Fix reaction SMILES parsing and examples

app.py

@@ -190,16 +190,53 @@ def smiles_to_name(smiles: str) -> str:
 def reaction_smiles_to_svg(reaction_smiles: str) -> str:
     """Convert reaction SMILES to SVG image"""
     try:
-        # Parse the reaction SMILES
-        reaction = rdChemReactions.ReactionFromSmarts(reaction_smiles)
-        if reaction is None:
-            raise gr.Error(f"Invalid reaction SMILES: {reaction_smiles}")
+        # Parse the reaction SMILES - try ReactionFromSmarts first, fallback to manual parsing
+        try:
+            reaction = rdChemReactions.ReactionFromSmarts(reaction_smiles)
+        except:
+            # If ReactionFromSmarts fails, try to parse manually
+            if ">>" not in reaction_smiles:
+                raise gr.Error("Reaction SMILES must contain '>>' to separate reactants from products")
+            
+            parts = reaction_smiles.split(">>")
+            if len(parts) != 2:
+                raise gr.Error("Reaction SMILES must have exactly one '>>' separator")
+            
+            reactant_smiles = parts[0].strip()
+            product_smiles = parts[1].strip()
+            
+            # Create reaction from individual molecules
+            reactant_mols = []
+            for smi in reactant_smiles.split('.'):
+                smi = smi.strip()
+                if smi:
+                    mol = Chem.MolFromSmiles(smi)
+                    if mol is None:
+                        raise gr.Error(f"Invalid SMILES in reactants: {smi}")
+                    reactant_mols.append(mol)
+            
+            product_mols = []
+            for smi in product_smiles.split('.'):
+                smi = smi.strip()
+                if smi:
+                    mol = Chem.MolFromSmiles(smi)
+                    if mol is None:
+                        raise gr.Error(f"Invalid SMILES in products: {smi}")
+                    product_mols.append(mol)
+            
+            reaction = rdChemReactions.ChemicalReaction()
+            for mol in reactant_mols:
+                reaction.AddReactantTemplate(mol)
+            for mol in product_mols:
+                reaction.AddProductTemplate(mol)
 
         # Draw the reaction as SVG
         svg = Draw.ReactionToImage(reaction, subImgSize=(300, 300), useSVG=True)
         
         return svg
 
+    except gr.Error:
+        raise
     except Exception as e:
         raise gr.Error(f"Error generating reaction image: {str(e)}")
 
@@ -1301,7 +1338,7 @@ reaction_interface = gr.Interface(
     fn=reaction_smiles_to_svg,
     inputs=gr.Textbox(
         label="Reaction SMILES",
-        placeholder="CCO.O=C=O>>CC(=O)O.CO2 (Esterification reaction)",
+        placeholder="CCO.O=C=O>>CC(=O)O.O=C=O (Esterification reaction)",
         info="Use '>>' to separate reactants from products"
     ),
     outputs=gr.HTML(label="Reaction Visualization"),
@@ -1309,9 +1346,9 @@ reaction_interface = gr.Interface(
     description="Visualize chemical reactions from SMILES notation.",
     api_name="reaction_visualizer",
     examples=[
-        ["CCO.O=C=O>>CC(=O)O.CO2"],
-        ["c1ccccc1.ClC(Cl)Cl>>c1ccccc1Cl.HCl"],
-        ["CC(=O)O.[Na]>>CC(=O)O[Na]"]
+        ["CC(=O)O.CO>>CC(=O)OC.O"],
+        ["c1ccccc1.ClCl>>c1ccccc1Cl.Cl"],
+        ["Cl.[Na+].[OH-]>>[Na+].[Cl-].O"]
     ],
 )