Lecture 3_Chem250_Phenix_2025

2.2.2.5 – Hydrates, Hemiacetals, and Acetals

• Hemiacetals:

  • Functional groups with a carbon connected to two oxygens:

    • One oxygen is connected to another carbon.

    • The other oxygen is connected to a hydrogen.

• Acetals:

  • Functional groups with a carbon connected to two oxygens:

    • Both oxygens are connected to other carbons.

  • Acetals are not usually subdivided.

2.2.2.7 – Primary, Secondary, and Tertiary Amines

• Amines:

  • Functional groups where a nitrogen is connected to carbons and/or hydrogens.

  • Subdivided based on the number of carbons attached to the nitrogen:

    • Primary Amines: One carbon attached to nitrogen.

    • Secondary Amines: Two carbons attached to nitrogen.

    • Tertiary Amines: Three carbons attached to nitrogen.

2.2.2.8 – Nitro and Nitriles

• Nitros:

  • Functional groups where nitrogen is double bonded to an oxygen and is connected to another oxygen.

  • Atoms have formal charges but overall, nitros are neutral and the octet rule is satisfied for N and O.

• Nitriles:

  • Functional groups where nitrogen is triple bonded to a carbon.

2.2.2.9 – Imines

• Imines:

  • Functional groups where nitrogen is double bonded to a carbon.

  • Similar to aldehydes and ketones but with nitrogen in place of oxygen.

  • The nitrogen will have another group attached to it.

2.2.2.10 – Halides

• Halides:

  • Functional groups where a halogen is connected to a carbon.

  • Subdivided based on the specific halogen.

2.2.2.11 – Thio-Equivalents

• Thio-Groups:

  • If there is a sulfur instead of an oxygen, indicate it with a thio-[group].

  • Technically, these have formal names but often referred to as thio-groups.

2.2.2.13 – The Carbonyl Group

• Carbonyl Group:

  • Characterized by a carbon double bonded to oxygen.

  • Very common in organic compounds and fundamental to many functional groups.

  • Carbonyls themselves are not functional groups but confer similar reactivities to the functional groups they are part of.

2.2.3 – Summary

• There are many functional groups to memorize, but many are similar.

• Importance of Practice: Identifying functional groups in complex molecules can be tricky; highlight and practice identifying them.

2.3 – Intermolecular Forces

• Intermolecular Forces:

  • Molecules can attract each other through noncovalent interactions (no sharing of electrons, only electrostatic attraction).

  • These forces affect properties like boiling points, melting points, and solubility.

  • Functional groups influence the type of intermolecular forces possible.

2.3.1 – Electrostatic Interactions

• These arise from charged atoms (similar to ionic bonds).

• A cation (positive) attracts an anion (negative).

• Strongest intermolecular forces, particularly in non-aqueous solvents.

2.3.2 – Dipole-Dipole Interactions

• Results from polar bonds with permanent (partial) charges, where:

  • A partial positive charge (δ+) attracts a partial negative charge (δ-).

  • Typically the second strongest intermolecular forces.

2.3.2.1 – Hydrogen Bonding

• A specific strong type of dipole-dipole interaction.

• Occurs when a hydrogen atom bonded to electronegative heteroatom interacts with another electronegative atom.

• Critical for physical properties like solubility, melting, and boiling points.

2.3.3 – Dispersion

• Arises from temporary instantaneous charges in atoms/molecules.

• Temporary dipoles influence other molecules to also become dipoles, resulting in weak attractions.

2.4.1 – Boiling and Melting Point Effects

• Intermolecular forces impact the energy required to change state (melting/boiling).

• Stronger intermolecular forces correspond to higher boiling/melting points.

2.4.2 – Solubility Effects

• Intermolecular forces influence the solubility of substances in solvents.

• "Like dissolves like" principle: Similar intermolecular forces between solute and solvent enhance solubility.

2.5.1 – Basics of Nomenclature

• A systematic name includes a prefix (substituents), root name (longest carbon chain), and suffix (principal functional group).

2.5.2 – Simple Alkanes and Root Names

• Alkanes are the simplest functional group. The root name is based on the longest carbon chain with a suffix of "ane."

2.5.3 – Branched Alkanes

• Alkane substituents are named with root name + "yl." Number to minimize substituent numbers.

2.5.4 – Greek Numerical Prefixes

• Number carbons, add numerical descriptor, then substituent name for clarity.

2.5.6 – Cyclic Alkanes

• Add “cyclo” to the root name. Number substituents appropriately, ensuring the larger alkyl group gets the lower number.

2.5.7 – Alkenes and Alkynes

• Alkenes have priority over alkanes, altering suffix to "ene." Alkynes also take precedence and their suffix is "yne."

2.5.8.1 – Priority and Functional Group Prefixes and Suffixes

• IUPAC functional groups are ranked by priority. The highest priority group contributes the suffix to the name.

2.5.9 – How to Determine the IUPAC Name from the Structure

• Steps to derive names from structures:

  1. Identify highest priority functional group(s).

  2. Number the main carbon chain.

  3. Determine the suffix.

  4. Identify the root name, then prefixes for substituents.

2.5.10 – How to Draw the Structure from the IUPAC Name

• Process involves:

  1. Drawing the carbon skeleton.

  2. Adding highest priority groups based on the suffix.

  3. Adding substituents as per the prefix.

2.5.11 – Abbrev., Limitations of the IUPAC System, and Trivial Names

• IUPAC nomenclature is complex but necessary for clear communication in chemistry. Trivial names are often used for common compounds.