Question

POST-LAB GUIDE QUESTIONS 1) How does formaldehyde act as disinfectant or as a preservative of biological specimens? 2) What are the uses of urotropine? Give its structure. Explain the action of each. 3) is the use of HCHO as a food preservative permitted by law? Explain. 4) Give the practical use of the reduction of AgNO3 by means of aldehydes. 5) What is paraldehyde? Give one use of paraldehyde in medicine, 6) Give the commercial use of acetone. 7) What is the presence of acetone in urine and breath an indication of? 8) What is meant by autooxidation? 9) Formaldehyde undergoes addition reactions more readily than all of other aldehyde, Explain why. 10) Predict the product/s formed when aldehydes and ketones undergo aldol condensation. Complete the equation below and provide a name to the products formed.

Answer 1

ANS-:1.

An aqueous solution of formaldehyde can be useful as a disinfectant as it kills most bacteria and fungi (including their spores).

ANS-:2

Hexamethylenetetramine or methenamine, also known as hexamine or urotropin, is a heterocyclic organic compound with the formula (CH₂)₆N₄. This white crystalline compound is highly soluble in water and polar organic solvents. It has a cage-like structure similar to adamantane

ACTION-As the mandelic acid salt (generic methenamine mandelate, ) it is used for the treatment of urinary tract infection. It decomposes at an acidic pH to form formaldehyde and ammonia, and the formaldehyde is bactericidal; the mandelic acid adds to this effect. Urinary acidity is typically ensured by co-administering vitamin C (ascorbic acid) or ammonium chloride. Its use had temporarily been reduced in the late 1990s, due to adverse effects, particularly chemically-induced hemorrhagic cystitis in overdose, but its use has now been re-approved because of the prevalence of antibiotic resistance to more commonly used drugs. This drug is particularly suitable for long-term prophylactic treatment of urinary tract infection, because bacteria do not develop resistance to formaldehyde. It should not be used in the presence of chronic kidney disease.

ANS-3:

Formaldehyde can be found naturally in food including fruits, vegetables, meats, marine fish and crustacean, with levels up to 300 to 400 mg/kg. Formaldehyde is used as a food preservative illegally since it can prolong the shelf-life of a food by protecting against deterioration caused by microorganisms.[ NOTE-high enough quantities to make  sick]

ANS-4:

[AgNO₃],Tollens' reagent is a chemical reagent used to determine the presence of an aldehyde or alpha-hydroxy ketone functional groups. The reagent consists of a solution of silver nitrate and Ammonia.

ANS-5:

Paraldehyde is the cyclic trimer of acetaldehyde molecules. Formally, it is a derivative of 1,3,5-trioxane. The corresponding tetramer is metaldehyde. A colourless liquid, it is sparingly soluble in water and highly soluble in ethanol.Formula: C₆H₁₂O₃.It has been used in the treatment of alcoholism and in the treatment of nervous and mental conditions to calm or relax patients who are nervous or tense and to produce sleep.

ANS-6:

[1].Acetone is commonly used as a solvent to manufacture plastics and other industrial products.

2.Acetone may also be used to a limited extent in household products, including cosmetics and personal care products, where its most frequent application would be in the formulation of nail polish removers

ANS-7:

If a person's breath smells very fruity or strongly of acetone, it can indicate DKA. Other symptoms of DKA include: passing urine more often than usual. nausea and vomiting

ANS-8:

There are two reasons for this.

1.the other aldehyde has a comparitively bulky group attached to carbonyl group which hinders the attack of Nucleophile to some extent , but in the case of formaldehyde this is not so.

2. CH3 group in other Aldehyde  decreases the positive charge on cabonyl carbon by +I effect to some extect which is not so in the case of formaldehyde, Since , Nu attack is favourable with more positive charge and less hinderance at carbonyl carbon , hence we conclude that formaldehyde is more reactive than other aldehyde .

ANS-9:

Autoxidation is any oxidation that occurs in presence of oxygen. The term is usually used to describe the degradation of organic compounds in air (as a source of oxygen). ... It can be considered to be a slow, flameless combustion of materials by reaction with oxygen.

ANS-10.The reaction between an aldehyde/ketone and an aromatic carbonyl compound lacking an alpha-hydrogen (cross aldol condensation) is called the Claisen-Schmidt condensation.
2= 2) Structure of Urotropin C6H12 Ng - (42 ) Structure of Parraldehyde N 2,4,6 - Trimethyl-1,3,5- trioxame

Cofio ) Aldd 요 CH₂ - C-H Aldehyde (Erhonal Condensation between Aldehyde and ketone 요 Ba 앤 요 + CH3 -C- C43 - Cn₂-c-CH2-C-643 Ketone (Acelone) 4 - Hychoxy penton-2-one. this above Reaction between the one Aldehyle and One ketone
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