GLOSSARY Absolute configuration(Section 7.5): The three-dimensional Activating substituent (Sections 12.10 and 12.12): A group rrangement of atoms or groups at a stereogenic center. that when present in place of a hydrogen causes a particular Acetal(Section 17.8): Product of the reaction of an aldehyde or reaction to occur faster. Term is most often applied to a ketone with two moles of an alcohol according to the substituents that increase the rate of electrophilic aromatic Active site(Section 27. 20): The region of an enzyme at which the substrate is bound. RCR′+2R"OH→>RCR′+H,O Acylation(Section 12.7 and Chapter 20): Reaction in which an acyl group becomes attached to some structural unit in a molecule. Examples include the Friedel-Erafts acylation and the conversion of amines to amides Acetoacetic ester synthesis(Section 21.6): A synthetic method Acyl chloride(Sections 2.3 and 20.1 ) Compound of the type for the preparation of ketones in which alkylation of the enolate of ethyl acetoacetate RCCI CCHCOCH_CH3 R may be alkyl or aryl. Acyl group(Sections 12.7 and 20. 1): The group the key carbon-earbon bond-forming step Acetyl coenzyme A (Section 26.1): A thiol ester abbreviated as R may be alkyl or aryl. that act source of acetyl groups in biosynthetic Acylium ion ( Section 12.7): The cation R-C Acetylene (S 1. 18 and 9.1): The simplest alkyne, HC≡CH is converted to another Achiral (Section 7. 1): Opposite of chiral. An achiral object is Addition(Section 6.1): Reaction in which a reagent X-Y ble on its mirror image. adds to a multiple bond so that x becomes attached to one Acid(Section 4.6): According to the arrhenius definition,a f the carbons of the multiple bond and Y to the other. substance that ionizes in water to produce protons. Accord 1, 2 Addition (Section 10.10): Addition of reagents of the type ing to the bronsted-towry definition, a substance that do X-Y to conjugated dienes in which X and Y add to adja- nates a proton to some other substance. According to the cent doubly bonded carbons Lewis definition, an electron-pair acceptor. Acid anhydride (Sections 2.3 and 20. 1): Compound of the type R2C=CH-CH=CR2 R2C-CH—CH=CR RCOCR 1. 4 Addition (Section 10.10): Addition of reagents of the type Both r groups are usually the same, although they need not X-Y to conjugated dienes in which X and Y add to the ter Acid dissociation constant Ka (Section 4.6): Equilibrium con- stant for dissociation of an acid R2C=CH—CH=CR2 R2C-CH=CH—CR2 H[A-] THAJ Addition-elimination mechanism (Section 23.6 ): Two-stage In G-1 Forward Main Menu TOC Study Guide Toc Student OLCMHHE WebsiteG-1 GLOSSARY Absolute configuration (Section 7.5): The three-dimensional arrangement of atoms or groups at a stereogenic center. Acetal (Section 17.8): Product of the reaction of an aldehyde or a ketone with two moles of an alcohol according to the equation Acetoacetic ester synthesis (Section 21.6): A synthetic method for the preparation of ketones in which alkylation of the enolate of ethyl acetoacetate is the key carbon—carbon bond-forming step. Acetyl coenzyme A (Section 26.1): A thiol ester abbreviated as that acts as the source of acetyl groups in biosynthetic processes involving acetate. Acetylene (Sections 1.18 and 9.1): The simplest alkyne, HCPCH. Achiral (Section 7.1): Opposite of chiral. An achiral object is superimposable on its mirror image. Acid (Section 4.6): According to the Arrhenius definition, a substance that ionizes in water to produce protons. Accord￾ing to the Brønsted—Lowry definition, a substance that do￾nates a proton to some other substance. According to the Lewis definition, an electron-pair acceptor. Acid anhydride (Sections 2.3 and 20.1): Compound of the type Both R groups are usually the same, although they need not always be. Acid dissociation constant Ka (Section 4.6): Equilibrium con￾stant for dissociation of an acid: Ka [H][A] [HA] RCOCR O X O X CH3CSCoA O X CH3CCH2COCH2CH3 O X O X RCR 2ROH H2O O X RCR W W OR OR H Activating substituent (Sections 12.10 and 12.12): A group that when present in place of a hydrogen causes a particular reaction to occur faster. Term is most often applied to substituents that increase the rate of electrophilic aromatic substitution. Active site (Section 27.20): The region of an enzyme at which the substrate is bound. Acylation (Section 12.7 and Chapter 20): Reaction in which an acyl group becomes attached to some structural unit in a molecule. Examples include the Friedel—Crafts acylation and the conversion of amines to amides. Acyl chloride (Sections 2.3 and 20.1): Compound of the type R may be alkyl or aryl. Acyl group (Sections 12.7 and 20.1): The group R may be alkyl or aryl. Acylium ion (Section 12.7): The cation . Acyl transfer (Section 20.3): A nucleophilic acyl substitution. A reaction in which one type of carboxylic acid derivative is converted to another. Addition (Section 6.1): Reaction in which a reagent X±Y adds to a multiple bond so that X becomes attached to one of the carbons of the multiple bond and Y to the other. 1,2 Addition (Section 10.10): Addition of reagents of the type X±Y to conjugated dienes in which X and Y add to adja￾cent doubly bonded carbons: 1,4 Addition (Section 10.10): Addition of reagents of the type X±Y to conjugated dienes in which X and Y add to the ter￾mini of the diene system: Addition—elimination mechanism (Section 23.6): Two-stage mechanism for nucleophilic aromatic substitution. In the R2CœCH±CHœCR2 R2C±CHœCH±CR2 W X W Y X±Y R2CœCH±CHœCR2 R2C±CH±CHœCR2 W X W Y X±Y R±CPO RC± O X RCCl O X