation method: use naphthalene and ethylene acid to react under light to obtain 1-naphthylacetic acid.
Step 1: Expose naphthalene ethanol and air to ultraviolet rays for photooxidation to generate 1-naphthylacetic acid.
The chemical formula is as follows:
Naphthalene ethanol + O2 + light → 1-naphthylacetic acid
It should be noted that this method does not require special reaction conditions and reagents, and the operation is simple, but the reaction time is long and the product purity is low. In addition, this method is only applicable to compounds containing aromatic hydroxyl groups such as naphthalene ethanol, and is not applicable to other compounds. Different synthesis methods have different advantages and disadvantages, and the appropriate method should be selected for synthesis according to actual needs.