**2. Synthetic pathways of phosphonates and phosphonic acids**

Many synthetic pathways of phosphonates and phosphonic acids have been developed and presented in the literature. In this context, the most common and important of these pathways are discussed below:

#### **2.1 Michaelis:** *Arbuzov* **reaction**

This reaction is considered as the most used way to synthesize phosphonates derivatives. It consists of adding of a trialkylephosphite to an alkyl halide [5, 6]. **Figure 1** shows the path followed by this reaction.

**Figure 1.** *Michaelis-Arbuzov reaction.*

#### **2.2 Kabachnik-Fields reaction (phospha-Mannich)**

The Kabachnik-Fields reaction is one of the most important reactions for synthesizing α-aminophosphonates and α-aminophosphonic acids (**Figure 2**). In this

*Phosphonates and Phosphonic Acids: New Promising Corrosion Inhibitors DOI: http://dx.doi.org/10.5772/intechopen.109499*

**Figure 2.** *Kabachnik-Fields reaction.*

reaction, we react an amine, a carbonyl derivative and a dialkylephosphite together in one pot (one pot multi-component reaction) [7, 8].

#### **2.3** *Pudovik* **reaction**

In this reaction, dialkylephosphites are converted to α-hydroxyphosphonates in the presence of carbonyl derivatives in basic medium [9]. The sequence of this reaction is given in **Figure 3**.

**Figure 3.** *Pudovik reaction.*

#### **2.4** *Abramov* **reaction**

Concerning the Abramov reaction, the trialkylephosphite rich in electron can undergo a nucleophilic addition to the carbon atom of the carbonyl compound [10]. The **Figure 4** represents the sequence of this reaction.

**Figure 4.** *Abramov reaction.*

#### **2.5 Moedritzer-***Irani reaction*

This reaction is developed by Kurt Moedritzer and Riyad R. Irani [11]. It is a new simple and direct procedure to prepare α-aminophosphonic acids basing on the Kabachnik-Fields and Mannich reactions. Generally, the principle of this reaction consists to react the phosphors acid and formaldehyde with primary or secondary amines (**Figure 5**).

**Figure 5.** *Moedritzer-Irani reaction.*
