• Hóa học - Chapter 15: Conjugated systems, orbital symmetry, and ultraviolet spectroscopyHóa học - Chapter 15: Conjugated systems, orbital symmetry, and ultraviolet spectroscopy

    These compounds are an isolated diene, two conjugated dienes, and a conjugated triene. The isolated diene will have the shortest value of lmax (185 nm), close to that of cyclohexene (182 nm). The second compound looks like 3-methylenecyclohexene (232 nm) with an additional alkyl substituent (circled). Its absorption maximum should be around (232 ...

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  • Hóa học - Chapter 17: Reactions of aromatic compoundsHóa học - Chapter 17: Reactions of aromatic compounds

    Benzylic carbocations are resonance-stabilized, easily formed. Benzyl halides undergo SN1 reactions. Benzylic halides are 100 times more reactive than primary halides via SN2. The transition state is stabilized by a ring.

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  • Hóa học - Chapter 18: Ketones and aldehydesHóa học - Chapter 18: Ketones and aldehydes

    Forms hydrazone, then heat with strong base like KOH or potassium tert-butoxide. Use a high-boiling solvent: ethylene glycol, diethylene glycol, or DMSO. A molecule of nitrogen is lost in the last steps of the reaction.

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  • Hóa học - Chapter 19: AminesHóa học - Chapter 19: Amines

    In the presence of a strong base, primary amides react with chlorine or bromine to form shortened amines, with the loss of the carbonyl carbon atom. This reaction, called the Hofmann rearrangement, is used to synthesize primary and aryl amines.

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  • Hóa học - Chapter 20: Carboxylic acidsHóa học - Chapter 20: Carboxylic acids

    Ammonia and amines react with acid chlorides to give amides NaOH, pyridine, or a second equivalent of amine is used to neutralize the HCl produced to prevent protonation of the amine.

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  • Hóa học - Chapter 21 - Part 1: Structure and properties of carboxylic acid derivativesHóa học - Chapter 21 - Part 1: Structure and properties of carboxylic acid derivatives

    The carbonyl carbons of acid derivatives appear at shifts around 170 to 180 ppm, slightly more shielded than the carbonyl carbons of ketones and aldehydes. The a-carbon atoms absorb around 30 to 40 ppm.

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  • Hóa học - Chapter 21 - Part 2: Reactions of carboxylic acid derivativesHóa học - Chapter 21 - Part 2: Reactions of carboxylic acid derivatives

    Polycarbonates are polymers bonded to the carbonate ester linkage. The diol used to make Lexan® is a phenol called bisphenol A, a common intermediate in polyester and polyurethane synthesis.

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  • Hóa học - Chapter 22: Condensations and alpha substitutions of carbonyl compoundsHóa học - Chapter 22: Condensations and alpha substitutions of carbonyl compounds

    When attack occurs at the carbonyl group, protonation of the oxygen leads to a 1,2-addition. When attack occurs at the β-position, the oxygen atom is the fourth atom counting from the nucleophile, and the addition is called a 1,4-addition.

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  • Hóa học - Chapter 23: Carbohydrates and nucleic acidsHóa học - Chapter 23: Carbohydrates and nucleic acids

    Adenosine monophosphate (AMP), a regulatory hormone. Nicotinamide adenine dinucleotide (NAD), a coenzyme. Adenosine triphosphate (ATP), an energy source.

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  • Hóa học - Chapter 24: Amino acids, peptides, and proteinsHóa học - Chapter 24: Amino acids, peptides, and proteins

    Denaturation is defined as the disruption of the normal structure of a protein, such that it loses biological activity. Usually caused by heat or changes in pH. Usually irreversible. A cooked egg cannot be “uncooked”.

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