Question

Name the following compounds: (a) \(\mathrm{CH}_{3} \mathrm{PHCH}_{2} \mathrm{CH}_{3}\) b. c. (d) \(\mathrm{P}\left(\mathrm{OC}_{2} \mathrm{H}_{5}\right)_{3}\) (e) \(\mathrm{O}=\mathrm{P}\left(\mathrm{OC}_{2} \mathrm{H}_{5}\right)_{3}\) f. (g) \(\left(\mathrm{C}_{6} \mathrm{H}_{5}\right)_{2} \mathrm{P}-\mathrm{N}\left(\mathrm{C}_{2} \mathrm{H}_{5}\right)_{2}\) (h) \(\mathrm{CH}_{3} \mathrm{PHCl}\) i. j .k l.

Short answer

(a) N-methyl-N-ethylphosphine (d) Triethyl phosphate (e) Triethyl phosphite (g) N,N-diethyl diphenylphosphinoamine (h) Methylphosphine chloride

Step-by-step solution

(a) Naming the compound \(\mathrm{CH}_{3} \mathrm{PHCH}_{2} \mathrm{CH}_{3}\)

The given compound contains carbon and hydrogen atoms connected to a phosphorus atom. It is an organophosphine with the general formula \(\mathrm{R}_{3} \mathrm{P}\). In this case, the compound is \(\mathrm{CH}_{3} \mathrm{PHCH}_{2} \mathrm{CH}_{3}\). The compound can be named as N-methyl-N-ethylphosphine.

(d) Naming the compound \(\mathrm{P}\left(\mathrm{OC}_{2} \mathrm{H}_{5}\right)_{3}\)

This compound contains a phosphorus atom bonded to three ethoxy groups. The ethoxy group is an alkoxy group with the general formula \(\mathrm{R}-\mathrm{O}\). In this case, we have a trialkyl phosphate with the ethoxy group as the alkyl substituents. The compound can be named as triethyl phosphate.

(e) Naming the compound \(\mathrm{O}=\mathrm{P}\left(\mathrm{OC}_{2} \mathrm{H}_{5}\right)_{3}\)

In this compound, we have a phosphorus atom double bonded to an oxygen atom, and also bonded to three ethoxy groups. The general formula for this type of compound is \(\mathrm{O=PR(OR')_{3}}\). The compound can be named as triethyl phosphite.

(g) Naming the compound \(\left(\mathrm{C}_{6} \mathrm{H}_{5}\right)_{2}\mathrm{P}-\mathrm{N}\left(\mathrm{C}_{2} \mathrm{H}_{5}\right)_{2}\)

This compound has a phosphorus atom bonded to two phenyl groups (benzene rings) and an amine functional group with two ethyl substituents on nitrogen. The compound can be named as N,N-diethyl diphenylphosphinoamine.

(h) Naming the compound \(\mathrm{CH}_{3} \mathrm{PHCl}\)

This compound contains a phosphorus atom bonded to a chlorine atom, a methyl group, and a hydrogen atom. This is similar to the compound in part (a), but with a chlorine atom instead of an ethyl group. The compound can be named as methylphosphine chloride.

Key concepts

Organophosphine

Organophosphines are a class of organophosphorus compounds characterized by the presence of a phosphorus atom bonded to carbon atoms in the form of alkyl or aryl groups. They often follow the general formula \( R_3P \), where \( R \) can represent a variety of different organic substituents.

Typically, organophosphines serve as ligands in coordination chemistry, where they bond to metal atoms in various compounds. In organophosphines, phosphorus is in the trivalent state, meaning it has three bonds with carbon. When naming an organophosphine, the organic groups attached to the phosphorus atom are listed in alphabetical order, followed by the word 'phosphine'. For example, the compound \( CH_3PHCH_2CH_3 \) is named as N-methyl-N-ethylphosphine, noting the specific substituents attached to phosphorus.

Triethyl Phosphate

Triethyl phosphate is an organophosphorus compound with the formula \( P(OCH_2CH_3)_3 \). It's comprised of a phosphorus atom bonded to three ethoxy (\( -OCH_2CH_3 \) groups.

As a simple ester of phosphoric acid, triethyl phosphate is used in various applications such as a plasticizer, a flame retardant, and sometimes as a mild solvent or reagent in organic synthesis. The 'triethyl' prefix indicates the presence of three ethyl groups bonded to the oxygen atoms, which are in turn bonded to the central phosphorus atom, making it a phosphate ester. Recognizing these structures helps when encountering similar compounds where the alkyl groups can vary.

Triethyl Phosphite

Triethyl phosphite is another derivative of phosphorus where the phosphorus atom is bonded to three ethoxy groups, however, it also includes a phosphorus-oxygen double bond which characterizes phosphites. It has the chemical formula \( O=P(OCH_2CH_3)_3 \).

The 'phosphite' designation is crucial to understanding the difference between phosphates and phosphites. The presence of the double bond to oxygen is what sets triethyl phosphite apart from its phosphate counterpart. It is widely used as a ligand in organometallic chemistry as well as an intermediate in the synthesis of insecticides and plasticizers. When naming such compounds, it is important to look for the \( =O \) group attached to phosphorus which denotes a phosphite.

Phosphinoamine

Phosphinoamines incorporate the phosphorus atom bonded to an amine functional group (\( NPR_2 \) where \( N \) represents nitrogen and \( R \) are organic groups). These compounds are valuable due to the combined functionality of phosphine and amine groups.

An example of a phosphinoamine is the compound \( (C_6H_5)_2P-N(C_2H_5)_2 \) which can be named as N,N-diethyl diphenylphosphinoamine. Here, the compound features two phenyl groups (derivatives of benzene) and an amine containing two ethyl substituents attached to nitrogen. Phosphinoamines are used in catalyst systems and the preparation of other complex organophosphorus compounds. When naming, the substituents on the nitrogen and phosphorus are identified, providing a systematic approach to their nomenclature.