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Topic: Functional Group #5-Aldehydes. Do Now: Write the molecular formula for the two sugars on the right. Are they isomers?. O. . General formula: R C H or RCHO Carbonyl group just like ketone except always at end of aldehyde
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Topic: Functional Group #5-Aldehydes Do Now: Write the molecular formula for the two sugars on the right. Are they isomers?
O • General formula: RCH or RCHO • Carbonyl group just like ketone except alwaysat end of aldehyde • Attached to Carbon chain on one side and a H on the other
- O R H H R - - + C=O C=O + + H H Properties = same as ketones Aldehydes are polar! Dissolve in water • Dipole-Dipole interactions • Boiling point: • higher than alkanes (same # C’s) • lower than alcohols (same # C’s)
Acetaldehyde (ethanal) = important aldehyde • Occurs naturally in • Coffee • Bread • Ripe fruit • Produced by plants • Produced by the partial oxidation of ethanol in the liver and may be a contributing factor to hangovers from alcohol consumption • It’s an air pollutant resulting from combustion (car exhaust and cigarette smoke)
Naming • Find name of alkane with same # of C’s • change the -e to -al • Never need #’s for aldehydes • b/c functional group always on end C
HCH O Methanal O H HCCH H Ethanal common name = acetaldehyde common name = formaldehyde
CH3CH2CH2CHO 4 Carbons so base name is butane Drop -e and add al butanal CHO ending indicates aldehyde