Write the structure for a compound with the molecular formula C4H₂O that would not be expected to exhibit a broad and strong infrared absorption over the range of 3200-3550 cm ¹ and 1620-1780 cm ¹ regions.

Molecular Recognition (Supramolecular Chemistry) in organic chemistry deals with the "lock and key " mechanisms  that form new molecules. However, little is known of this subject when moleules go beyond 1500 daltons (g/mole) for example macromolecules of polyolefins (polyethylene, polypropylene), thermoplastic polyesters and polyamides (nylon). It is understood that pre-directional H bonding is the mechanism of molecular recognition of macromolecules. Question: What is the immediate and post manifestation of inducing molecular recognition to condensation polymers and ring opening polymerization polymers like thermoplastic polyesters (PET ), and Nylon 66, 6 etc. (polyamides)?

In infrared spectra, the O-H vibrational frequency of alcohols occurs as a broad peak (peak absorbable) in the region 3200-3600 cm -1, true or false?

7. Consider the C=O stretching data for the following cyclic ketones: cyclopropane 1813 cm³¹; cyclobutanone 1791 cm³¹; cyclopentanone 1740 cm³¹. (a) which ketone has the strongest bond? (b) where in the trend would you expect the C=O stretch of cyclopropenone? (Use the hybridization information in the same way we used hybridization for C-H stretching.)