31127-80-7

Usage

Chemical Properties

Whitye To Off-White Solid

Uses

5-(Acetamido)-N,N'-bis(2,3-dihydroxypropyl)-2,4,6-triiodo-1,3-benzenedicarboxamide can be used as an intermediate used in the synthesis of imaging agents such as Iohexol (I729500).

Synthetic route

5-acetamido-2,4,6-triiodo-1,3-phthalamide + epichlorohydrin (106-89-8) → N,N'-bis(2,3-dihydroxypropyl)-5-acetamido-2,4,6-triiodoisophthalamide (31127-80-7)

Conditions	Yield
Stage #1: 5-acetamido-2,4,6-triiodo-1,3-phthalamide; epichlorohydrin With 1-hexyl-3-methylimidazolium hexafluorophosphate at 80℃; for 3h; Stage #2: With water at 30℃; for 5h; Reagent/catalyst; Temperature;	97%

5-acetamido-2,4,6-triiodoisophthaloyl dichloride (31122-75-5) + 5-(acetylamino)-N,N'-bis(2,3-dihydroxypropyl)-2,4,6-triiodo-1,3-benzenedicarboxamide sodium salt + 3-Amino-1,2-propanediol (616-30-8, 13552-31-3) → N,N'-bis(2,3-dihydroxypropyl)-5-acetamido-2,4,6-triiodoisophthalamide (31127-80-7)

Conditions	Yield
With hydrogenchloride In methanol; water; 2,4-dichlorophenoxyacetic acid dimethylamine	92%

iohexol (66108-95-0) + 3-monochloro-1,2-propanediol (96-24-2) → N,N'-bis(2,3-dihydroxypropyl)-5-acetamido-2,4,6-triiodoisophthalamide (31127-80-7)

Conditions	Yield
With lithium hydroxide In methanol	92%

5-amino-N,N'-bis(2,3-dihydroxypropyl)-2,4,6-triiodoisophthalamide (76801-93-9) + acetic anhydride (108-24-7) → N,N'-bis(2,3-dihydroxypropyl)-5-acetamido-2,4,6-triiodoisophthalamide (31127-80-7) + 3-(3-acetamido-5-((2,2-dimethyl-1,3-dioxolan-4-yl)methylcarbamoyl)-2,4,6-triiodobenzamido)-propane-1,2-diyl diacetate + 5-acetamido-N,N′-bis-(2,2-dimethyl-1,3-dioxolan-4-yl)methyl-2,4,6-triiodoisophthaldiamide + 3-acetamido-N-(2,3-dihydroxypropyl)-5-(5-hydroxymethyl-2,2-dimethyloxazolidine-3-carbonyl)-2,4,6-triiodobenzamide + 3-acetamido-N-(2,3-dihydroxypropyl)-5-(5-hydroxymethyl-2,2-dimethyloxazolidine-3-carbonyl)-2,4,6-triiodobenzamide

Conditions	Yield
Stage #1: 5-amino-N,N'-bis(2,3-dihydroxypropyl)-2,4,6-triiodoisophthalamide; acetic anhydride With toluene-4-sulfonic acid In acetone for 0.25h; Reflux; Stage #2: With sodium hydroxide In water; acetone	A 70% B 32% C 17% D n/a E n/a

5-amino-N,N'-bis(2,3-dihydroxypropyl)-2,4,6-triiodoisophthalamide (76801-93-9) + acetic anhydride (108-24-7) → N,N'-bis(2,3-dihydroxypropyl)-5-acetamido-2,4,6-triiodoisophthalamide (31127-80-7) + 3-acetamido-N-(2,3-dihydroxypropyl)-5-(5-hydroxymethyl-2,2-dimethyloxazolidine-3-carbonyl)-2,4,6-triiodobenzamide + 3-acetamido-N-(2,3-dihydroxypropyl)-5-(5-hydroxymethyl-2,2-dimethyloxazolidine-3-carbonyl)-2,4,6-triiodobenzamide

Conditions	Yield
Stage #1: 5-amino-N,N'-bis(2,3-dihydroxypropyl)-2,4,6-triiodoisophthalamide; acetic anhydride With toluene-4-sulfonic acid In acetone for 0.25h; Reflux; Stage #2: With sodium hydroxide In water; acetone Stage #3: With sulfuric acid In water; acetone pH=0;	A 70% B n/a C n/a

