Organic Chem hw

Use intermolecular forces to explain why alkanes with 1-4 Care gases; 5-16 Care liquids; and greater than 16 C are solids.

Alkanes are nonpolar molecules; their intermolecular forces are induced dipole-induced dipole (ID-ID) attractions. Molecules with large sizes have greater ID-ID attractions. The sizes of alkanes with 1-4C are rather small, so they have little or no attractions among one another; therefore, they are gases at room temperature. However, as molecular sizes increase, the ID-ID attractions also increase. That is why alkanes with 5-16C are liquids and greater than 16C are solids at room temperature.

What is the functional group for Ketone?

C(C=O)C

Name and draw the condensed structural formulas of all butanols (including isomers).

CH3CH2CH2CH2OH: 1-butanol, (CH3)2CHCH2OH:2-methyl-1-propanol, CH3CH(OH)CH2CH3: 2-butanol, (CH3)2C(OH)CH3: 2-methyl-2-propanol

What is the condensed structural formula, IUPAC and Common name with 4C for Alcohol?

CH3CH2CH2CH2OH; Butanol; butyl alcohol

What is the condensed structural formula, IUPAC and Common name with 4C for Aldehyde?

CH3CH2CH2CHO; butanal; Butyraldehyde

What is the condensed structural formula, IUPAC and Common name with 4C for Amide?

CH3CH2CH2CONH2; Butanamide; Butyramide

What is the condensed structural formula, IUPAC and Common name with 4C for Ketone?

CH3CH2COCH2O; 2-butanone; methyl ethyl ketone

What is the condensed structural formula, IUPAC and Common name with 4C for Ester?

CH3CH2COOCH3; Methyl propanoate; propyl formate

What is the condensed structural formula, IUPAC and Common name with 4C for Ether?

CH3CH2OCH2CH3; ethyl ether; Ethoxyethane

What is the condensed structural formula, IUPAC and Common name with 4C for Carboxylic acid?

CH3CH3CHCOOH; 2-methylpropanoic acid; Isobutyric acid

What is the functional group for Aldehyde?

CHO

Write the molecular structure for 1-heptyne

CH≡CCH2CH2CH2CH2CH3

What is the functional group for Ether?

COC

What is the functional group for Amide?

CONH2

What is the functional group for Ester?

COOC

What is the functional group for Carboxylic acid?

COOH

Give an example of a Cis- Cyclic

Cis-1,2- dimethyl cyclohexane

Give an example of a cis C=C double bond

Cis-1,2-dichloroethene

What is the general formula for Cycloalkane

CnH2n

What is the general formula for alkene.

CnH2n

What is the general formula for alkyl.

CnH2n+1

What is the general formula for alkanes.

CnH2n+2

What is the general formula for alkyne

CnH2n-2

Give two reasons why octanol is not soluble in water?

Each octanol molecule has eight carbon atoms, which makes octanol almost non-polar. And the large octyl (C8H17-) group makes it difficult for water forming hydrogen bonds with hydroxyl group in octanol due to steric hindrance. That is why octanol is not soluble in water.

What kind intermolecular force operates in hydrocarbons? High or low boiling point results from this type of intermolecular force? Why?

Induce dipole-induced dipole forces operate in hydrocarbons. Low boiling points are expected from this type of weak intermolecular force.

Use intermolecular forces to explain Why ethanol is soluble in water in any proportion?

Intermolecular attraction forces (H-bonding) within ethanol and water molecules are comparable, therefore, ethanol is soluble in water in any proportion.

Are hydrocarbons soluble in water? Give a brief explanation why of why not. The answer must involve hydrogen bonding.

No, hydrocarbons being non-polar are not soluble in water, because hydrocarbons can't form hydrogen bonds with water.

What are positional isomers?

Positional isomers: structural isomers which differ only in the position occupied by a substituent, which is the -OH group in the example below.

What is the general condensed structural formula for Aldehyde?

RCHO

What is the general condensed structural formula for Amide?

RCONH2

What is the general condensed structural formula for Carboxylic acid?

RCOOH

What is the general condensed structural formula for Ester?

RCOOR'

What is the general condensed structural formula for Ketone?

