Organic Chemistry Past Paper PDF
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Helwan University
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Summary
This document outlines various tests for identifying aliphatic and aromatic acids, along with their mixtures. A detailed procedure for solubility tests and other tests such as Molisch's test and Fehling's test are included in the document.
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## Mix ### Aliphatic and Aromatic Acids **Aliphatic acids:** soluble in H<sub>2</sub>O - Oxalic: COOH - Tartaric: HO-CH-COOH, HO-CH-COOH - Citric: H<sub>2</sub>C-COOH, HO-C-COOH, H<sub>2</sub>C-COOH **Aromatic acids:** insoluble in H<sub>2</sub>O - Salicylic: COOH - Benzoic: COOH - Phthalic:...
## Mix ### Aliphatic and Aromatic Acids **Aliphatic acids:** soluble in H<sub>2</sub>O - Oxalic: COOH - Tartaric: HO-CH-COOH, HO-CH-COOH - Citric: H<sub>2</sub>C-COOH, HO-C-COOH, H<sub>2</sub>C-COOH **Aromatic acids:** insoluble in H<sub>2</sub>O - Salicylic: COOH - Benzoic: COOH - Phthalic: - COO - COOH ### Solubility Test | Mixture | Result | |---------------------|--------------------| | Mix + H<sub>2</sub>O | *Completely Soluble* | *Completely Insoluble* | *Partially Soluble* | | | **(Aliphatic + Aliphatic)** | **(Aromatic + Aromatic)** | **(Aliphatic + Aromatic)** | #### Filteration ##### Filteration of Aliphatic 1. **Make Neutral Solution** 2. **Filterate + NH₄OH** 3. **+ CaCl₂ Solution** **Results:** - White precipitate immediately: **Oxalic** - White precipitate after scratching: **Tartaric** - White precipitate after boiling: **Citric** ##### Filteration of Aromatic 1. **Make Neutral Solution** 2. **Ppt + NH₄OH** 3. **+ FeCl₃ Solution** **Results** - Buff: **Benzoic** - Violet: **Salicylic** ### Molisch's Test **Aliphatic acid + Carbohydrate = Positive (Violet Ring)** **Aromatic acid + Carbohydrate = Negative** ### Solubility Test | Mixture | Result | |------------------------|-----------------------| | Mix + H<sub>2</sub>O | *Completely Soluble* | *Partially Soluble* | *Completely in Soluble* | | | **(Aliphatic acid + mono or disaccharide)** | **(Aliphatic acid + Starch) / (Aromatic acid + mono or disaccharide)** | **(Aromatic acid + Starch)** | #### Confirmation **Mix + I₂:** - **if Dark Blue is formed:** Aliphatic acid + Starch - **if no dark blue is formed:** Aromatic acid + mono or disaccharide ### A-N + Molisch's #### IF DARK BLUE IS FORMED : (Mix is Aliphatic acid + starch) ##### Solubility Test | Mixture | Result | |-----------------------|-------------| | Mix + H<sub>2</sub>O | *PPT* | | | *Starch* | **How to filter:** 1. **Filterate Aliphatic acid (Neutral Solution)** 2. **Filterate + NH₄OH** 3. **+ CaCl₂ Solution** **Results:** - White precipitate immediately: **Oxalic** - White precipitate after scratching: **Tartaric** - White precipitate after boiling: **Citric** #### IF NO DARK BLUE IS FORMED : (Mix is Aromatic acid + mono or disaccharide) ##### Solubility Test | Mixture | Result | |------------------------|-------------| | Mix + H<sub>2</sub>O | *PPT* | | | *mono or disaccharide* | **How to filter:** 1. **Filterate Aromatic acid (Neutral Solution)** 2. **PPT + NH₄OH** 3. **+ FeCl₃ Solution** **Results:** - Buff: **Benzoic** - Violet: **Salicylic** ### Filterate (mono or disaccharide) #### Barfoed Test - **Filterate to Barfoed regent + drops of conc. H₂SO₄** - **A on Flame** | Result | Conclusion | |--------|-----------------------| | +ve (red Color) | Monosaccharide | | | Glucose or Fructose | | -ve | Disaccharide | | | Maltose, Lactose, or Sucrose | #### Furfural Test 1. **Mix + H₂O + take filterate** 2. **Filterate + Molisch + conc. HCl + to boiling** | Result | Conclusion | |----------------|-----------------| | Violet color immediately | Fructose | | Violet colour after time | Glucose | ##### Confirmation 1. **Mix + H₂O + take filterate** 2. **Filterate + lead acetate** 3. **+ NH₄OH** **Results:** - Pink: **Glucose** - Violet: **Fructose** #### Fehling's Test 1. **Mix + H₂O + take filterate** 2. **Filterate + Fehling (A+B)** | Result | Conclusion | |-------------------|-----------------| | +ve (red to brown) | Lactose or Maltose | | +ve | Sucrose | ##### Confirmation 1. **Mix + H₂O + take filterate** 2. **Filterate + lead acetate** 3. **+ NH₄OH** **Results:** - Pink: **Maltose** - Yellow: **Lactose** ### Solubility Test | Mixture | Result | |----------------------|------------| | *Completely Soluble* | Mix (Aliphatic acid + Salt of aromatic) | | *Partially Soluble* | (1-Aliphatic acid + Insoluble neutral) OR / (2-Aromatic acid + Salt of aliphatic) | | *Completely in Soluble* | Mix (Aromatic acid + Insoluble neutral) | **How to filter:** 1. **Filterate Aromatic** 2. **Neutral solution** 3. **Filterate + NH₄OH** 4. **+ FeCl₃ Solution** **Results:** - Buff: **Benzoate Salicylate** - Violet: **Salicylic** #### How to Identify Which Mix You Have? - If you can see a **furance,** it’s likely you have **Mix (Aliphatic acid + Insoluble neutral)** - If there is **no furance,** then it’s likely you have **Mix (Aromatic acid + Salt of Aliphatic)** ### Solubility Test | Mixture | Result | |--------------------|-------------| | Mix + H<sub>2</sub>O | *PPT* | | | *Insoluble neutral* | **How to filter:** 1. **Filterate Aliphatic acid (Neutral Solution)** 2. **Filterate + NH₄OH** 3. **+ CaCl₂ Solution** **Results:** - White precipitate immediately: **Oxalic** - White precipitate after scratching: **Tartaric** - White precipitate after boiling: **Citric** - Red: **Anthracene** - Yellow: **Napthalene** #### How to Identify Which Mix You Have? - If you can see a **furance,** it’s likely you have **Mix (Aliphatic acid + Insoluble neutral)** - If there is **no furance,** then it’s likely you have **Mix (Aromatic acid + Salt of Aliphatic)** ### Solubility Test | Mixture | Result | |-----------------------|------------------| | Mix + H<sub>2</sub>O | *PPT* | | | *Aromatic acid* | | | *Neutral Solution* | **How to filter:** 1. **Filterate Salt of Aliphatic (Neutral Solution)** 2. **Filterate + NH₄OH** 3. **+ FeCl₃ Solution** **Results:** - White precipitate immediately: **Oxalate** - White precipitate after scratching: **Tartarate** - White precipitate after boiling: **Citrate** - Buff: **Benzoic** - Violet: **Salicylic**