5-Amino-N,N'-bis[2,3-dihydroxypropyl]-1,3-benzenedicarboxamide (76820-35-4) → N,N'-bis(2,3-dihydroxypropyl)-5-acetamido-2,4,6-triiodoisophthalamide (31127-80-7)

Conditions	Yield
Multi-step reaction with 3 steps 1: Iodine monochloride / 6 h / 50 °C 2: sulfuric acid / water / 50 - 100 °C 3: sodium hydroxide; water / 20 °C / pH 9 - 11 View Scheme

5-nitro-N,N'-bis-(2,3-dihydroxypropyl)isophthalamide (76820-34-3) → N,N'-bis(2,3-dihydroxypropyl)-5-acetamido-2,4,6-triiodoisophthalamide (31127-80-7)

Conditions	Yield
Multi-step reaction with 4 steps 1: 5%-palladium/activated carbon; hydrogen / 70 °C / 9000.9 Torr / Autoclave 2: Iodine monochloride / 6 h / 50 °C 3: sulfuric acid / water / 50 - 100 °C 4: sodium hydroxide; water / 20 °C / pH 9 - 11 View Scheme

dimethyl 5-nitroisophthalate (13290-96-5) → N,N'-bis(2,3-dihydroxypropyl)-5-acetamido-2,4,6-triiodoisophthalamide (31127-80-7)

Conditions	Yield
Multi-step reaction with 5 steps 1: sodium methylate / methanol / 20 - 50 °C 2: 5%-palladium/activated carbon; hydrogen / 70 °C / 9000.9 Torr / Autoclave 3: Iodine monochloride / 6 h / 50 °C 4: sulfuric acid / water / 50 - 100 °C 5: sodium hydroxide; water / 20 °C / pH 9 - 11 View Scheme

N,N'-bis(2,3-dihydroxypropyl)-5-acetamido-2,4,6-triiodoisophthalamide (31127-80-7) + epichlorohydrin (106-89-8) → iohexol (66108-95-0) + iodixanol (92339-11-2)

Conditions	Yield
With hydrogenchloride; boric acid; potassium hydroxide In water pH=10 - 11; Product distribution / selectivity; Industry scale;	A 7.5% B 86.3%
Stage #1: N,N'-bis(2,3-dihydroxypropyl)-5-acetamido-2,4,6-triiodoisophthalamide With sodium hydroxide In methanol at 45℃; Stage #2: epichlorohydrin With hydrogenchloride In methanol at 20℃; for 48h; Product distribution / selectivity;	A 7.42% B 52.1%
With hydrogenchloride; sodium hydroxide In water at 20℃; for 48h; pH=12.2 - 12.7;	A 5.1% B 43.5%

1-azido-2,3-epoxypropane (80044-09-3) + N,N'-bis(2,3-dihydroxypropyl)-5-acetamido-2,4,6-triiodoisophthalamide (31127-80-7) → C19H25I3N6O8 (1309926-44-0)

Conditions	Yield
With boric acid; sodium hydroxide In methanol; water at 40℃; for 6h;	70%

N,N'-bis(2,3-dihydroxypropyl)-5-acetamido-2,4,6-triiodoisophthalamide (31127-80-7) + epichlorohydrin (106-89-8) → iodixanol (92339-11-2)

Conditions	Yield
With hydrogenchloride; sodium hydroxide In 2-methoxy-ethanol; water at 20℃; for 192h; Product distribution / selectivity;	69.1%
Stage #1: N,N'-bis(2,3-dihydroxypropyl)-5-acetamido-2,4,6-triiodoisophthalamide With sodium hydroxide In 1-methoxy-2-propanol; water at 15 - 55℃; Stage #2: epichlorohydrin With hydrogenchloride In 1-methoxy-2-propanol at 15℃; Product distribution / selectivity;	59.4%
Stage #1: N,N'-bis(2,3-dihydroxypropyl)-5-acetamido-2,4,6-triiodoisophthalamide With sodium hydroxide In methanol at 45℃; Stage #2: epichlorohydrin With hydrogenchloride In methanol at 10℃; for 48h;	46.8%

3-chloro-2-hydroxy-1-propyl acetate (24573-30-6) + N,N'-bis(2,3-dihydroxypropyl)-5-acetamido-2,4,6-triiodoisophthalamide (31127-80-7) → 3-(N-(2,5-bis((2,3-dihydroxypropyl)carbamoyl)-2,4,6-triiodophenyl)acetamido)--2-hydrooxypropylacetate