RCOR'

Give a buffer system that is prepared with an amine and its conjugated acid. Indicate the base and its conjugate acid in your answer.

RNH2(base)/RNH3+ (conjugate acid)

What is the general condensed structural formula for Alcohol?

ROH

What is the general condensed structural formula for Ether?

ROR'

Rank the following compounds by solubility in water, from most soluble to least. Explain, the answer must involve hydrogen bonding. 1) CH3CH2OH 2) CH3OCH3 3) CH3CH2NH2

Ranking : 1)>3)>2) All three compounds can form hydrogen bonds with water, so they are all soluble in water. Since more polar hydroxyl (-OH) group can form stronger hydrogen bonds with water than its less polar counterpart amino (-NH2) group, so CH3CH2OH should have greater solubility than CH3CH2NH2 in water. Ether like CH3OCH3 is only slightly polar, and its hydrogen bonding with water is not very strong compare to both CH3CH2OH and CH3CH2NH2, therefore, it is ranked the least soluble in water. In fact, both CH3CH2OH and CH3CH2NH2 are miscible in water.

What is an isomer of CH3CH2CH2OH

(CH3)2CHOH

For which compound is hydrogen bonding not possible? Explain your selection. (i) CH3COOCH3 (ii) CH3COOH (iii) CH3CONHCH3 (iv) CH3CH2CH2OH

(i) CH3COOCH3 The hydrogen atom in methyl group of CH3COOCH3 is not polar enough to form hydrogen bonding due to insufficient electronegativity difference between C and H atoms.

Amines are compounds that would be classified as (i) neutral salts (ii) strong base (iii) weak bases (iv) strong acids (v) weak acids Explain your selection

(iii) weak bases A pair of non-bonded electrons on N atom in amines are capable of accepting an H+ ion, so amines are bases. Amines like NH3, only partially ionize in water making them weak bases.

Which is an isomer of CH3CH2NH2 ? (i) CH3CH2OH (ii) CH3CH2CH2NH2 (iii) CH3NH2 (iv) CH3NHCH3

(iv) CH3NHCH3

What is the functional group for Alcohol?

-OH

Ethyl methyl ether and propanol, which compound has a higher boiling? Use intermolecular forces to explain your answer.

The propanol has a higher boiling point than that of ethyl methyl ether, because ethyl methyl ether molecules cannot form hydrogen bonds among themselves like in propanol molecules. The inability of forming hydrogen bonds in ethers is responsible for their lower boiling point in comparison to alcohol with same molar mass.

What causes the formation of geometric isomers (cis-trans isomer)?

The restriction of C-C bond rotation causes the formation of Cis-trans isomers. This happens in molecules containing a double bond or cyclic structures.

Give an example of a trans C=C double bond

Trans 1,2-dichloroethene

Give an example of a Trans- Cyclic

Trans-1,2- dimethyl cyclohexane

Dimethylether and ethanol soluble in water? Explain your answer. The answer must involve hydrogen bonding.

Yes, they are both soluble in water. Because both dimethylether and ethanol can form hydrogen bonds with water molecules.

An aromatic hydrocarbon has a ______ ring. A benzene ring is a 6-membered ring of carbon atoms with alternating ______ and _____ bonds.

benzene; C-C; C=C

In amides, a ______ group is attached to an alkyl or aryl group and an _______group.

carbonyl; amino or amine

Which one of the following ethers has the highest boiling point? Use intermolecular force to explain your selection. Explain. a) CH3OCH3 b) CH3CH2OCH2CH3 c) CH3CH2CH2 OCH2 CH2CH3 d) CH3CH2CH2CH2 OCH2 CH2CH2CH3

d) CH3CH2CH2CH2 OCH2 CH2CH2CH3 has the highest boiling point. This is because all above four ether molecules have weak dipole-dipole attractions from C-O-C linkage. The remaining factor which determines the boiling point is the strength of induced dipole-induced dipole attraction from alkyl groups. Since CH3CH2CH2CH2 OCH2 CH2CH2CH3 molecules have the largest alkyl group among the four ethers here, therefore, they have the highest ID-ID attraction, which gives the highest boiling point.