Process for making iminodiacetic acid compounds from monoethanolamine substrates

A process for making an iminodiacetic acid compound from a monoethanolamine substrate, the process comprising:

• continuously or intermittently introducing said monoethanolamine substrate into a cyanomethylation reaction zone;
• continuously or intermittently contacting said monoethanolamine substrate with a source of formaldehyde and a source of cyanide in said cyanomethylation reaction zone to form a cyanomethylation product comprising a N-cyanomethylated monoethanolamine intermediate;
• continuously or intermittently introducing at least a portion of said N-cyanomethylated monoethanolamine intermediate from said cyanomethylation product into a hydrolysis reaction zone;
• continuously or intermittently contacting said N-cyanomethylated monoethanolamine intermediate with a hydroxide source in said hydrolysis reaction zone to form a hydrolysis product comprising an N-(2-hydroxyethyl)glycine intermediate;
• continuously or intermittently introducing at least a portion of said N-(2-hydroxyethyl)glycine intermediate from said hydrolysis product into a dehydrogenation reaction zone;
• and
• continuously or intermittently contacting said N-(2-hydroxyethyl)glycine intermediate with a metal-containing catalyst in said dehydrogenation reaction zone to form a dehydrogenation product comprising an iminodiacetic acid compound,
• wherein said monoethanolamine substrate has the formula:
• R1 is hydrogen, hydrocarbyl, or substituted hydrocarbyl.

A process for making disodium iminodiacetic acid from 2-aminoethanol, the process comprising:

• continuously or intermittently introducing said 2-aminoethanol into a cyanomethylation reaction zone;
• continuously or intermittently contacting said 2-aminoethanol with a cyanide source and a formaldehyde source in said cyanomethylation reaction zone to form a cyanomethylation product comprising 2-(N-cyanomethylamino)ethanol;
• continuously or intermittently introducing at least a portion of said 2-(N-cyanomethylamino)ethanol from said cyanomethylation product into a hydrolysis/dehydrogenation reaction zone;
• and
• continuously or intermittently contacting said 2-(N-cyanomethylamino)ethanol with sodium hydroxide and a metal-containing catalyst in said hydrolysis/dehydrogenation reaction zone to form a hydrolysis/dehydrogenation product comprising disodium iminodiacetic acid.

A process for making disodium iminodiacetic acid from 2-aminoethanol, the process comprising:

• continuously or intermittently introducing said 2-aminoethanol into a cyanomethylation reaction zone;
• continuously or intermittently contacting said 2-aminoethanol with a source of cyanide and a source of formaldehyde in said cyanomethylation reaction zone to form a cyanomethylation product comprising 2-(N-cyanomethylamino)ethanol;
• continuously or intermittently introducing at least a portion of said 2-(N-cyanomethylamino)ethanol from said cyanomethylation product into a hydrolysis reaction zone;
• continuously or intermittently contacting said 2-(N-cyanomethylamino)ethanol with sodium hydroxide in said hydrolysis reaction zone to form a hydrolysis product comprising sodium N-(2-hydroxyethyl) glycinate;
• continuously or intermittently introducing at least a portion of said sodium N-(2-hydroxyethyl)glycinate from said hydrolysis product into a dehydrogenation reaction zone;
• and
• continuously or intermittently contacting said sodium N-(2-hydroxyethyl)glycinate with a metal-containing catalyst in said dehydrogenation reaction zone to form a dehydrogenation product comprising disodium iminodiacetic acid.