Conditions	Yield
With sodium methylate In N,N-dimethyl acetamide at 20℃; for 18h; pH=11.5 - 12; pH-value; Reagent/catalyst; Solvent; Temperature;	63%

N,N'-bis(2,3-dihydroxypropyl)-5-acetamido-2,4,6-triiodoisophthalamide (31127-80-7) + tert-butyl N-(2-oxiranylmethyl)carbamate (148982-76-7, 149057-20-5, 115198-80-6) → 5-[Acetyl-(3-amino-2-hydroxy-propyl)-amino]-N,N'-bis-(2,3-dihydroxy-propyl)-2,4,6-triiodo-isophthalamide (1150307-23-5)

Conditions	Yield
Stage #1: N,N'-bis(2,3-dihydroxypropyl)-5-acetamido-2,4,6-triiodoisophthalamide With potassium hydroxide In water; tert-butyl alcohol at 40℃; Stage #2: With boric acid In water; tert-butyl alcohol Stage #3: tert-butyl N-(2-oxiranylmethyl)carbamate With hydrogenchloride; potassium hydroxide more than 3 stages;	19%
With hydrogenchloride; potassium hydroxide; boric acid In water; tert-butyl alcohol	19%

2-chloromethyl-2-methyloxiran (598-09-4) + N,N'-bis(2,3-dihydroxypropyl)-5-acetamido-2,4,6-triiodoisophthalamide (31127-80-7) → 5,5'-(2-hydroxy-2-methylpropane-1,3-diyl)bis(acetylazanediyl)bis(N1,N3-bis(2,3-dihydroxypropyl)-2,4,6-triiodoisophthalamide) (1186057-94-2)

Conditions	Yield
Stage #1: 2-chloromethyl-2-methyloxiran; N,N'-bis(2,3-dihydroxypropyl)-5-acetamido-2,4,6-triiodoisophthalamide With boric acid; potassium hydroxide In methanol; water at 20℃; pH=12.6 - 13; Stage #2: With hydrogenchloride In methanol; water pH=4;	3%

1-chloro-3-methoxypropan-2-ol (4151-97-7) + N,N'-bis(2,3-dihydroxypropyl)-5-acetamido-2,4,6-triiodoisophthalamide (31127-80-7) → N,N'-bis(2,3-dihydroxypropyl)-5-[N-(2-hydroxy-3-methoxypropyl)acetamido]-2,4,6-triiodoisophthalamide + 5-[Acetyl-(2-hydroxy-3-methoxy-propyl)-amino]-N,N'-bis-(2,3-dihydroxy-propyl)-N-(2-hydroxy-3-methoxy-propyl)-2,4,6-triiodo-isophthalamide + 5-[Acetyl-(2-hydroxy-3-methoxy-propyl)-amino]-N-(2,3-dihydroxy-propyl)-N'-[3-hydroxy-2-(2-hydroxy-3-methoxy-propoxy)-propyl]-2,4,6-triiodo-isophthalamide + 5-[Acetyl-(2-hydroxy-3-methoxy-propyl)-amino]-N-(2,3-dihydroxy-propyl)-N'-[2-hydroxy-3-(2-hydroxy-3-methoxy-propoxy)-propyl]-2,4,6-triiodo-isophthalamide

Conditions	Yield
With sodium hydroxide; calcium chloride multistep reaction; cationic influence on the N/O alkylation selectivity; various metals chloride; var. concentr., var. reaction times and temperatures;	A 83.85 % Chromat. B n/a C n/a D n/a

N,N'-bis(2,3-dihydroxypropyl)-5-acetamido-2,4,6-triiodoisophthalamide (31127-80-7) + 5--N,N'-bis(2,3-dihydroxypropyl)-2,4,6-triiodoisophthalamide (171897-76-0) → 5,5'-(N-acetyl-2-hydroxypropane-1,3-diyldiamino)bis

Conditions	Yield
In water for 48h; Ambient temperature; pH=12.0;

N,N'-bis(2,3-dihydroxypropyl)-5-acetamido-2,4,6-triiodoisophthalamide (31127-80-7) + 3-monochloro-1,2-propanediol (96-24-2) + butan-1-ol (71-36-3) → iohexol (66108-95-0)

Conditions	Yield
With sodium hydroxide; Ca(OH)2 In water
With sodium hydroxide; Ca(OH)2 In water

N,N'-bis(2,3-dihydroxypropyl)-5-acetamido-2,4,6-triiodoisophthalamide (31127-80-7) → iohexol (66108-95-0)

N,N'-bis(2,3-dihydroxypropyl)-5-acetamido-2,4,6-triiodoisophthalamide (31127-80-7) + oxiranyl-methanol (556-52-5) → iohexol (66108-95-0)

Conditions	Yield
With potassium hydroxide In methanol; dimethyl sulfoxide; isopropyl alcohol
Stage #1: N,N'-bis(2,3-dihydroxypropyl)-5-acetamido-2,4,6-triiodoisophthalamide With boric acid; potassium hydroxide In water at 10℃; for 48h; pH=12.4; Stage #2: oxiranyl-methanol In water at 10℃; for 24h; pH=12.6-13; Time; pH-value;

N,N'-bis(2,3-dihydroxypropyl)-5-acetamido-2,4,6-triiodoisophthalamide (31127-80-7) + 3-monochloro-1,2-propanediol (96-24-2) → iohexol (66108-95-0)

Conditions	Yield
With sodium methylate In propylene glycol
Stage #1: N,N'-bis(2,3-dihydroxypropyl)-5-acetamido-2,4,6-triiodoisophthalamide With sodium hydroxide In methanol; 1-methoxy-2-propanol at 25 - 45℃; Stage #2: 3-monochloro-1,2-propanediol In methanol; 1-methoxy-2-propanol at 25℃; for 25.5h; Product distribution / selectivity;
Stage #1: N,N'-bis(2,3-dihydroxypropyl)-5-acetamido-2,4,6-triiodoisophthalamide With sodium hydroxide In 1-methoxy-2-propanol; water at 25 - 45℃; Stage #2: 3-monochloro-1,2-propanediol In 1-methoxy-2-propanol; water at 35℃; for 27h; Product distribution / selectivity;

N,N'-bis(2,3-dihydroxypropyl)-5-acetamido-2,4,6-triiodoisophthalamide (31127-80-7) → C29 (70894-76-7)

Conditions	Yield
In methanol; chloroform
	3.8 g (45%)

1,3-diiodo-2-(iodomethyl)propane (66587-78-8) + N,N'-bis(2,3-dihydroxypropyl)-5-acetamido-2,4,6-triiodoisophthalamide (31127-80-7) → tris(N-acetyl-N-(3,5-bis(2',3'-dihydroxypropylaminocarbonyl)-2,4,6-triiodophenyl)aminomethyl)methane

Conditions	Yield
Stage #1: 1,3-diiodo-2-(iodomethyl)propane; N,N'-bis(2,3-dihydroxypropyl)-5-acetamido-2,4,6-triiodoisophthalamide With potassium hydroxide; boric acid In methanol; water at 10 - 40℃; for 48h; Stage #2: In methanol; water pH=3.5;

Upstream product

• 31122-75-5 5-acetamido-2,4,6-triiodoisophthaloyl dichloride 
• 616-30-8 3-Amino-1,2-propanediol 
• 66108-95-0 iohexol 
• 96-24-2 3-monochloro-1,2-propanediol 
• 37441-29-5 5-amino-2,4,6-triiodoisophthalic acid dichloride 
• 76801-93-9 5-amino-N,N'-bis(2,3-dihydroxypropyl)-2,4,6-triiodoisophthalamide 
• 108-24-7 acetic anhydride 
• 64-19-7 acetic acid 
• 174416-65-0 C₂₄H₂₈I₃N₃O₁₁ 
• 76820-35-4 5-Amino-N,N'-bis[2,3-dihydroxypropyl]-1,3-benzenedicarboxamide 
• 76820-34-3 5-nitro-N,N'-bis-(2,3-dihydroxypropyl)isophthalamide 
• 13290-96-5 dimethyl 5-nitroisophthalate 
• 106-89-8 epichlorohydrin 

Downstream Products

• 89797-00-2 N,N'-bis(2,3-dihydroxypropyl)-5-[N-(2-hydroxy-3-methoxypropyl)acetamido]-2,4,6-triiodoisophthalamide 
• 66108-95-0 iohexol 
• 92339-11-2 iodixanol 
• 171897-74-8 5,5'-(N-acetyl-2-hydroxypropane-1,3-diyldiamino)bis 
• 70894-76-7 C₂₉ 
• 1186057-94-2 5,5'-(2-hydroxy-2-methylpropane-1,3-diyl)bis(acetylazanediyl)bis(N₁,N₃-bis(2,3-dihydroxypropyl)-2,4,6-triiodoisophthalamide) 
• 1309926-44-0 C₁₉H₂₅I₃N₆O₈ 
• 1150307-18-8 C₃₂H₃₈I₆N₆O₁₄ 
• 1309926-45-1 C₃₄H₆₅I₃N₆O₈Si₅ 
• 1309926-46-2 C₃₄H₆₇I₃N₄O₈Si₅ 
• 1150307-23-5 5-[Acetyl-(3-amino-2-hydroxy-propyl)-amino]-N,N'-bis-(2,3-dihydroxy-propyl)-2,4,6-triiodo-isophthalamide 
• 1048964-64-2 N,N,N'-tris-(3-{acetyl-[3,5-bis-(2 3-dihydroxy-propyl-carbamoyl)-2,4,6-triiodo-phenyl]-amino}-2-hydroxy-propyl)-dicarbonimidic diamide 

Relevant academic research and scientific papers

Preparation method of iodixanol hydrolysate

The invention discloses a preparation method of an iodixanol hydrolysate. The preparation method comprises the following steps: in ionic liquid, condensing and hydrolyzing 5-acetamido-2,4,6-triiodo-1,3-benzenedicarboxamide and epoxy chloropropane under the action of a solid base catalyst to obtain the product 5-(acetamido)-N,N'-bis(2,3-dihydroxypropyl)-2,4,6-triiodo-1,3-benzenedicarboxamide, wherein the solid base catalyst takes a metal oxide as a first active component, takes one or more of corresponding metal hydroxide, carbonate and bicarbonate as a second active component, and takes strongly basic anion exchange resin as a carrier. The catalyst is simple in preparation process, good in activity, long in service cycle, high in product yield, good in purity and free of trace impurities limited by drugs. Equipment is not corroded in the production process, product post-treatment is convenient, the production cost is low, and the method is economical, practical, green and environmentally friendly.

Contrast medium of the impurity F synthetic method and its impurity G contrast medium, impurity H and impurity M application in the synthesis of

The invention relates to a synthesis method of contrast medium impurities, in particular to a contrast medium impurity F synthetic method and its in the contrast medium impurity G, impurity H and M application in the synthesis of the impurity, which belongs to the field of medical technology. The method is to 5 - nitro - 1, 3 - benzene dicarboxylic acid dimethyl ester (formula 2 compound) and 2, 3 - dihydroxy propylamine as raw materials of formula 3 compound, type 3 compound with hydrogen reduction reaction [...] 4 compound, of formula 4 with a compound obtained by reaction of the impurity F [...] contrast medium. The invention relates to 5 - nitro - 1, 3 - benzene dicarboxylic acid dimethyl ester (formula 2 compound) as the starting material, the synthesis of 5 - amino - N, double-N' - (2, 3 - dihydroxy-propyl) - diiodo - 1, 3 - benzene dicarboxylic amide (formula 1 compounds) and then to of formula 1 as the starting material for the synthesis of impurity G, impurity H and impurity M, for the contrast medium quality control to provide acceptable impurity reference substance.

Novel energy-saving environment-friendly continuous preparation method of iohexol

The invention relates to a novel energy-saving environment-friendly continuous preparation method of iohexol. The preparation method specifically comprises the following steps: (1) acylation reaction:carrying out a reaction on a compound of a formula [2] with acetic anhydride in an environment of hydrochloric acid to obtain a compound of a formula [3]; (2) transesterification: carrying out a reaction on the compound of the formula [3] with a small-molecule liquid alcohol under an appropriate condition to obtain a compound of a formula [4], (3) alkylation reaction: carrying out a reaction on the compound of the formula [4] with 3-chloro-1,2-propylene glycol under the condition of a mixed solution of methanol and sodium methoxide, carrying out neutralization, filtering and desolvation to obtain an iohexol crude product; (4) purification: purifying the iohexol crude product to obtain an iohexol pure product. The method comprises carrying out the transesterification reaction on the liquidalcohol with 5-acetylamino-2,4,6-triiodo-N,N'-bis(2,3-diacetoxypropyl)-1,3-phthalamide, then carrying out an alkylation reaction with the alkylating reagent 3-chloro-1,2-propylene glycol in a methanol solution of the sodium methoxide, carrying out neutralization by using a methanol solution of hydrochloric acid, carrying out filtering, carrying out desolvation on the obtained filtrate, and thenpurifying the obtained iohexol crude product to obtain the iohexol pure product.

Energy-saving environment-friendly continuous preparation method of iohexol

The invention relates to an energy-saving environment-friendly continuous preparation method of iohexol. The preparation method comprises the following steps: (1) acylation reaction: carrying out a reaction on a compound of a formula [2] with acetic anhydride in an environment of hydrochloric acid to obtain a compound of a formula [3]; (2) transesterification: carrying out a reaction on the compound of the formula [3] with a small-molecule liquid alcohol under an appropriate conditions to obtain a compound of a formula [4]; (3) alkylation reaction: carrying out a reaction on the compound of the formula [4] with and 3-chloro-1,2-propanediol under a condition of a mixed solution of methanol and sodium methoxide to obtain an iohexol crude product; and (4) purification: purifying the iohexol crude product to obtain an iohexol pure product. According to method, the transesterification reaction is carried out on the liquid alcohol with 5-acetylamino-2,4,6-triiodo-N,N'-bis(2,3-diacetoxypropyl)-1,3-phthalamide, then the alkylation reaction is carrred out with the alkylation reagent 3-chloro-1,2-propanediol in a methanol solution of the sodium methoxide, and the obtained iohexol crude product is purified to obtain the pure iohexol product.

MECHANOCHEMICAL SYNTHESIS OF RADIOGRAPHIC AGENTS INTERMEDIATES

The present invention generally relates to a process using a mechanochemical approach exploiting the mechanical milling of reactants for the manufacturing of acetyl Iopamidol and, more generally, of key intermediates of radiographic contrast agents, and of the contrast agents themselves.

ALTERNATIVE ACETYLATION PROCESS IN THE SYNTHESIS OF NON-IONIC XRAY CONTRAST AGENTS

An alternative acetylation process for the synthesis of 5-acetamido-N,N'-bis(2,3-dihydroxypropyl)-2,4,6-triiodoisophthalamide ( Compound A ), an intermediate in the industrial preparation of non-ionic X-ray contrast agents, is described. The process can be performed on an industrial scale to produce Compound A with improved purity and improved yields compared to the established processes.

Formation of N,O-acetalsin the production of x-ray contrast agents

Acetylation of 1 with acetic anhydride, an important step in the preparation of iohexol, gave the corresponding acetanilide and minor amounts of a few byproducts, whose structures have been elucidated. Among the byproducts were some 1,3-oxazolidines which survived when the reaction was quenched by adding methanol and water under strong acidic conditions.

PREPARATION OF INTERMEDIATES OF X-RAY CONTRAST AGENTS

The present invention relates to a process for the preparation of iodinated X-ray contrast agents and in particular to key intermediates thereof. It particularly relates to an improved process for preparation of 5-acetamido-N,N'-bis(2,3-dihydroxypropyl)-2,4,6-triiodoisophthalamide (Compound A) or N,N'-bis(2,3-dihydroxypropyl)-5-formamido-2,4,6-triiodoisophthalamide (Compound C), which are intermediates in the industrial preparation of non-ionic X-ray contrast agents. More particularly the invention provides a process for deacylation of the acylated hydroxyl groups of an intermediate compound of Compound A and Compound C.

A continuous deacetylation and purification process in the synthesis of non-ionic X-ray contrast agents

This invention relates to an improved method for the synthesis of 5-acetamido-N,N'-bis(2,3-dihydroxypropyl)-2,4,6-triiodoisophthalamide ("Compound A"), an intermediate in the industrial preparation of non-ionic X-ray contrast agents. In particular, it relates to a continuous process of deacetylation of the acetylated hydroxyl group in 5-amino-N,N'-bis(2,3-dihydroxypropyt)-2,4,6-triiodo-1,3-benzenedicarboxarriide ("Compound B") followed by crystallisations, filtration, and washing of Compound A.

A continuous acetylation process in the synthesis of non-ionic X-ray contrast agents

This invention relates to a method for the synthesis of 5-acetamido-N,N'-bis(2,3-dihydroxypropyl)-2,4,6-triiodoisophthalamide ("Compound A"), an intermediate in the industrial preparation of non-ionic X-ray contrast agents. In particular, it relates to a continuous process of acetylation of 5-amino-N,N'-bis(2,3-dihydroxypropyl)-2,4,6-triiodo-1,3-benzenedicarboxamide ("Compound B") followed by the removal of acetic anhydride.